AD-Ri43 4587 PRELIIMINRRY GUIDELINES FOR MAINTENANCE OFPPOLYURETHRNE i/iFORM (PUF) ROOFING SYSTEMS(U) NAVAL CIVIL ENGINEERINGLAB PORT HUENEME CA R L ALUMBRUGH ET AL. MAR 847UNCLRSSIFIED NCEL-TN-1691 F/G 13/13 NLEmnmmmmlmmlmm

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TITLE: PRELIMINARY GUIDELINES FOR MAINTENANCE OFPOLYURETHANE FOAM (PUF) ROOFING SYSTEMS

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[ I i I AUTHOR: R. L. Alumbaugh, S. R. Conklin, and D. A. Zarate'.-:

-ta_ DATE: March 1984 -

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U DATE: March 198

i- mi- |n' J PROGRAM NO: YO995.01.004.610, '__YF60.5 34.091.01.203 ;,

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NAVL CVILENGINEERING LABORATORYPORT HUENEME, CALIFORNIA 93043 D I

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REPORT DOCUMkENTATION PAGE BEADIN'OPT(tINFR

I REPORT NUMBER 12 GOVT ACCESSION NO R1,ECIPI0

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TN-1691 DN987077 A A~v4 TITLE lend S~b,,,I.1 TYPE OF RIFuGRY & PFR- D ' D FREC)

PRELIMINARY GUIDELINES FOR MAINTENANCE Not Final; Oct 1978 - Apr 1983OF POLYURETHANE FOAM (PUF) ROOFING I EFRIGO- EOTNME

SYSTEMS7 AUTI£OR(s. 0 CONTRACT OR 5RAPTN..,MRER71,

R. L Alumbaugh. S. R. Conklin, and D. A. Zarate

9 PERFORMING ORGANIZATIDN NAME AND ADDRESS 10 PROCREKI ELEMENT PROJEC TASKAREA A WORK UNIT NUMBERS

NAVAL CIVIL ENGINEERING LABORATORY 63725N; Y0995.01.004.610;Port Hueneme, California 93043 YF60.534.091.0l.203

9 1 CONTROLLING OFFICE NAME AND ADDRESS 12 REPORT DATE

Naval Facilities Engineering Command 13MR 1984 -,

Alexandria, Virginia 22332 53Q- -MONITORINO AGENCY NAME a ADDRESSI ,jI e,.n I~n Con,,uflong Off.~-e) IS SECURITY CL ASS S',lI h- rp-)

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I8 SUPPLEMENTARY NOTES

f9 KEY WORDS (ConI-n. Oflf*V t .1d. atnc n., d ,d-nI'y b,, blocrk -ubril

Roofs, sprayed polyurethane foam, maintenance, inspection, insulation

20 ASRAPT (Conl-nui Aid it.~ d 0 ...n.V y rid ,.I,fy by block .. ,.nbe,)

"is report presents details of experiments and preliminary guidelines for main-taining sprayed polyurethane foam (PUF) roofing systems, which have been used inincreasing numbers in recent years by government and the private sector. Many of thesePUF roofs are now requiring maintenance because of improper materials, improperapplication, or length of time in service (age). Standard methods and procedures for

(Continued)

DD 'M' 1473 EDITION OF 1 NOV 155 IS OBSOLETE Unclassif ied ___

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20. Continued

maintaining and repairing PUF roofs have not yet been developed or used by manu-

facturers or contractors to any great extent. In general, each contractor has his ownspecial maintenance procedures. A number of experiments have been conducted byNCEL in an investigation to establish effective procedures for maintenance of PUFroofing systems.

Libr, -Card -

Naval Civil Engineering Laboratory

PRELIMINARY GUIDELINES FOR MAINTENANCE OFPOLYURETlANE FOAM (PUF) ROOFING SYSTEMS(Not Final), by R. L. Alumbaugh, S. R. Conklin, and D. A. ZarateTN-1691 53 pp illus March 1984 Unclassified

1. Inspection 2. Insulation I. Y0995.O.004.610

This report presents details of experiments and preliminary guidelines for maintainingsprayed polyurethane foam (PUF) roofing systems, which have been used in increasingnumbers in recent years by government and the private sector. Many of these PUF roofs arcnow requiring maintenance because of improper materials, improper application, or lengthof time in service (age). Standard methods and procedures for maintaining and repairingPUF roofs have not yet been developed or used by manufacturers or contractors to any greatextent. In generai, each contractor has his own special maintenance procedures. A numberof experiments have been conducted by NCEL in an investigation to establish effective pro-cedures for maintenance of PUF roofing systems.

UnclassifiedSECURITY CLASSIrICATION OF T.IS PAGE'Whe, t).'- F-d)

*TW 7W- .4...7

CONTENTS

Page

INTRODUCTION .. ............... ............ I

BACKGROUND .. ............... ............. 2

SCOPE OF WORK. .. .............. ............ 3

EXPERIMENTAL INVESTIGATIONS .. ........ ............ 4

Phase 1 - Maintenance of Four Failed Test Panelsof PUF Systems Taken From Each of ThreeExperimental Sites (12 Panels Total) .. ........ 5

Phase 2 - Maintenance of 12 Coated and 8 UncoatedPUF Test Panels. ......... .......... 6

Phase 3 - Maintenance of Family Housing Roofs atthe Naval Air Station (NAS) Lemoore,Calif.. .......... ............. 7

Phase 4 - Test and Evaluation of Repair Methods forSmall Areas of PUP Systems at the NavalReserve Center (NRC), Clifton, N.J.,and NCPEL Test Sites .. ................ 8

Phase 5 - Maintenance of Aged PUF System TestPanels Taken From NWC China Lake andMC1IWTC Pickel Meadows, Calif., TestSites. ......... ............... 9

RESULTS AND DISCUSSION .. ............... ...... 10

Phase I. ......... ............... ... 10Phase 2. ........ ................ ... 13Phase 3. ........ ................ ... 14Phase 4. ........ ................ .... sPhase 5. ........ ................ ... 16

FINDINGS AND CONCLUSIONS .. ............... ..... 17

RECOMMENDATIONS .. ........ .................. 17

ACKNOWLEDGMENT. ........ ............... ... 18

REFERENCES. ......... ............... .... 18

APPENDIX -Preliminary Guidelines for Maintenance of r

Polyurethane Foam (PUP) Roofing .. ........... A-1

Availabhility Codes

Avail an~d/or--Dist Special

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INTRODUCTION

Polyurethane foam (PUF) roofing systems have been used more fre-quently over the past decade, not only in the private sector but also atNaval shore bases. However, as with any new material, problems haveoccurred. When these roofing systems were first introduced, mistakeswere made in their specification and application. Frequently, the roofswere installed and forgotten (i.e., there was no inspection and preventivemaintenance program). Both of these factors led to many problems and aconsequent high rate of failure.

PUF degrades when exposed to sunlight and must be protected by asuitable elastomeric coating system. If the elastomeric coating isapplied too thin, is subjected to excessive mechanical damage, or hasweathered excessively, it tends to spall or flake from the substrate,exposing the foam. When this happens, the surface must be recoated assoon as possible. If this is not done, the roofing system deterioratesand eventually fails as a result of ultraviolet (UV) degradation andwater absorption into the degraded foam.

At some point in time, generally 6 to 12 years after application,the elastomeric coating systems will weather (age) to the point wheremaintenance is required to provide continued protection to the foam.When properly applied and protected, PUF should perform its requiredfunction as a roofing system for a minimum of 20 years. With the high-quality elastomeric coating systems that are currently available, itshould be possible to obtain 20 years of service with only one recoating.Even higher quality coating systems are under development, and it isanticipated that some of these may perform well for the entire 20-yearperiod. These life expectancies are predicated on an annual inspectionand preventive maintenance schedule during which minor repairs are made.Without annual preventive maintenance, it is anticipated that the normalPUF elastomeric coating systems will perform for 6 to 10 years. Withannual preventive maintenance, the life expectancy should be 8 to 12 yearsbefore recoating is required.

While there are numerous procedures and materials currently availablefor maintaining built-up roofing (BUR) systems, there are no standardizedprocedures for maintaining PUF roofing systems. The actual proceduresemployed are determined by the knowledge and ingenuity of the individualcontractor. The objective of this research is to (1) investigate existingmaintenance procedures for PUF roofs; (2) develop new maintenance procedures,materials, and methods for PUF roofs; and (3) standardize the bestprocedures for Navy use. This report summarizes the research that wascarried out on maintenance of PUF roofing systems and provides preliminaryguidelines (see Appendix) for properly maintaining these roofing systems.

.' BACKGROUND

Over the past 15 to 20 years, maintenance of roofs and roofingsystems has become an ever-increasing problem. The problem with BURsystems has been compounded by changes in the composition of bitumen andfelts, by material shortages, by poor workmanship, and by other factors

- *-.that lead to poor performance and short service life of these waterproof-ing systems. This problem was emphasized by an Air Force report thatBUR systems designed for a 20-year life are performing an average of12 years (Ref 1). According to the National Bureau of Standards (NBS),about 15% of BUR systems fail within 5 years after construction, andindications are that within the Department of Defense (DOD) the rate offailure is even higher. Part of the shortened service life must beattributed to a lack of proper maintenance procedures and funding forroof maintenance programs. The best information available indicatesthat the annual maintenance cost for roofs at Naval shore activities isover $25 million.

Because of the increasing seriousness of the roof maintenanceproblem, the Naval Civil Engineering Laboratory (NCEL) was tasked by theNaval Facilities Engineering Command (NAVFAC) to investigate roofingsystems under YF54.593.01l.O1.00l, '"Investigation of Roofing Systems forMaintenance of Naval Shore Structures." (The work is currently beingconducted under Y0995-01-004-610, "Roofing Inspection and Maintenance.")This research was to be directed toward all areas of roofing problems.The objective of the investigation was to provide a significant reductionin maintenance costs for roofing systems at Naval shore bases by definingexisting problems and identifying conventional and new materials andmethods that might eliminate or alleviate these problems. An extensivesurvey of Naval shore bases was conducted in different climatic areas todefine and delineate the most recent roofing problems (Ref 2).

The experimental program was to cover a broad spectrum of roofingproblem areas that were either known or would be delineated by theroofing survey. In pursuing this aspect of the program, funds wereprovided to NBS to provide a state-of-the-art report on the effect ofmoisture on BUR (Ref 3). In addition to this contractual effort,support was also provided to the U.S. Bureau of Reclamation (USBR)Research Laboratories to aid in the preparation of a report on anextensive research effort that USBR had conducted earlier on new roofingsystems (Ref 4).

teEarly in the NCEL roofing research program, NAVFAC requested thatteLaboratory cooperate with the Northern Division of NAVFAC (NORTHNAVFAC)

to develop and carry out an experimental field investigation of spray-applied PUF roofing systems at the Naval Reserve Center (NRC), Clifton, N.J.Reports of that investigation are presented in References 5 and 6.Because of the requirement to assist in the development of plans for theexperimental field investigations of PUF roofing systems at NRC Clifton,the original experimental roofing investigations at NCEL were directedtoward: (1) PUF roofing materials, and (2) coatings for protecting thePUF from weathering. This resulted in an interim report describingexperimental weathering and laboratory studies of these relatively newroofing materials (Ref 7).

Since this initial work, much has been learned about these materials,their proper specification, and proper application. The industry hasadvanced, and much needed guidance is available to provide background

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information on materials and procedures necessary to obtain a good,long-lasting foam roofing system. Current guidelines for the design,specification, and installation of PUF roofing systems are available inNCEL publications (Ref 8 and 9) and Urethane Foam Contractors Association(UFCA) publications (Ref 10). These guidelines can be used until NavyFacility Guide Specification NFGS-07545, "Sprayed Polyurethane Foam forRoofing Systems" (pending), is issued. Navy Type Specification TS-07540covers the use of silicone rubber coatings for protecting PUF. Thistype specification is scheduled for revision and updating in the nearfuture and should also include catalyzed urethane coatings. As a resultof NCEL's experience with PUF roofing systems, the initial maintenanceeffort was directed toward these unique materials.

SCOPE OF WORK

A study of roof maintenance procedures used by contractors indicatedthat the most frequently used method of foam repair is to broom thecoated PUF roof, air blow* to remove dirt and deteriorated coating, andrecoat with a suitable coating. This procedure involves the leastamount of effort and is the least expensive. Brooming is frequently a

NA, ~satisfactory maintenance procedure as long as a large percentage of theexisting coating is intact and little, if any, degraded foam is exposed.

i A more radical procedure consists of complete removal and reapplicationof the PUF roofing system. This is only necessary when the existing PUFis so badly degraded that it no longer serves its proper function as aroofing system.

In between these two extremes, there are several other possibleprocedures. Procedures investigated in this study include the following:

1. Broom the existing surface and recoat with a suitable elastomericcoating system. This is a minimum procedure.

2. Broom the existing surface, prime, and recoat with a suitableelastomeric coating system. Priming may be required to provide properbonding of the elastomeric coating or to stabilize a weathered foamsurface.

3. Broom the existing surface, apply a new lift of foam, and coat

with a suitable elastomeric coating system (as with a new foam roof).

4. Broom the existing surface, prime, apply a new lift of foam,and coat with a suitable coating system. Priming may be required toobtain a good bond between the foam and the existing roof surface.

5. Shave or sand the existing surface to remove bad coating and

e.. foam (until only good-quality foam remains). Blow off or vacuum alldust, and coat with a suitable elastomeric coating system or prime and

%e *Whenever the foamed roof surface is broomed, any loose residual dirt

is blown off with compressed air that is free of oil and water.

3

coat with a suitable coating system. Priming may be required to obtainproper bonding of coating to foam or to stabilize the sanded foamsurface.

6. Shave or sand the existing surface to remove bad coating andfoam (until only good-quality foam remains). Blow off or vacuum alldust, apply a new lift of foam, and coat with a suitable elastomericcoating system, or prime, apply a new lift of foam, and coat with asuitable elastomeric coating system. Priming may be required to providea better bond between the new foam and the sanded foam surface or toencapsulate any remaining dust.

All of these procedures were investigated to disclose their limita-tions and to determine which are most effective under different prevailingroof conditions. It is expected that the choice of maintenance methodfor any given roof will be dictated by the condition on that particularroof at the time. At times, two or more methods might be required on aroof to obtain the most effective results.

In addition to the maintenance procedures mentioned above, localizedroof repairs may be required. For instance, small areas up to 10 ft2 ofpoor-quality or water-saturated foam may need replacement. This type ofrepair is easily accomplished by removing the bad foam and replacing itwith new foam applied either by a foam spray unit or by using single- ortwo-package "canned" foam units.

Annual preventive maintenance procedures should extend the effectivelife of PUF roofs. Techniques and materials for performing this annualmaintenance are included in this investigation. Finally, some of theelastomeric coatings used on foam may present special problems when theyrequire recoating; this aspect was investigated.

EXPERIMENTAL INVESTIGATIONS

Research directed toward development or selection of optimum main-tenance methods for PUF roofing systems was conducted both in thelaboratory and in the field. To provide weathered PUF roof test panelson which to perform experiments, 1-1/2 inches of Witco SS-0125A/SS-0126Bfoam (3-pcf density) was spray-applied to eight 4- by 8-foot sheets of1/2-inch plywood. The foam was coated with one of the following materials:

" TT-P-95, Type 1, a rigid chlorinated rubber coating normallyused for exterior concrete and masonry (three panels)

" TT-P-19, an acrylic latex coating normally used for exteriorwood or masonry (two panels)

" TT-P-29, a latex coating for interior surfaces (three panels)

These particular coatings were selected because they had been usedunsuccessfully on PUF roofs at several Naval activities before it wasrecognized that elastomeric coatings are required to accommodate the

4

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large expansions and contractions experienced by PUF roofs. The rigidcoatings applied over PUF roofs at field activities had failed from6 months to 2 years after application. The eight panels coated with thethree systems listed above were placed on outdoor exposure racks atNCEL's experimental weathering site at the Naval Weapons Center (NWC),China Lake, C,.lif.*

471 Unfortunately, these coating systems performed better on the4- by 8-foot test panels than on roofs at the other locations. After

19 months of field exposure, only three of the eight panels (TT-P-95coated) had deteriorated sufficiently to be included in the maintenanceresearch study at that time. The other five panels were transferred tothe NCEL marine weathering site at Port Hueneme, Calif. Since theresearch could not be delayed until the 4- by 8-foot panels were ready,another approach was taken and the work was divided into five phases asshown below.

Phase 1 - Maintenance of Four Failed Test Panels of PUF Syste..s TakenFrom Each of Three Experimental Sites (12 Panels Total)

In order to proceed with the initial investigation as soon aspossible, it was decided to utilize PUF roofing system panels that wereincluded in another portion of the NCEL roof research program. Four ofthe systems described in Reference 2 and exposed at each of the threeNCEL experimental weathering sites had either failed or were nearingfailure after varying periods of exposure. These 12 systems and theirconditions are listed in Table 1 and shown in Figures la, lb, 1c, andId. A study of these figures shows that the condition of the systemsvaried considerably, due both to the different generic types and to theparticular exposure site at which the systems were exposed. However,all 12 systems were considered to be in need of maintenance and wereused in the investigation. The variation in the sample condition aidedthe study in permitting the use of several of the procedures listedunder the SCOPE OF WORK section.

As with many other systems, proper surface preparation is the most* important consideration in the maintenance of PUF roofing systems. If a

deteriorated PUF roof surface is improperly prepared, it is highlyunlikely that any maintenance procedure will be effective. As noted inthe SCOPE OF WORK section, many different procedures for cleaning thePUF coating or otherwise preparing the PUF roof surface are included inthe investigation in order to determine their relative effectiveness.These procedures involve tools or equipment for brooming, shaving, andsanding a degraded PUF roof surface. The different types of broomingequipment included in the overall investigation are shown in Figure 2.All of these except the long-bristled, heavy-duty push broom were used

*NCEL has experimental weathering sites at the following locations:

(1) NCEL (marine weather); (2) NWC, China Lake, Calif. (desert site);and (3) Marine Corps Mountain Warfare Training Center (MCMWTC), PickelMeadows, Calif. (cold weather site).

5

in the Phase 1 brooming operations. The equipment investigated for

sanding and shaving is shown in Figures 3a and 3b. The sander is aheavy-duty, electrical disk sander, while the shaver is a 24-inch foamplane manufactured by Gusmer Corporation for shaving foam applied betweenstuds in a wall. A similar piece of equipment, Quick Plane 2116, manufac-tured by Grand Rapids Scarfer Company, has recently been received andwill be tested in the near future. The only other known equipmentmarketed specifically for shaving or preparing deteriorated PUF roofingsurfaces is also marketed by the Grand Rapids Scarfer Company. Thisheavy-duty piece of equipment may be too heavy for use on many conven-tional roof decks.

The procedures and materials used for maintaining the 12 deterio-rated systems and their new system numbers are given in Table 2. Thereconditioned PUF roofing systems were coated or recoated with a two-component (catalyzed) urethane elastomer applied in two coats. Br' theblack base coat and the oyster white topcoat were applied at the _e of1-1/2 gal/l00 ft2 to give an estimated total dry film thickness30 mils.

The experimentally maintained PUF panels of Phase I have beexposed at the Port Hueneme site for about 5 years. Photomacrog P' ofthe maintained surfaces were taken initially and periodically assystems weathered until the samples mentioned below were cut. Only onepanel of each of the systems was prepared and exposed initially. Becauseof this, samples were not cut from these specimens for adhesion testinguntil they had been exposed for about 2 years, and approximately on anannual basis thereafter. The performance of each of the treatments wasalso rated, generally on an annual basis. After 4 years of weathering,additional small samples were cut from samples 7F-I and 8F-1. Duringthe maintenance procedure both were sanded to good-quality bare foam,

a", 8F-1 was primed, and both were then refoamed. These samples were takento determine if use of a primer improved the bonding character of thenew foam to the old foam.

Phase 2 - Maintenance of 12 Coated and 8 Uncoated PUF Test Panels

Each of the three 4- by 8-foot foamed panels coated with TT-P-95were cut into four equal sizes of 2 by 4 feet. The TT-P-95 showedmudcracking, crazing, flaking, and line cracking. In addition, foam hadbeen spray-applied to eight 2- by 4-foot plywood panels that had beenallowed to weather uncoated until the foam surfaces had degraded. Theseeight uncoated panels were used in surface preparation studies involvingsanding. In all, 20 test panels were used.

All six of the experimental maintenance procedures were included inthis phase of the investigation. The procedures, equipment, and materialsemployed in this phase are listed in Table 3 for each of the maintainedPUF systems. The coating system used with this group of panels wasDiathon, an acrylic latex elastomer applied in two coats at 1-1/2 gal/100 ft2/coat (30 mils wet film thickness per coat). The degraded surfaces(TT-P-95) of syst ms 9F-1,2 and 1OF-1,2 were thoroughly broomed with arattan push broom (Federal Specification H-B-71). The surfaces (TT-P-95)of systems 11F-1,2 through 14F-1,2 were brushed with the two hand brushes(such as a GI brush) shown in Figure 2 to determine the relative cleaning

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effectiveness of brooming and brushing. The degraded uncoiLed foamsurfaces of systems 15F-1,2 through 18F-1,2 were sanded with a heavy-dutydisk sander to remove all degraded material, exposing a good-qualitysanded foam surface. Following the surface conditioning, all loose foammaterial and dust were removed by blowing the surface with an air hose.Duplicate panels of each of the maintenance systems were prepared for

4 Phase 2, and all panels have been exposed at the Port Hlueneme site forabout 4 years. A small section of each of the duplicate panels wasremoved periodically and returned to the laboratory to determine perfor-mance characteristics. Physical properties, such as coating and foamadhesion over unprimed and primed surfaces, were determined annually.These characteristics are described in Reference 7. In addition,photomacrographs were taken initially and at 6- to 12-month intervals asthe systems weathered, and the systems were inspected and rated annually.

Phase 3 -Maintenance of Family Housing Roofs at the Naval Air Station(NAS), Lemoore, Calif.

j4NAS Lemoore, Calif., had foamed the roofs of about 108 of their

family housing units in the late 1960s. These were flat-roofed unitsthat had built-up roof (BUR) systems that were leaking. Since the roofdecks were nearly level, the gravel was removed from the BUR and a

.1 course of lightweight concrete was added to provide slope. The roofsft

were then foamed with 3/4 to 1 inch of 2-lb/ft density foam and coated.The housing unit roofs were foamed in two different groups, with adifferent coating system used in each group. One of these coatings was

an aluminum asphalt; records were not available to determine the generictype of the second coating system. In any event, it did not appear tobe elastomeric.

Considering that these roofs were 7 to 8 years old when inspectedby NCEL personnel in 1977, the coated foam was in relatively good condition

* overall. The coating had spalled from the foam in a number of smallareas on each housing unit roof, permitting the foam to degrade. However,degradation was limited to the surface of the foam and had not progressedto any appreciable depth into the foam. Scraping the degraded foam witha knife blade uncovered good-quality foam a short distance beneath thesurface. In addition, a number of small blisters approximately 4 to6 inches in diameter were evident between lifts on many of the roofs.The blistezs were probably caused by perspiration dropping from the foamapplicators on one lift of foam as the next lift was being applied.

Station personnel did not want to remove the old foam because thisoperation might affect the integrity of the lightweight concrete. As aresult it was recommended that degraded coating and foam be removed byshaving or sanding, the exposed foam surface primed, and 1-1/2 inches ofnew foam applied and protected with an acceptable elastomeric coatingsystem with granules. The contract specifications were prepared accordingto this recommnendation.

The roofs were refurbished in the fall of 1977 in accordance withthe contract specifications mentioned above. The degraded foam andcoating on most of the roofs were removed with a heavy-duty disk sander(see Figure 4). The blisters mentioned above were removed in a similarmanner. With the remainder of the roofs, the sanding disks tended to

7

clog when removing the coating. As a result, it was necessary to use aBUJR spudding machine to remove the coating and a small amount of thefoam. Since this left a very rough surface, the remaining foam wassanded lightly to give a surface similar to that obtained when diisksanding only was used.

After the sanding was completed, all loose foam and dust were blownfrom the roof with an air hose, and the existing foam was given a tiecoatof hydrocarbon primer used principally to assure good bonding betweenold and new foam. Following the priming, an additional 1-1/2 inches ofnew foam (3-lb/ft3 density) was applied (Figure 5). Then a catalyzedurethane was applied in three coats, with each coat applied at the rateof I gal/100 ft2. Mineral roofing granules were broadcast into the wettopcoat at the rate of 50 lb/100 ft2 . The dry film thickness of thecoating was approximately 30 mils. An overview of a finished roof isshown in Figure 6.

*As the work at NAS Lemoore progressed, an attempt was made to*incorporate several of the six NCEL maintenance procedures into the

program. Procedure No. 6 (i.e., sand, prime, foam, and coat) was beingused on most of the housing units by the contractor. However, by the

*time the contractor had agreed to try some of the other procedures,there were only two roofs left to complete. As a result, only procedureNo. 6 was included. In general, the work progressed well, resulting insatisfactorily maintained roofing systems.

Phs 4-Test and Evaluation of Repair Methods for Small Areas of P1W

Sysemsatthe Naval Reserve Center (NRC), Clifton, N.J., and NCEL

Tes Site

The first three phases of the investigation described above weredirected toward maintenance of the entire deteriorating PUF roofingsystem. Many times only small areas of a foam roof (i.e., 1 to 10 ft2 )require maintenance. These usually occur when there is some deficiencyin the quality of the foam caused by: (1) the two components of thefoam being off ratio when dispensed, (2) the foam sustaining mechanicaldamage following application, or (3) the foam becoming wet. In suchcases, it is generally necessary to remove the affected foam down to theroof deck, refoam, and coat the newly foamed patch. When P1W sprayequipment is available, patching of small areas presents few problems.However, if proper equipment and trained personnel are not available,other procedures must be used. This phase of the investigation wasdirected toward the small patch repair.

As noted above, with foam spray equipment and experienced personnel,patching repairs are simple and easy. Such repairs are described in

Reference 5, where approximately 15 to 20 ft2 of spongy foam was removedfrom the test roofs at NRC Clifton, N.J., replaced with new foam, and

* coated. This provided a monolithic roofing system that would performthe same as a new roofing system.

The patching investigation on the test roofs at Clifton, N.J., wasinitiated for two reasons. First, as noted in Reference 5, birds hadremoved from 1-1/2 to 2 ft2 of foam from beneath the coating near thegravel stops. Second, it was necessary to remove samples of I ft2 offoam from each of the five PUF roofing systems at the Clifton site todetermine the insulating characteristics of the foam after weatheringfor 5 years.

4'8

When PUF spray equipment is not available, other sources of PUF,such as canned foam or foam boardstock, must be used. Canned foam isavailable in two forms: (1) sing)--component (one can), where the foamreacts with atmospheric moisture to cure; and (2) two-component (twocans), in which the components react to cure. The single-component foammust cure about 24 hours before it can be sanded. The two-componentfoam is sufficiently well cured in 1 to 2 hours to enable it to besanded.

There are a number of single-component foams available in conven-tional spray can containers. Two of these were included in thisinvestigation: (1) UFC Handi-Foam, manufactured by United FoamCorporation, Compton, Calif.; and (2) Polycel One, manufactured byCoplanar Corporation, Oakland, Calif. There are only two two-componentfoam materials known to NCEL. These are Froth-Pak, manufactured byInsta-Foam Products, Inc., Joliette, Ill.; and Versifoam, manufacturedby Universal Foam Systems, Cudahy, Wis. The Froth-Paks were included inthe investigation. The two-component foam is available in three differentcontainer sizes, the smallest of which is the conventional paint spraycan (approximately 12 fluid ounces). The two cans each have a plastictube that is connected into a plastic nozzle. When the trigger on theFroth-Pak is activated, the two liquid components meet and are mixed asthey pass through and are dispensed from a special plastic mixing nozzle.Both the single- and two-component foams extrude from the cans as afroth (like shaving cream). The foams then expand about 50% as theycure. Plastic nozzles are available for spraying as well as for frothing.

Both single- and two-component canned foams were investigated atthe NRC Clifton test site. Additional tests were conducted at NCEL inareas where PUF samples were removed for thermal conductivity measurements.The NCEL tests involved the two-component canned foam and either PUF orstyrofoam insulation board that was cut to the approximate size of thefoam removed from the roof. The shaped boardstock was then set intofour or five beads of caulking material that had been applied to theroof deck, the area between the boardstock and the adjacent foam wascaulked, and the surface of the foam was protected with a proper caulkingmaterial or coating. The use of both canned foam and foam insulationboardstock for patching is shown in Figure 7.

Phase 5 - Maintenance of Aged PUF System Test Panels Taken From NWCChina Lake and MCMWTC Pickel Meadows, Calif., Test Sites

Concern has been expressed in the industry that the silicone coatingsare difficult to recoat when it is necessary to maintain this type ofcoated PUF roofing system (i.e., the new silicone coating does notadhere well to the old silicone coating). To determine the validity ofthis concern, two 2- by 4-foot experimental panels that had been coatedwith a single-component moisture-cured silicone were returned to NCELfor an additional maintenance operation. One of these panels had beenexposed at the NCEL experimental weathering site at NWC China Lake,Calif., while the second had been exposed at another NCEL site at MCMWTCPickel Meadows, Calif. These two systems had been exposed for 8 yearsat these two sites and were in excellent condition. The only deterio-ration noted was very light checking of the silicone (1/8 to 1/4 inch in-

9

o4.

* - . 174

length) that occurred in the bottom of the valleys of the surface textureof the coating. This checking had occurred when the coating was firstapplied and had not progressed or changed in nature on weathering. Thechecking did not penetrate through the coating into the foam.

The two panels were each divided in half, and four different surfacetreatments were tried, one on each half of the panel, prior to recoatingthe surface with new silicone coating. These surface treatments included:

Panel 1.

System 19F-1 - The surface of the existing weathered siliconewas thoroughly broomed (as might be done with power brooming) to removeall adhered dirt from the silicone.

System 19F-2 - The surface of the weathered silicone wasthoroughly broomed while washing with water to remove all adhered dirt.The surface was then washed with clean water and allowed to dry completely.

Panel 2.

System 20F-l - The surface of the weathered silicone waswashed with a pressure water spray (approximately 170 psi) to removeadhered dirt and allowed to dry completely.

System 20F-2 - The surface of the weathered silicone waswashed and scrubbed with water and trisodiun phosphate (TSP) detergent,washed with clean water, and allowed to dry completely.

The cleaning operations all gave good clean surfaces. However, thepanel that was washed with TSP appeared to be the cleanest. The cleaned,dry surfaces were then topcoated with two coats of moisture-cured siliconeapplied by spray at the rate of 1 gal/10O ft2/coat. Small samples werecut from these panels to determine the adhesion of the new coating tothe old coating before the systems were exposed and after 6 months ofweathering at the Port Hueneme experimental weathering site.

RESULTS AND DISCUSSION

Interim results on these maintenance studies after a little over2 years of weathering on the PUF maintenance panels were presented inReference 11. Reference 11 also presented interim procedures for main-taining foam that could be used pending additional investigation. Thiscurrent report presents results of a 5-year laboratory and small-scalefield study along with preliminary guidelines for maintaining foam roofs

4 (see the Appendix). These preliminary guidelines will become recommendedcriteria following their use in full-scale field maintenance operations.Each phase of the investigation is described below.

Phase 1

As noted earlier in the report, the condition of the 12 weathered

* 4,systems used in this phase varied. For all practical purposes, no two

10

systems were in the same condition. Because of this, it was notpossible to have duplicates as in Phase 2; only qualitative informationwas obtained from this series for the first 28 months. Thereafter,small samples were cut from each of the panels for the adhesion testsmentioned earlier. Results of the inspection of these systems forperformance during the 5 years of weathering are given in Table 4.

The three methods used in this phase for preparation of thesurfaces were brooming, sanding, and shaving. All 12 panels were firstbroomed to determine the effectiveness of this technique. This treat-ment was relatively effective only on system IF-1. It was also the onlytreatment used on systems 1F-2 and 2F-1. This was done because theauthors have seen P1W roofs with this degree of deterioration merelybroomed and coated, and wanted to determine if this was a satisfactorytreatment. Figures 8 and 9 show system 1F-2 after brooming and coating,respectively. As noted in Table 4, brooming is not an effective treatmentfor surfaces that have a moderate percentage of flaked coating.

System lF-l did not have as much of the original urethane coatingspalled from the foam as systems 1F-2 and 2F-1. As a result, systemIF-i was performing better than the other two and was rated as good;system IF-2 (see Figure 10a and b) was rated as failed and system 2F-1was rated poor, respectively, after 5 years of exposure. System IF-2had absorbed water after 1 year of exposure. The slightly better per-formnance of system 2F-1 (see Figure 10c) over system IF-2 (Figure 10b)is attributed in part to the use of a primer, which improves the adhesionof the new coating to the old coating (compare adhesive properties forsystems 2F-1 and IF-2 in Table 5).

Where the old coating was mostly intact, as with system IF-i,brooming was found to be an effective surface preparation. On theremaining nine panels of Phase 1, brooming was found to be ineffectivebecause deterioration of the coating and foam surfaces was too advanced.

* Attempts were made to use the foam plane on these panels, but it did nothave sufficient cutting ability to remove these coatings, particularlythe moisture-cured urethanes. Even though some of these coatings werebadly deteriorated, the remaining portion was still quite rubbery andtough. Only the disk sander was able to remove deteriorated P1W roofingsystems; it was also used to partially sand the most deteriorated portionsof systems 3F-1, 3F-2, 3F-3, 4F-1, and 4F-2. While the disk sander dida relatively good job, it is not effective in removing deterioratedrubberlike coatings, such as moisture-cured urethanes. A new, morerugged foam planer that may be more effective has recently been receivedand will be evaluated in the near future. This unit has a much heavierblade than the one that was tested.

After 5 years of weathering, systems 3F-i and 3F-2 were providinggood to very good protection to the P1W panels. Less than 10% of theold weathered coating had spalled before this maintenance was performed.Where there were breaks in the original coating (i.e., where deterioratedcoating had been sanded to quality foam), the new coating effectivelybridged over the transition from foam to old coating. After 5 years ofweathering, some cracking of the maintenance coating was evident. Thisminor cracking was more prevalent on system 3F-1 than on system 3F-2.The third system in this group, system 3F-3, had failed after 5 years ofweathering. There were many interface areas of old coating to foam; themaintenance coating was unable to bridge this transition and is crackingaround these areas.

System 4F-1 is providing good protection to the PUF after S yearsof exposure. The old weathered coating on this panel had no more than10% spalled areas, which had been sanded to remove degraded coating andfoam. This caused some cracking of the maintenance coating where it hadoriginally bridged these transition areas between sanded foam and oldcoating. System 4F-2, on the other hand, had more than 40% spalling ofthe original weathered coating, and about this percentage of the panel

* had been sanded lightly to good-quality foam. There were relatively fewbreaks in the maintenance coating where it had been applied over areasof transition from sanded foam to good-quality coating. System 4F-2 wasrated very good after 5 years of exposure.

A comparison of the adhesive characteristics of systems 3F and 4F(Table 5) does not show a clear-cut advantage for either using or notusing a primer. The reason for this is believed to be the variabilityof the substrate that was maintained. In some cases, the primer wasapplied to the sanded foam, while in other cases it was applied toweathered coating (i.e., variable test results may be caused by theprimer being applied over different substrates). It is emphasized thatthere was no loss of adhesion of new coating to old weathered coatingwith any of the systems mentioned above. The new coating was wellbonded to the old coating in every case.

Systems 5F-1 through 8F-l required complete removal of old deterio-rated coating and foam using the disk sanders. As mentioned above, theresidual urethane elastomeric coatings (systems SF-i and 6F-1) are very

4 tough and abrasion resistant, and their removal with a disk sander isnot only time consuming but also tends to gum up the disk sanders,requiring frequent changing of the disk. The weathered butyl-hypalonsystems (systems 7F-1 and 8F-1) were not quite as difficult to removebecause they have less abrasion resistance than the urethane elastomers.Use of the heavy-duty foam scarfer may produce better results in suchsituations.

Systems SF-i and 6F-1 both performed in an excellent manner, provid-ing complete protection to the sanded foam substrate for up to 5 years(see Table 4). The catalyzed urethane elastomer bonded very well to thesanded foam surface except for a few blisters between the sanded foamsurface and the new coating. Use of the primer in system 6F-1 appearedto have minimized the blistering, which is probably caused by isolatedlarger cell structure at the sanded foam surface. The urethane primer

provided a definite improvement in adhesion of the coating to the sandedfoam surface, which may be increasing with continued exposure (seeTable 5). Application of a coating to a sanded or scarfed foam surface,whether primed or not, is generally not recommended. However, theseresults suggest that such a procedure would be acceptable in small,isolated areas. When small areas are sanded to provide a smoothersurface, the sanded areas should be primed, and at least one additionalbase coat beyond that specified for the total roof should be applied inthe sanded/primed area.

Systems 7F-1 and 8F-l have also performed in an excellent mannerfor the 5 years of exposure. These two systems, sanded foam surfacethat was refoamed and the new foam coated, were similar except for theprimer applied to the sanded foam of system 8F-1. Because of the newfoam catalyzed urethane coating system, these two systems would be

V~;

12

I- V

"* expected to perform well. They were included to determine if priming ofthe sanded foam surface is advantageous prior to refoaming. Data inTable 6 for these two systems show that the adhesive character of thenew foam to old foam is enhanced by use of the primer.

Phase 2

The objective of this phase of the work was to obtain quantitativedata relative to the effectiveness of two levels of brooming and sanding,as well as to determine whether or not it is advantageous to prime priorto coating or foaming over old weathered coatings or over sanded foamsurfaces (see Table 3).

Two levels of brooming were investigated. The first, systems 9F-1and 9F-2 and 1OF-I and 10F-2, utilized a rattan push broom, which did avery effective job at cleaning dirt, chalk, loose coating, and deterio-rated foam from the panels. The second treatment, designated as brushing,was utilized on the remainder of the weathered TT-P-95 panels, includingpanels IIF-I and IIF-2 through 14F-I and 14F-2. It was found thatbrushing was not nearly as effective for removing products of PUF roofingsystem deterioration as the rattan push broom.

The weathered uncoated foam panels were very easily and efficientlycleaned of degraded foam using the disk sander (systems 15F-1 and 15F-2through 18F-1 and 18F-2). Figures Ila through lld show the sanded,primed, and coated panel of system 16F-2. Figure 12 shows system 16F-1after 4 years of exposure. This system is performing well at this time.

The second panel of each series (i.e., 9F-2, lOF-2, etc.) wasreturned to NCEL on a periodic basis, a small section cut off for adhesiontesting, the exposed surfaces coated, and the panel returned to the testrack. The series has been exposed for a period of about 4 years. Thecoating on those systems whose surfaces were prepared for recoating bybrooming or brushing (i.e., systems 9F-1 to 12F-2) showed a very slighttendency to crack where the new coating bridged over cracks in theoriginal coating or over small spots where the original coating hadflaked from the foam. However, this was not serious, and all of thesystems in this series were providing excellent protection to the coatedfoam substrate. One factor observed was that when an elastomeric coatingis applied over a sanded foam surface, the coating is more easily com-pressed into the foam than when the coating is applied over a foamsurface with a skin (i.e., the skin tends to make the foam surface morerigid). Thus, a coating applied over a sanded foam surface may be moreeasily damaged. It is for this reason that sanding of the foam followedby an extra heavy coating should be used only in small, isolated areas.

The effect of using a butyl primer on the adhesion of new coatingto a weathered coating surface or to a sanded foam surface is given inTable 5. The data show lower adhesive values for the primed surfacesthan for the unprimed surfaces, which is a reverse of that found whenusing the urethane primer in Phase 1. While the differences between theadhesive values for primed and unprimed surfaces were substantial after1 year of exposure, these appear to be reduced with additional exposure.This suggests that the problem may involve solvents of the butyl primerand solvent retention during the initial exposure period. The retainedsolvent may tend to migrate out of the system with additional time ofexposure, thereby narrowing the difference in the adhesive value betweenprimed and unprimed surfaces.

13

i

77,-7 -77 -7 -17-7. W7~- -. --7-

Application of the butyl primer over a brushed, weathered coatingand over a sanded foam surface prior to refoaming increased the adhesivecharacteristics of the new foam to those surfaces (Table 6). The reasonfor this is not clear since, as noted above (Table 5), the butyl primerdid not enhance the adhesive character of the acrylic elastomer coatingto the different surfaces. However, because of the lower incidence ofblistering when a coating is applied over a sanded foam surface, thebetter adhesive character of new foam to old when using the butyl primer,and the overall enhanced adhesion characteristics with the urethaneprimer, use of a primer appears desirable.

Phase 3

The 108 PUF roofing systems on the family housing units at NASLemoore, Calif., that were refurbished in the fall of 1977 have been inplace for almost 6 years. About two-thirds of these roofs are perform-ing well and currently require little or no maintenance. Four to six ofthe units have had moderate to extensive maintenance conducted recently(i.e., blistered or delaminated foam, or foam that was wet or a poorquality, was removed and the areas were refoamed and coated). Theremaining one-third of the 108 units have isolated examples of blistering,foam delamination, cracking of the coating, or spongy foam (off-ratiofoam). These areas should receive proper and prompt maintenance as soonas possible to prevent accelerated deterioration and failure of theaffected roofs. Maintenance procedures should include (1) cutting outand removing any blistered, delaminated, poor-quality or wet foam;(2) beveling the edges of cut-out areas; (3) allowing the area to dry ifwet; and (4) refoaming and coating new foam. Cracked or flaked coatingareas should be sealed with an appropriate caulking material. If theexisting coating is severely aged, these units should be recoated.

The actual reason for the problems in the PUF roofs showing earlydeterioration has not been determined. However, it is believed to becaused by the attempt to save as much of the original PUF roof as possible.The original PUF had been applied over lightweight concrete, which wasused to provide slope over a flat BUR. Blistering or delamination ofthe foam can be attributed to several factors: (1) moisture in theoriginal foam or in the lightweight concrete, (2) original foam too thinafter sanding, (3) poor bond between the original foam and the lightweightconcrete, or (4) questionable integrity of the lightweight concrete. Inall probability, the principal problem lies with number (3) or (4). Ifthe original foam is not well bonded to the lightweight concrete or ifthe lightweight concrete does not have good integrity, stresses that

develop in the new foam as it ages could cause the foam to disbond fromthe substrate, causing blistering or delamination problems.

The results to date on this refurbishing suggest that this is avery satisfactory maintenance procedure. However, the problems thathave been observed indicate the requirement for a very rigorous inspectionof the original foam roofs once they have been scarfed or sanded to beassured that the existing foam is dry and well bonded to a sound, drysubstrate. It would probably be prudent in such a case to have moisturesurveys of the roofs to establish that they are in fact dry. Consideringthe good performance of the majority of these roofs, the alternative and

14

U 3.*.**?~

T. 6-. . . . . . F.

considerable additional expense of a complete tear-off of the originalfoam, the lightweight concrete fill, and the BUJR membrane, the procedureused is considered a very viable alternative.

Phase 4

This phase of the investigation deals with maintenance of smallareas of a PUFh roof rather than the total roofing system. It is firmlybelieved that this small maintenance activity should be carried out inconjunction with annual inspections. During such inspections, verysmall defects can be corrected with caulking material carried by theinspector. During the annual inspections at the NRC Clifton test site(Ref 6), it was a relatively simple matter to remove degraded coating/foam areas from small spots on the roof and repair them on the spot witheither silicone or acrylic caulking material. Such a procedure oftenprevents small problems from becoming large roof defects.

If a defect I ft2 or larger is found during the annual inspectionor noted at other times, it then becomes necessary to use the mainte-nance procedures for small areas. As described in the EXPERIMENTALINVESTIGATIONS section, single- and two-component "canned" foams andprecut foam insulation boardstock were investigated.

The single-component "Handi-Foam" did not perform in an acceptablemanner. Although this froth foam filled the voids relatively well, thecell structure of the foam was very irregular, resulting in extremelypoor physical characteristics and causing the applied coating to spallwithin 1 year. The poor-quality patches and foam required removal andreplacement the following year. NCEL experience with Polycel I has beenmore favorable in that it provides a better quality foam material with amore uniform cell structure. It must be emphasized that the single-component materials require a curing time of about 24 hours before theycan be shaped or coated. Where station forces are performing the mainte-nance, such a delay may not be a problem.

The two-component canned foams also expanded and filled the voidswell but, like the single-component foams, produced a very rough surfacethat had to be shaped. This froth foam will not only cure within I to2 hours, but it also provides a better quality foam with better cellstructure than that obtained with the single-package materials. Becauseof the short curing time, the two-component foams can be shaped with adisc sander within 2 hours after application. As an alternative tosanding, a relatively flat surface can be obtained by placing a piece ofplywood wrapped in polyethylene over the foamed patch as it is applied.A weight can be placed on top of the plywood to hold it in place, andthe foam then rises against and conforms to the flat surface of theweighted plywood. After the proper curing time (i.e., 24 hours forsingle-component foam or about 2 hours for two-component foam), theplywood can be removed and the foam patch coated with the proper coatingor caulking material.

If the canned foam is not available, PIJF or styrofoam boardstockinsulation appears to be an acceptable alternative. This is adhered tothe roof deck with caulking material, shaped (if required), and thenwaterproofed or protected from the environment with either a suitablecoating or caulking material. This procedure has worked relatively wellfor over 2 years in tests conducted at NCEL.

15

Of the three methods mentioned, NCEL believes that the two-component canned foams provide a better patch than either the single-component canned foam or the foam boardstock. Among other factors, thetwo-component canned foams provide a monolithic roofing system consistingof essentially the same foam material as the original roof, althoughthese foams are generally of slightly lower density (i.e., less than2 lb/ft3). The single-component foams are somewhat different chemically,and the boardstock introduces a cold joint around the perimeter of thepatch.

* Shaping of the foam does give a sanded or cut foam surface withoutthe normal foam skin. As noted earlier, a sanded foam surface is normallynot recommnended except for small, isolated areas, since the coating overa sanded surface is more easily damaged than a coating over a skinnedsurface. It was observed in tests at NRC Clifton that when only twocoats of silicone coating were applied over the shaped surfaces, thecoating would start to deteriorate in a couple of years, while the

caulking material, which is similar but thicker, has held up very wellfor up to 5 years. When coating is used over a sanded foam surface, itshould be applied in multiple coats to provide a minimum dry film thick-ness of 35 to 40 mils. The coating would have to be applied over atleast a 2-day period, which could cause logistic problems. As a result,

'~ ~ NCEL favors the use of caulking materials for the patching operation,which permits protecting the foam in one operation.

New, small, foam spray machines are currently available for smallN foam roof repairs. These machines, which have small canisters of the

two foam components on the unit. and require only a 110-volt power sourceand low-pressure, low-volume compressed air (I cfm), provide the bestmaintenance procedure because the two-component foam used is the samequality as in the original roof. Where a base has a number of foamroofs, such as on family housing, the procurement and use of this typeof equipment could be Mgst beneficial and cost effective. The ModelFF-111 Little Big Shot ,available from Gusmer Corp., is one type offoam spray machine.

Phase 5

Results of the research to determine the adhesion of new siliconecoatings over weathered silicone coatings are presented in Table 7. Thesingle-component silicones were applied over weathered silicones thathad received one of four different surface treatments: (1) broomed,

(2) washed with water, (3) washed with moderate pressure water blasting(i.e., 100+ psi), and (4) washed with detergent. A study of the adhesiondata in Table 7 suggests that brooming would normally be an adequatesurface preparation, although there is not much difference in the adhesivevalues between the coatings applied over the four different surface

1. treatments. However, in certain heavy industrial atmospheres, oilysubstances may be deposited on the roof, and washing with detergent maybe required to properly prepare the surface. There appears to be atrend in which the adhesive values increase in each of the four cases.The adhesive values, in fact, show a tendency to increase to the valuesdetermined previously for the adhesion of this silicone coating to foam(i.e., 9 to 10 kg/cm2 (Ref 7)). In this latter case, failure of thesystem always occurred cohesively in the foam. In the current study

16

(Table 7), failure was normally an adhesive failure between the new and

old coating. This is not serious because the adhesion of the new to oldcoating appears to increase with time. While there have been some

*problems in the past with the adhesion of the single-component, moisture-cured silicone to foam, a new base coat of this material has recentlybeen introduced that has incorporated an adhesion promoter. The newbase coat is expected to enhance the adhesive character of this systemand is being investigated.

FINDINGS AND CONCLUSIONS

1. A PUF roofing system can be easily maintained using methods andmaterials described in this report.

2. A strong inspection and maintenance program can extend the time forrecoating as much as an additional 5 years.

3. When removing small areas of poor-quality, wet, or degraded foam,the areas should be refoamed with conventional foaming equipment. Ifthis equipment is not available, repairs can be made using two-componentcanned foam or foam boardstock. Any voids between new and old foamshould be caulked and the new foam surface protected with appropriatecaulking material or 35 to 40 mils of elastomeric coating.

4. If spalling of weathered elastomeric coating is distributed uniform-ly over the roof and is less than 10%, the roof can generally be satis-factorily recoated. In such cases, a tiecoat of primer recommended by

the coating manufacturer should be applied before recoating. While useof the primer may or may not enhance the adhesion of the new coating tothe weathered coating, depending on the primer employed, it does appearto improve the overall performance of the coating.

5. New sprayed PUF applied over an existing primer-coated foam systemhas performed very well in these studies. While such a procedure is notapplicable in all cases, it can be used. Each application should beconsidered on a case-by-case basis.

RECOMMENDATIONS

1. A strong annual inspection and maintenance program should be institutedto prolong the life expectancy of foam roofs and extend the time betweenrecoating cycles.

2. The preliminary procedures specified in this report should be testedin full-scale field trials to determine their effectiveness.

3. Coating a sanded foam surface is generally not recommended. However,coating small, isolated areas (approximately 5 to 10 ft2 appears topresent no problem as long as the area is not a high traffic area andthe coating thickness is at least 35 to 40 mils.

17

-J...............................,........... . ............. ..-.. . -.. . . ........ .. ..

4-, V- V% .7. 77 7 - -K

L:b

4.

A 4. When refoaming over an existing coated foam roof, the roofing system

should be thoroughly inspected for roof defects to ensure that it is dry(by means of a nuclear survey or other specialized inspection technique);any wet or degraded areas should be removed, allowed to dry, and refoamed;and the weathered surfaces should be cleaned and primed prior to refoaming.Additional foam should not be applied over an impermeable coating orover a silicone-coated foam roof.

ACKNOWLEDGMENT

The authors wish to express their appreciation to Materials Engineer-ing Technicians Valente Hernandez and John Crahan and Physical ScienceTechnician Nathalie Milliken for preparing the test panels, conductingthe tests, and reducing the data for this report.

. REFERENCES

1. E. Wyatt and H. Torriello. "Good quality in roof construction,"Engineering and Services Quarterly, Aug 1977.

-%

2. J.R. Keeton and R.L. Alumbaugh. Roofing survey of Navy shore bases,%, Civil Engineering Laboratory, Technical Memorandum M-52-77-3. Port14 Hueneme, Calif., Mar 1977.

3. H.W. Bushing, R.G. Mathey, W.J. Rossiter, Jr., and W.C. Cullen..' Effects of moisture in built-up roofing - A state-of-the-art literature

survey, National Bureau of Standards, Technical Note 965. Washington,D.C., Jul 1978.

4. B.V. Jones. Laboratory and field investigations of new materials* * for roof construction (progress report), United States Bureau of

Reclamation, Technical Report REC-ERC-76-4. Denver, Colo., Apr 1976.

5. J.R. Keeton, R.L. Alumbaugh, and E.F. Humm. Experimental polyure-thane foam roofing systems, Civil Engineering Laboratory, Technical NoteN-1450. Port Hueneme, Calif., Aug 1976.

6. R.L. Alumbaugh, J.R. Keeton, and E.F. Humm. Experimental polyurethanefoam roofing systems - II, Naval Civil Engineering Laboratory, TechnicalNote N-1656. Port Huenemc, Calif., Jan 1983.

7. R.L. Alumbaugh and J.R. Keeton. Investigation of spray-appliedpolyurethane foam roofing systems - I, Civil Engineering Laboratory,Technical Note N-1496. Port Hueneme, Calif., Jul 1977.

8. K.H. Coultrap. Principles of urethane foam roof application, CivilEngineering Laboratory, Purchase Order Report PO 79-MR-461. Tempe,

-Ariz., Coultrap Consulting Services, Inc., Jun 1980.

18

9. Sprayed polyurethane foam roofing system, Naval Civil EngineeringLaboratory, Techdata Sheet TDS 82-17. Port Hueneme, Calif., Oct 1982.

10. Specification data and buyers guide for fluid applied roof systems,Urethane Foam Contractors Association. Dayton, Ohio, Jan 1981.

11. R.L. Alumbaugh and J.R. Keeton. Interim procedures for maintenanceof polyurethane foam (PUF) roofing systems, Civil Engineering Laboratory,Technical Memorandum M-52-79-04. Port Hueneme, Calif., Sep 1979.

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20

.

Table 2. Description of Maintenance Procedures - Phase 1

4,-.. .. .... .

System Description Original System

Number of Procedure Primer [ New loamt ,,, R-n- k'Number Description

IF-I Broom and coat 3-1 2.0-lb/ftj

foam; None None (~a, Ibutyl-hypalon coating

IF-2 14-9 2.5-lb/ft3

foam; None None Gao U-66moisture-cured urethane

2F-I Broom, prime, and 14-6 2.5-lb/ft3

foam; Plas Chem None Gaio 11-bcoat moisture-cured urethane 9002-IFR

SBoa surethane

3F-1 Broom, sand some 0-1 2.0-lb/ft3 foam; None None Gaco U-66 O7 ,

portions, and catalyzed urethane sarldtcoat

3F-2 10-3 2.0-Ib/ft' foam; None None Gaco [-66 '10 ,f ,catalyzed urethane sanded

. 3F-2 14-3 20-lb/ft3

foam; None None Gaco 11-66 140% of fa lcatalyzed urethane sanded

4F-I Broom, sand some 10-4 2.0-lb/ft foam; Plas Chem None Gaco U-66 <30 of panelportions, prime, catalyzed urethane 9002-IFR sandedand coat urethane

4F-2 14-8 2.5-lb/ft3

foam; Plas Chem None Gaco U-66 <10% of ainelmoisture-cured urethane 9002-IFR sanded

urethane

-'5 5F-I Sand entire panel 14-1 2.0-lb/ft3

foam; None None Gaco 11-66and coat moisture-cured urethane

* 6F-1 Sand entire 14-4 2.0-lb/ft3

foam; Plas Chem None Gaco li-66panel, prime, and moisture-cured urethane 9002-IFRcoat urethane

7F-I Sand entire 3-3 2.0-lb/ft3

foam; None Witco Gaco U-66panel, foam, and butyl-hypalon coating SS-0125A(coat SS-0126B

(3.0 lb/ft')

8F-I Sand entire 3-4 2.0-lb/ft3

foam; Plas Chem Witco Gaco U-66panel, prime, butyl-hypalon coating 9002-IFR SS-0125A/

_% ,% foam, and coat urethane SS-0126BJ (3.0 Ib/ft'

)

a Gaco U-66 is a catalyzed urethane elastomer system produced by Gaco-Western, Seattle, Wash.b Plas-Chem 9002-IFR is a catalyzed urethane primer produced by Plas-Chem, St. Louis, Mo.

cwitco SS-0125A/SS-0126B foam is a product of Witco Chemical, New Castle, Del.

21

- 5i*-

aTable 3. Description of Maintenance Procedures Phase 2

System Description Original System Primer New FoamNumber of Procedure Description

9F-1 Broom and coat TT-P-95 coating over None Noneand Witco SS-0125A/SS-9F-2 012 6 Bb foam (3.0

lb/ft3)

N 1OF-1 Broom, prime, and TT-P-95 coating over United Noneand coat Witc. SS-O125A/SS- 838 butyl1OF-2 0126B foam (3.0

lb/ft3 )

IlF-1 Brush and coat TT-P-95 coating over None Noneand Witco SS-0125A/SS-1F-2 0126B foam (3.0

ft/lb 3)

12F-1 Brush, prime, and TT-P-95 coating over United Noneand coat Witco SS-0125A/SS- 838 butyl12F-2 0126B foam (3.0

lb/ft3)

13F-I Brush, foam, and TT-P-95 coating over None Witco.. and coat Witco SS-0125A/SS- SS-0125A/

13F-2 0126B foam (3.0 SS-01268lb/ft 3) (3.0 lb/ft3)

14F-1 Brush, prime, TT-P-95 coating over United Witcoand foam, and coat, Witco SS-0125A/SS- 838 butyl SS-0125A/14F-2 0126B foam (3.0 SS-0126B

lb/ft3) (3.0 lb/ft

3)

15F-I Sand and coat Weathered, uncoated None Noneand foam - Witco SS-15F-2 0125A/SS-0126B (3.0

lb/ft3 )

16F-I Sand, prime, and Weathered, uncoated United Noneand coat foam - Witco SS- 838 butyl

16F-2 0125A/SS-0126B (3.0lb/ft

3 )

17F-I Sand, foam, and Weathered, uncoated None Witco

and coat foam - Witco SS- SS-0125A/17F-2 0125A/SS-0126B (3.0 SS-0126B

4, lb/ft3 ) (3.0 lb/ft 3)

18F-1 Sand, prime, Weathered, uncoated United Witcoand foam, and coat foam - Witco SS- 838 butyl SS-0125A/18F-2 0125A/SS-0126B (3.0 SS-0126B

lb/ft3 ) (3.0 Ib/ft 3 )

aThe new coating system for this phase consisted of two coats of Diathon at 1-1/2 gal/sq/coat.Diathon is a product of United Coatings, Spokane, Wash.bwitco foam is a product of Witco Chemical, New Castle, Del.

%5. CUnited 838 butyl primer is a product of United Coatings, Spokane, Wash.

2

IZ?

Table 4. Performance Ratings for Polyurethane Foam (PUF) Maintenance Systems

S New Foam Performance Ratings on We-ithiring

Number Maintenance Procedure Py,;::(lb/ft 4.', _o Ir 2 rr

Phase I

IF-I Broom panel and coat none none VG-G VG-G VG-G VG-G G

1F-2 none none G P-F F F F F2F-1 Broom panel, prime, and none none E VG G G U P

coat3F-I Broom panel, sand some none none E-VG VG VG-G VG-G VG-G VG-G

portions, and coat3F-2 none none VG VG VG VG VG VG3F-3 none none VG VG-G G G P F4F-1 Broom panel, sand some urethane none VC VG VG VG VG-G G

portions, prime, andcoat

4F-2 urethane none VG VG VG VG VG VG5F-I Broom, sand entire panel, none none E E E E 1 E K

and coat6F-I Broom, sand entire panel, urethane none E E E E E F

prime, and coat7F-I Broom, sand entire panel, none 3 E E E E F F

foam, and coat8F-I Broom, sand entire panel, urethane 3 E E E E, E E

prime, foam, and coat

Phase II

9F-I Broom panel and coat none none E E F F,OF- Broom panel, prime, and butyl none E F F

coatI lF-l Brush panel and coat none none E F F F F12F-I Brush panel, prime, and butyl none E E F E F

Coat13F-I Brush panel, foam, and none 3 E E E E E -

coat14F-I Brush panel, prime, foam, butyl 3 E E E E F

and coat1SF-I Sand entire panel and none none E E F E E

coat' 16F-1 Sand entire panel, prime, butyl none E E E E F

and coat17F-I Sand entire panel, foam, none 3 E E E I F F

and coat19F-I Sand entire panel, prime, butyl 3 E E E E F

foam, and coat

aperformance ratings were assigned as follows:

E = Excellent. The system is performing without any noticeable deterioration.VG = Very Good. Only very minor deterioration of the system.G = Good. Although the maintained PUF systems show deterioration, it is not serious.P = Poor. System deterioration is serious. Remedial action will be required in the

'_p near future.F = Failed. Deterioration of the system has advanced to the point of requiring immediate

maintenance.

23_~. .... -.4., , .--., .. . .. ,. . . . . .

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w) -4" I C1 0 00tcc c -'4 00 . . (4.4 4-4 t4-4 LO-4 CC $-4

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24J

Table 6. Adhesion of New Foam to Old Foam-With and Without Primer

Adhesive Properties forExposure Times of--

System Weathered Foam Primer 2.5 Years 4 YearsNumber Treatment Type ____ _______

Stress Moea Stress Mode a_ _ _ _ _ _ _ (psi) Moe (psi) _

Phase I

7F-1 Broomed, sanded, none 22- 2* and foamed

8F-1 Broomed, sanded, urethane 26- 2primed, andfoamed

Phase II

13F-2 Brushed and foamed none 22.6 1 36114F-2 Brushed, primed, butyl 26.7 2/3/4/5 44 2/4

and foamed17F-2 Sanded and foamed none 18.3 1 38 2/118F-2 Sanded, primed, and butyl 34.2 5 42 4/2

foamed

aPiipa mode of failure.

1. Adhesive failure of new foam to old foam.2. Adhesive/cohesive failure with old foam.3. Adhesive failure of primer to old foam.4. Adhesive failure of new foam to primer.5. Adhesive/cohesive failure within new foam.6. Bond of old foam to primed plywood.

25

Table 7. Adhesion of New Silicone Coating toWeathered Silicone (Phase 5) a

Adhesive Properties forExposure Times of--

System Originalmb Surface Treatment Initially 6 Months Coating

Number System

Stress c Stress c(kg/cm

2 ) (kg/cm2) Mode

19F-1 Thoroughly broomed to 5.5 2 8.9 2/1 Dow Corning 3-5000remove adhered dirt exposed at China

Lake, Calif., for

8 years. Systemin excellent con-dition.

19F-2 Thoroughly broomed, 6.2 1/2 7.4 2/1 Dow Corning 3-5000washed with water, and exposed at Chinadried completely Lake, Calif., for

8 years. Systemin excellent con-dition.

20F-1 Washed with a pressur- 7 2/1 8.6 2 Dow Corning 3-5000ized water (- 100 psi) exposed at Pickelspray and dried Meadows, Calif.,completely for 8 years.

System inexcellent con-dition.

20F-2 Washed and scrubbed 6 2/1 7 2/1 Dow Corning 3-5000with trisodium phos- exposed at Pickelphate detergent, Meadows, Calif.,rinsed with clean for 8 years.water, and dried System in

completely excellent con-dition.

a The recoat system consists of two coats of Dow Corning 3-5000 applied at I gal/100 ft2 /coat.

Systems 19F-l and 19F-2 and 20F-1 and 20F-2, respectively, were each applied to one-half ofthe panel.

c Predominant modes of failure in tension were:

1. Adhesive failure of probe to new coating.2. Adhesive failure of new coating to old coating.

26

faN;S"

(a) Butyl-hypalon coating (systems 3-4, 3-3, and 3-2).

x 41W

54ii 0iOle

() Aluminum-filled, hydrocarbon-modified, catalyzed urethane coating(systems 10-1 10-3 and 10 4

Figure 1. Condition of weathered panels included in Phase 1.

7

N-.................. S -. *..--* \ .

'N. 46

(c) Moisture-cured urethane coating (systems 14-1, 14-3, and 14-4).

rf .S

414

(d) Moisture-cured urethane coating (systems 14-6, 14-8, and 14-9).

Figure 1. Continued

28

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29

S

.rr r.-,.;crr -C-''-

(a) Removal of deteriorated foam/coating with a disk sander.

. L ft. -.

(b) Removal of deteriorated foam with a Gusmer Foam Plane.

Figure 3. Mechanical removal of deteriorated coating/foam.

V3

aa , .. _A

Figure 4. Removal of degraded foam/coating with a heavy-duty disk

2sander (NAS Lemoore).

Figure S. Applying an additional 1-1/2 inches of spraiyed1 loam to saildO(1

and primed foam stirface.

Figure 6. Overview of refurbished polyurethane foam roof with urethanecoating and mineral roofing granules (NAS Lemoore).

AI

I .

40

(a) Old foam is cut out.

Figure 7. Patching polyurethane foam (PUT) roofs with canned foam orboa rdstock.

. .:.. . . . . . . . . - - .

'4C

(b) Edge of cut is beveled and all debris is removed.

(c) PUT roof is patched with canned foam.

Figure 7. Continued

- ~

4.

N

- 'V

S

4.4 _

4.. -,

p

L~ ~

(d) New foam patch is shaped with a knife.4.

~6,4.

I'

4. ~

* .r *

4-

444

'44.

'S

4.*4S4.

0~.4%.

cc'.-4,

4.

Figure 7 Continued4-...4%

tt -. 4 . . . . S * 4 5 - * *--------4. - * - -'

S..-

(f) Sanded foam is protected with coating or caulkingand. where required, roofing granules.

(g) Patch using boa rds tuck is ad;he red toe

U roof deck with cail king mate(rid i.

Figure 7. Cont i nued

(h) Perimeter of patch is caulked.

()Foam patch is protected with caulking materifil.

Figure 7 . Corit i fluJCd

7r777 717 .-.

L&

I-

(b Phtoacog p (-4 in.f2).

Fiur 8. ,'v We tee. oitr*trdue&Jeco~dfampe-a-ebrom n -s se .IF-t2)# .

0:1

44'~~-'.4'

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C444~

2-

1'.1 -4. 4-'-

' '

(a) Full panel view.

IPb

S.1 4

A 4

II.

Ix

C, (b) Photomacrograph (-4 inti

Figure 9. Panel IF-2 after maintaining with a catalyzed ,reth:ur

1~4 coating..P,4

4,.-

4%-. 4'

01 18

4 - - 4 4 - . - - 4 4 -4.....4 4 .'-...% . .4.4, % 9.b -. -.

- r.

(a) System IF-2 after weathering for 1 year. Note water and spongyfoam when pressed.

Ilk,

(b) System 1F-2 overview after weathering for 5 years. System hiadfailed.

% Figure 10. Comparison of systems 1F-2 and 2F-1.

TI

'30

(c) System 2F-l overview. This system with primer is performing betterthan system IF-2 without primer.

Figure 10. Continued

(a) Full panel after sanding.

Figure 11. Weathered uncoated control maintained by sanding, priming,

and coating with Diathon (system 16F-2).

140(

...................................................

. 7. F -

(b) Full panel after priming.

(c) Full panel after coating with Diathon.

Figure 11. Continued

41

(d) Photomacrograph of coated panel (--4 in. 2).

Figure 11. Continued

4S42

Appendix

PRELIMINARY GUIDELINES FOR MAINTENANCE OFPOLYURETHANE FOAM (PUF) ROOFING

2 The following guidelines (in NAVFAC specification style) arepresented for maintaining PUF roofs requiring repair. This guidance isbased on research on a limited number of deteriorated 2- by 4-foot PLJFroofing samples reported herein and optimum procedures observed in thefield and are, thus, of a preliminary nature. The procedures designatedbelow will become established guidelines after they have been tested infull-scale field operations and found to be effective under thoseconditions.

1.0 Annual Preventive Maintenance

In order to obtain maximum performance from a PUF roofing system, acontinuous preventive maintenance program with annual inspection andrepair should be established. The annual repair should be carried outin conjunction with the annual inspection. This should consist of athorough visual inspection of the entire PUF roofing system for overallperformance and for both large and small defects in the system. A good,

A strong, preventive maintenance program should extend the life expectancyof the foam's protective coating system an additional 2 to 6 yearsbefore recoating is necessary.

1.1 Repair of Small Defects

Small defects in the coating or foam should be maintained duringthe annual inspection. This should include isolated instances of breaksin the coating attributed to cracking, flaking, or spalling, or rupturedblisters exposing the underlying foam. Minor defects can normally berepaired by cleaning all deteriorated material, dust, and dirt from thedefective area and sealing with a silicone, urethane, or an acryliccaulking material dispensed from a caulking gun. The caulking materialshould be applied carefully so it extends beyond the defect onto thesurrounding existing coating. Repair of small defects prevents themfrom becoming major problem areas.

1.2 Repair of Slightly Larger Areas

S. Inspection of a PUF roofing system will occasionally detect small,isolated areas of poor-quality foam, foam that has been mechanicallydamaged, or foam that is wet. Such areas that are about 1 ft2 or largershould have the affected foam cut out and removed, and the area (includingthe coating) surrounding the cutout should be cleaned, allowed to dry,primed if necessary (see paragraph 2.2), and the foam replaced either

A-1

~~A4~~ "If.. .. .

with two-component canned foam or PUF or other insulation board. Whenthe two-component canned foams are used, the edges of the foam surround-ing the removed area should be beveled, cleaned, allowed to dry, andthen refoamed. The void should be filled about one-half to five-eighthsfull of froth foam directly from the canned foam containers. Once the

'4.. canned foam has been applied, it can be molded (paragraph 1.2.1) orsanded (paragraph 1.2.2) to conform to the approximate shape of thesurrounding foam. The insulation board can also be sanded to conform tothe surrounding foam. The repaired foam should be protected with 35 to40 mils of the appropriate coating material or a thick coat of silicone,urethane, or acrylic caulking compound spread with a putty knife orbrush. This coating or caulk should extend at least 1 inch onto theexisting coating surrounding the patched area.

1.2.1 Molded Froth Foam Surface. A polyethylene-wrapped piece ofplywood is placed over the void and weighted immediately after the frothfoam has been introduced, and the foam is allowed to expand against andconform to the flat surface of the plywood. The foam should cure from 1to 3 hours before coating.

1.2.2 Sanded Froth Foam Surface. The foam is allowed to riseunobstructed, and the surface is then shaped by slicing off high areaswith a flat cutter and sanding flush with a power disk sander. All

~. ~ loose material should be removed from the surface before applying thecaulking compound. The foam should cure from I to 3 hours before sanding

V and coating are attempted.

1.2.3 Insulation Board. If the roof deck is smooth rather thanirregular, as with some metal decks, a patch can be made using PUF orother insulation board of the same approximate thickness as the PUFroofing system. The insulation board should be cut to the approximate

'4 size of the void in the sprayed PUF, several. beads of caulk should beplaced on the roof deck and around the edges of the void, and the insu-lation should be pressed into the caulking material. If the insulationboard is thicker than the sprayed foam roof, the board surface can besanded flush using a disk sander. The surface of the insulation boardshould then be sealed with a thick coat of caulking compound as specified

'4 I in paragraph 1.2.

2.0 Longer Term Preventive Maintenance

~ .4~All of the elastomeric coating systems used to protect PUF from theweather must be recoated periodically to obtain maximum performance froma PUF roofing system. Thus, the overall condition of the elastomericcoating system must be determined during the annual inspection. In the

-~ absence of an annual inspection and a recoating program within theproper time frame, generally 6 to 12 years, the foam roofing system mayfail prematurely.

If the existing coating is weathered and shows signs of deteriorationbut is mostly intact and well bonded (i.e., less than 10% of the coatinghas spalled), the coated foam can usually be cleaned and recoated with a

A-2

suitable elastomeric coating system. Any flaking or spalling of thecoating is usually localized in a few areas rather than spread uniformlyaround the roof.

2.1 Cleaning

The roof surface should be thoroughly cleaned, preferably with apower broom or manually with a rattan or similar stiff-bristled pushbroom. The brooming should be sufficiently vigorous to remove all

*; chalk, dirt, deteriorated coating, degraded foam, or other contamina-tion. Following the brooming, all loose materials should be removedfrom the roof surface by vacuuming or blowing off with dry compressedair.

2.1.1 Washing. Washing of a weathered coating on a foam roofshould be avoided if at all possible because of the possibility of waterabsorption by exposed foam. However, the silicones and certain acrylicelastomers exhibit a tackiness that tends to retain dirt and othercontaminants, requiring removal by washing. If this surface contaminationis not thoroughly removed, the new coating may exhibit poor adhesion tothe existing weathered coating. If a thorough brooming does not removethis tenaciously held dirt and soil, the coating should be scrubbedclean with a solution of TSP in water. All of the residue should thenbe rinsed from the roof with clean water and all excess water removed byvacuuming or blowing off with air. The roof surface should be thoroughlydry before the recoating operation begins. Prior to any washing operation,the coating manufacturer should be contacted for specific recommendations.

2.2 Priming Before Recoating

Priming may or may not be required before recoating. This decisionneeds to be made on a case-by-case basis. In instances where it isdifficult to determine if all adhered dirt or chalking has been removed,or if there is some doubt about the surface condition of the existingcoating, the surface should be primed with a tiecoat recommended by themanufacturer of the new coating. If the existing coating is in goodcondition, clean with no evidence of adhered dirt or chalk, the surfaceneed not be primed unless recommended by the manufacturer of the newcoating.

2.2.1 Where small spots of the coating not exceeding about 10% ofthe roof area have spalled, a primer should be applied to improve theperformance of the new coating system. This is effective in minimizingcracking of the new coating in surface transitions from foam to coating.

2.3 Repairs

Any defects in the coating or foam should be corrected prior torecoating in accordance with paragraphs 1.1 and 1.2.

A-3

r.

2.4 Recoating

After the surface has been properly cleaned and repaired, it shouldbe recoated. The coating system selected should be a high-qualityelastomeric coating for foam and should be applied in at least twocoats, in a "cross-hatched" manner, to give a minimum total dry filmthickness of 30 mils or at the coverage recommended by the manufacturerfor a new foam surface if greater than 30 mils.

3.0 Major Maintenance and Repair

If deterioration of the existing PUF roofing system is more advancedand more than 10% of the coating has spalled relatively uniformly overthe entire area, thereby exposing the foam, it is usually necessary toremove all coating and deteriorated foam until a foam surface of goodquality is obtained. The types of advanced coating deterioration couldinclude flaking or spalling, excessive blistering, excessive pinholing,cracking (due either to normal coating deterioration or hailstone damage),peeling, or extensive loss of adhesion to the foam. The cleaned, exposedfoam surface should be thoroughly inspected to be certain that alldegraded or poor-quality foam and coating have been removed and that theremaining foam contains no wet areas. Additional foam is then appliedand the new foam surface coated with a suitable elastomeric coatingsystem.

3.1 Removal of Larger Areas of Deteriorated Foam

If a larger area (over 15 ft2) of foam is badly degraded, of poor-o,4 quality, mechanically damaged, or wet, the foam in question should be

removed. The edges of the foam on the perimeter of the patch areashould be beveled with a disk sander; the area should be primed, ifnecessary, and then refoamed; and the foam surface should be coated witha suitable elastomeric coating system. Refoaming of these larger areasshould be done with regular foam spray equipment rather than the cannedfroth foam. Such removal and refoaming should be done in conjunctionwith the total maintenance of the roof (paragraphs 3.2 to 3.5).

3.2 Removal of Deteriorated Coating and Foam

If the coating is sufficiently friable, the removal of deterioratedcoating and foam can be achieved using a power disk sander. Some coatings,such as the urethane elastomers, retain a degree of their originaltoughness and abrasion resistance even though badly deteriorated. Insuch cases, the deteriorated coating and foam must be removed with amodified power lawn mower, a built-up roof spudding machine, or someother suitable method of mechanical removal. Following removal, if thefoam surface is excessively rough, the surface must be sanded lightly toprovide a smoother substrate for application of additional sprayed PUF.

3.2.1 Sanded Foam Surface. The sanded and cleaned foam surfaceshould not remain exposed overnight because it might absorb moisture.It is preferable to leave the newly sprayed foam exposed uncoated over-night rather than the sanded foam surface. Therefore, only that amount

A-4

, - . -a - , - t t ,q t. , , . . -. .- . . . . . -. . . . . . . . . . . . - . . - . - . . . .

of deteriorated coating/foam should be scarified that can be cleaned andrefoamed the same day. If the sanded foam surface must remain exposedovernight, it must be determined to be thoroughly dry by using a resistance-

* . type moisture meter before application of additional foam is permitted.

3.3 Cleaning of Sanded Foam Surfaces

Following the sanding operation the sanded foam surface should bethoroughly cleaned to remove all dust, dirt, or debris by vacuuming orblowing off with dry compressed air. The cleaned surface should beclosely inspected to determine that no foreign matter remains that mightadversely affect the adhesion of the new foam to the existing sandedfoam surface.

3.4 Priming Sanded Foam Surface

Priming of the cleaned, sanded foam surface before foaming, althoughnot absolutely necessary, does enhance the adhesion of new to sandedfoam. If a prime coat is recommended by the foam manufacturer, theserecoimmendations should be followed. This generally involves the use ofa light tiecoat.

3.5 Application of Additional Foam

An additional 1/2 inch or more of new PUF should be sprayed overthe existing sanded foam surface. The thickness of new foam to beapplied is dependent on the thickness of old (but acceptable) foamremaining and the required insulation thickness. The final foam thick-ness (old plus new) should be at least 1 to 1-1/2 Inches.

3.6 Coating of Refoamed Surfaces

The newly foamed surfaces should be coated with a high-qualityelastomeric coating system in the same manner and coverage as thatrecommended for a new P1W roofing system. The minimum recommendedcoating thickness is 30 mils dry, and the coating should be applied thesame day that the foam is applied. If "same-day coating" is not possible,the new foam should be coated the following day or within 72 hours atthe very latest.

3.7 Foaming Over Weathered Coating

New foam can be applied to a weathered coating of an existing foamroof in some cases. Each application must be considered on an individualbasis. When considering applying new foam over a weathered coating,(1) a specialized roof moisture survey should be conducted to establishthat the existing P1W roof is dry; (2) the existing P1W roofing systemshould be thoroughly inspected for roof defects; (3) any wet or degradedareas should be removed, the affected areas allowed to dry, and theremoved areas refoamed; (4) the weathered coating surfaces should bethoroughly cleaned and primed; and (5) the new foam and quality elasto-meric coating should be applied. Additional foam should not be appliedover an impermeable coating or over a silicone-coated foam roof.

-~ A-5

4.0 Complete Removal of Foam Roof Versus Major Maintenance

In the case of advanced foam roof deterioration, it may henecessary to remove the foam completely from the substrate iii prepara-tion for reroofing. Before the decision for complete removal andreroofing is made, however, the existing PUT roof should be thoroughlyexamined to determine the full extent of deterioration. It is possiblethat a sufficient quantity of acceptable-quality foam remains to make iteconomically feasible to remove only the degraded portion and refoam asdescribed in paragraph 3.7. If this is the case, it should be determinedthat the existing good foam is not wet before a final decision is made.This assessment can best be made with a nuclear moisture meter survey ofthe roof.

-A-

D)ISTIRIBUTION LIST

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Beach ('A: ('ode 102.5 II.hrarw Pune.t Sound. Firenitrron \ ,A (N 'isl 381). Pitiitiith. N A: ('ode 3s2".3.Pearl 1Harhor, Ill: ('ode 4111, Puget Soun1d: ('OdeC 441) Ptti~tioui Nil: ('ode 44)). Norfolk : ('tite 4-40. PI'trSound, Bremnerton WA: ('ode 453 1 tiI. Su~pr). Vallejo C(A ' CNo(mmiander. l'hilitdlhilt. PA: i-D. Nisian:hra rs. Portsmiouth Ni F'I PW Dept. loing Beach. (CAV PN'i) ('t isl 420111 )i r I'i irti ut 11. NA: i'D I)It'tde

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(juantanarniti Bat ('Uh: PNX't. Ketliask Iceland: PNNo. Nlavpirt IT. SILT. Gittamri 5(1. l'citrl I Itiltr Ill,SC'E. San itegor (' S('E. Stubic Bav. R. P.: . tilities Engr Off. Rout Spain

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4 ~~NRI. ('ode 58(14 Washingtton, D)C: ('Ode S441 (RA, Skiip). \\ :,-.himtit M

NR(IL( J,. ,.. Stephienson 1- (C. Bcrkle,%. ( AN ,NSC (ode S4.1 Norfolk. VANSD SCE. Subic Ba\. WPRI.

* NSWVSES (ode (1151 PortI hiuetenie ( ANW VC CC. C131.-41. Great LaikcN 11

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4331 (Brown). Newport RI: (ode IA 131 (G De 1,1 (ruI), Nex', loldonl C I

' ~~OFFICE SE('REIARYl OF DEFENSE ( 1.SI (NIRAM ) I r of I-voere'k - 'c1uoije D( i...iit* ONR Central Reiwonal Office. Boston. NMA. (ode 221, .No linitti,, \N V(ode 71 lot \Arlilltett N* PACMISRANF.-C III A-reai lie Sanlds. I'W( Kckaiha - Kiua III

PHIIBCB 1 P&E. San [Diego, (-APWNC ACE Of'fice Norfolk, NA: COI. (COICe 10I). OIaklaind. CA N:(ode 10, (irecit I ikes. 11 . ('oIc 11), likititilt.

CA:' ('ode 111). Gireat l-akes. II.: ('ode lilt(. Oakiland. ('N\: (OdeC 121. ( Ain (N ('i41 12N. (41.1111. (ideC

* ~~154 (Iibrar%(. Gireat Latkes. H- ('ode 2001. (Great Like, II,: (oe 21111. ( ~iiill (Oisl 4001. 1 lrua I .ikcs. It

Code 4M,41 Pearl H arbor, Ill. (OLIe -100. Sain Iio.CAN: ('ode 421(. ( irei I aikes. 11 : ode 4211. 1 Iaikiid.* V CA: ('ode 424. Norfolk. VA: ('ode 51111 Norfolk. N-: CICe 5115.- O(hilld. (.N. ( O'Id (,00, ( ireat l"1kes. 11

* Code 610,. San LDiego (Ca: (ode 7M14. Great Liikcs. IL:( 'COI7((1. Sanl DiCjeo. C-N:\ L \llits.Subhic Btl\-

RP: Library. C'ode 120lC. San Diego. (CA: Lihrar.\. (itiat: I ihrir , Noirfolk. N-N: I ihriirx. I'eal I arhoi . Ill:Librar'N, .Pensacola. FL: LibraryN. Subic Flax. R. P.: I ihrair, Yokosuka, 1,I ill IDept I R Paiia 1 Iearl

Hlarbor. FL Utilities Officer. (ijuami'aSPCC PW() (C'ode 1201) Meehanteshu11ri PA

SUPANX I'WO. Willjarllbure VATVA Smelser. Knoxville. Fenn- Solar Giroup, A -rnold. Knoxville, INUCV TWO OIC'. Port Iluenemne CA-U.S. MIERCHIANT MIARINIE-AADEMIY King.. Po int.- NY (Repint (uiodiani)USAF REGIONAL IIOSPITAL Fairchild AFB. WVAUSAF SC'HOOL OF AEROSPACE MlU!)l(INF flyerbani Mledicine Dn., BrooksNF3 I-,

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LSC'G R&D) ('ENTER I~ibrair' New London, CIUSDA Ext Service (I. Maher) Washington. L)C. Forest I'roducts Lab. Nlatdion W\I: Forest Service Reg 3 I R.

Brown) Albuquerque, NM: Forest Service. Bowers. Atlanta, 0A,USNA Ch. Mech. Enig Dept Annapolis MI): [N(RNG Di\', PN\I). Annapolvs MDr: L nerg\v-En i roll Study

Grp, Annapolis. MLD: Environ - Prot. R&DI Prog. IiJ. Williamts , Annapiili. Nil: Nlech. Etm~r. D~ept.- (CWill. AnnaF''Iis Mf): PW() Annapolis ML)D: ('SNA SYS ENGi DEPTI ANNAPLIS111 NIl)

USS FULTON V4PNS Rep. Olfr (W-3) Ne',v York. NY.4 ~ WATER & POWER RESOURC'ES SERVICE (Snmoak) Denxer. CO(

AMERICAN CONCRETE INSTITUTE Detroit MIl (I ibrary ()ARIZONA Kroclinger Ic mpe. AZ: State Energty Progranws Ott.. I'hoenix AZ.AUBURN UNIV. Bldg Sci Dept. ILechner, Auburn. AILBERKELEY PW Engr LDiv. Hlarrison. Lierkeley'. (CABONNEVILLE POWER ADMIN Portland OR ( Energ', (onsr',. OIL . 1). IDavexCAL.IF. DEPTI OF NAVIGATION & OCEAN L)EV. Sacramentii. (A (Gi. Arnistruote(CALIF. MARITIME ACAD)EMY Vallejo. CA I Lib-rary)C'LARKSON ('01L1 OF LECII Ci, Blson.11 P)Otsdanl NY('ONNECTICUT Office of Policy & Nlgt. Energy\. D~i\. Hartford. C'I

CORNEL.L UNIVERSITY Ithaca NY (Serials Dept. Engr l.it) ): Ithaca, NY (( oil & I-mtiton. Lngt)DAMES & MOORE LIBRARY LOS ANGELES. (CA

* . DRURY C'OLL.EGE Plhysics LDept. Springfield. MO* * DUKE UNIV MEIC AL (ENILR B3 NLLu'i. D~urham N(

UNIVERSITY OF DELAWARE (LDr S LDexter) I.e',',c, 1)[E

F(OREST INSTl. F(OR OCEAN & MOII - IA IN (arsoin ('It\ N\ ( Studies -I hr,ir\,* ~~~GEORGIA INS-------OF: IE('IIN0fI() (H. R, Johnson) .-Nlait. GA CNo(l -Nrch. Hliont. Ntlitt. GjA

HARVARD U NIV. LDept of1 Architecture. IDr. Kim., ("0lnthridee. NIA

HAWAII STIATE D)EVI OF PL AN. & 1.0'(N I)EN I lonolulu Ill i tech lIn! ('tr)IOWA STAlE UNIVE RSIIY LDept. Arch. McKriwn. Ai,ts. IAWOOD)S HOL.E OCEAN(I( RAPI IIC INS I W~oods i le N1A I titect

KEENE STIATE CO(LLEGiE Keene NI I (( unninitinLEFIIGII UINIVERSITIY [it:IIlEHIENI. PA INIARINI (it() I I ICI INI \1N I ABl RI( I I NRD)I. 1I, thiclient

PA (Linderman Ijb. No.3(1. Flecksteiner(

LOUISIANA D)IV NI RAE_ RI:S( ) RUFS & INEFR(N DYi%) ( )I R&DI) li'o"1 Ro~lc. INMAINE NIARITIME ACADEFMY (AS lINIK NL I IIR*R'iMAINE OFFICE OF ENERGY RESOURCES .NAustqa. N1lMICHIIGAN TECIINOIOC6ICAI. 1,NINERSIIY Ilooightm. Ni 11~a.MISSOURI ENERGY AG;ENCY Ictlerson Cit% MOCMIT manrdcM:Crbridge MIA (kmn 1)1-5(1(. [ccli. Relor is. I nr 1 0,

MONTANA ENERGY OFFICE Anderson. fI elera. NI VNATU~iRAL- ENERGY LAB Library\. lIIonolulu. IIINEW HA.MPSIIIRE Concord NH- (C overnor , Council on E~ncrL!\

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%1 .1 STATE UNIV. OF NEW YORK Buffalo. NY: Fort Schuvier. NY' (Lorwobardi)TEXAS A&M UNIVERSITY W.B. Ledbetter College Station, 1X

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SUBJECT CATEGORIES 1s ENEIGY/POWFR GENERATION29 Thermal conservation (thermal engineering of buildings. HVAC

I SHORE FACIUTIES systems, energy loss measurement. power generatron)2 Construction methods and materials including crrosion 30 Controls and electrical conservatron (electrical systems,

control. coatings) energy monitoring and control systems)3 Waterfront structures (maintenanceldeter oratIon control) 31 Fuel flexibility (liquid fuels. coal utilization, energy4 Utilities (including power conditioning ) from solid waste)5 Explosives safety 32 Alternate energy source (geothermal power, photovoltaic6 Construction equipment and machinery power systems, solar systems, wind systems, energy storage7 Fire prevention and control systems)8 Antenna technology 33 Site data and systems integration (energy rr source data. energy9 Structural analysis and design (including numerical and consumption data, integrating energy systems)

computer techniques) 34 ENVIRONMENTAL PROTECTION10 Protective construction (including hardened shelters. 35 Solid waste management

shock and vibration studres) 36 Hazardousitoxic materials managementS11 Soil/rock mechanics 37 Wastewater management and sanitary engineering13 BEQ 36 Oil pollution removal and recovery

N. 14 Airfields and pavements 39 Air pollutionIS ADVANCED BASE AND AMPHIBIOUS FACILITIES 40 Noise abatement16 Base facilities (including shelters, power generation. water supplies) 44 (WEAN ENGINEERING17 Expedient roads/airfields/bridges 45 Seafloor soils and foundations

it - 18 Amnphibious operations (including breakwaters, wave forces) 46 Seafloor construction systems and operations (including, 19 Over-the-Beach operations (including containerization, diver and manipulator tools)

materiel transfer. lighterage and cranrs( 47 Undersea structures and materials20 POL storage, transfer and distribution 48 Anchors and moorings24 POLAR ENGINEERING 49 Undersea power systems, electromechanical cables.24 Same as Advanced Base and Amphibious Facilities. and connectors

except limited to cold-region environments 50 Pressure vessel facilities51 Physical environment (including site surveying)

4 52 Ocean based concrete structures1.3 Hyperbaric chambers

1 54 Undersea cable dynamicsTYPES OF DOCUMENTS

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