Building Details of a Tabique Dwelling in Trás-os-Montes e Alto Douro Region

Rui Cardoso 1

Anabela Paiva

2

Jorge Pinto 2, 4 , 3

António Murta 2 Humberto Varum 5

Lina Nunes 6 Luís Ramos 2

ABSTRACT Tabique is one of the main Portuguese traditional building techniques which use earth as a building material. In general, a tabique building component is formed by a simple timber structure covered by an earth based mortar on both sides. The mortar has an important role in this system because it protects the internal timber structure as well as it is a coating. Trás-os-Montes and Alto Douro, is the northeast region of Portugal and it is rich in terms of tabique heritage construction. Meanwhile, previous research works have shown that the existing tabique constructions, in this region, show a generalized advanced stage of deterioration. This aspect associated to the fact that there is still a lack of scientific studies done in this field motivated this research work, which its main objective is to identify and to understand the structural system of tabique dwellings. A two storey tabique dwelling located in Lamego Municipality, near Douro River, in the UNESCO classified heritage area, is used as reference in this study. Building details of the original applied structural system solutions are shown and described. The adopted connection solutions between structural components are some of the above building details which are introduced and described. Finally, the conservation stage of these elements is also analysed. KEYWORDS Tabique, building detail, raw materials, traditional building techniques, EC5 1Coimbra Polytechnic Institute, Oliveira do Hospital Technology and Management Superior Scholl, Oliveira do Hospital, PORTUGAL, rui.cardoso@estgoh.ipc.pt, http://www.estgoh.ipc.pt. 2Trás-os-Montes e Alto Douro University, Vila Real, PORTUGAL, apaiva@utad.pt, tiago@utad.pt, lramos@utad.pt. http://www.utad.pt. 3C-MADE, University of Beira Interior, Covilhã, Portugal 4Associated Laboratory I3N, 3810-193 Aveiro, Portugal 5Aveiro University. Aveiro, PORTUGAL, hvarum@ua.pt, http://www.ua.pt. 6Núcleo de Estruturas de Madeira, Laboratório Nacional de Engenharia Civil (LNEC), Lisboa, PORTUGAL, linanunes@lnec.pt.

R. Cardodo, J. Pinto, A. Paiva, A. Murta, H. Varum, L. Nunes and L. Ramos.

2 XII DBMC, Porto, PORTUGAL, 2011

1 INTRODUCTION

A tabique building component such as a wall, is formed by a timber structure covered by an earth-based mortar on both sides, equivalent to wattle and daub in England or torchis in France, Minke [2006] and Torgal & Jalali [2009]. Previously research works Pinto et al. [2010] and Cardoso et al. [2010], for instance, focused on the study of the tabique building technique in Trás-os-Montes e Alto Douro region, indicate that a tabique wall may have a structural function apart of only being a partition element. According to Pinto et al. [2009], it was concluded that the most common building materials used in this context are the pinus pinaster for the timber structural elements, a sandy-clayed based mortar for the filling and coating, and steel nails for the connection between timber elements. This research work is part of a study of the tabique building technique used in the region of Trás-os-Montes e Alto Douro. This region is the northeast part of Portugal. There is a significant incidence of this traditional Portuguese building technique in this region, Carvalho et al. [2008] and Martinho et al. [2009]. Until early XX century, before the massive introduction of the reinforced concrete, this building technique was very relevant. In this region, there are several examples of tabique dwellings that have stone masonry as exterior walls at the ground floor level, and tabique exterior walls at the first floor, Cepeda et al. [2010]. This paper intends to describe building structural details adopted in a tabique dwelling located in Lamego Municipality which was considered as a reference of the above feature. This information may contribute for a better understanding of this traditional Portuguese building technique and, therefore, may give guidance for future rehabilitation building processes. This paper is structured as follows: Firstly, the location of the tabique dwelling used as reference is done; Secondly, a brief description of this building is delivered and also the description of the adopted overall main structural system solution; Thirdly, some used building details solutions are introduced and described. Finally, the main conclusions are drawn. During this sequence, the level of conservation of the different structural elements is commented. 2 LOCATION OF THE TABIQUE DWELLING As it was stated above, a tabique dwelling was used as a reference of a tabique dwelling of two floors which has exterior tabique walls at the first floor level. This is one of the most common solution types in this region. The other common solution type is a tabique dwelling of two floors, having exterior stone masonry walls and tabique partition (or interior) walls. The tabique dwelling used as reference is located in this region, in the Douro North Valley Municipalities Association, in the Lamego Municipality and according to Fig. 1. The GPS coordinates of the precise location are: latitude of N 41º 09.230’ and longitude of W 7º 47.117’.

Figure 1. Tabique dwelling location 3 OVERALL STRUCTURAL SYSTEM SOLUTIONS The frontal view of the studied tabique dwelling is shown in Fig. 2. Its age is over 100 years old. It is a two floors dwelling (ground and first floors), having an attic. The exterior walls are stone masonries and tabique at the ground and the first floors, respectively. All the interior walls are tabique. From

Building details of a tabique dwelling

XII DBMC, Porto, PORTUGAL, 2011 3

Fig. 3 it is noticed that there is no interior tabique wall at the ground floor level, this is a common building solution among the tabique building already studied. It is evident from Fig. 2 that this dwelling presents an advanced level of deterioration. This fact is in accordance with the results reported in previous works Cepeda et al. [2010] which highlight for the urgency of conservation demand that this type of buildings are requiring.

Figure 2. Tabique dwelling used as reference

Openning

II

I

C

L

1 floor

Ground-floor

st

A

A - Roof t imber st ructureB - Top roof beam

F - Tabique part it ion wall

F

G - 1 Floor t imber st ructure

C - Tabique resistente wall

Door

G

DoorF

C

GL - Stone masonry wall

G

D

D - Wall plateE - Ceiling t imber st ructure

H H - Floor plate

Tiles

50 cm

E

B

J

st

J - Ground Floor t imber st ructureDoor Door

F F

F

F

Ceiling

C

C

L

Figure 3. Cross section

The main structural solution is formed by exterior stone masonry walls located at the ground floor level (detail L, Fig. 3) which support timber beams which are part of the timber structural system solution of the 1st floor, (detail G, Fig. 3). This floor also includes boards or secondary beams and the flooring, (detail G, Fig. 3). Meanwhile, exterior tabique walls are supported on the beams of the 1st floor (detail II, Figs 3 and 12 c)), at the 1st floor. The floor of the ceiling has a similar timber structural

R. Cardodo, J. Pinto, A. Paiva, A. Murta, H. Varum, L. Nunes and L. Ramos.

4 XII DBMC, Porto, PORTUGAL, 2011

solution as the 1st floor but inverted, (detail E, Figs 3 and 4 b)). The timber structural solution of the roof is beam type (i.e. 3 hinged arch), detail A of Fig. 3, this structure supports on the beams of the ceiling floor. There is also a timber paving at the ground floor level (detail J, Fig. 3) which its structural solution is similar to the one adopted in the 1st floor pavement. This structure is not in direct contact with the ground, as Fig. 3 illustrates. The adopted building detail solutions are introduced and described in the next section. This description is done from the top to the bottom. Therefore, building details concerning the solution applied at the roof and ceiling levels are delivered followed by the description of building details related to the tabique walls. These building details related to the tabique walls are the connections between the exterior walls and the ceiling and the roof, the connection between the exterior wall and the 1st floor and the exterior masonry wall, the orthogonal junction between exterior and exterior walls, and the orthogonal junction between an interior and an exterior wall. Finally, building details related to the timber floors are also introduced. 4 BUILDING DETAILS 4.1 Roof and ceiling level The roof structural system is shown schematically in Fig. 4 a). The ceramic tiles (A1) are supported on the tile batten (A2) and these ones are supported on the rafter (A3). On the other hand, these last ones are supported at the bottom edge on the wall plate (D) and at the top edge on the top roof beam (B). Two primary timber roof beams, in the same cross section alignment form the 3 hinged arch mentioned above. Meanwhile, Figs 4 b) and 4 c) illustrate the building connection detail between the roof structural system and the external timber walls located at the first floor level.

Roof st ructureD

B

D- Wall plateB- Top roof beam

A3A2

A1

A3- RafterA2- Tile bat tenA1- Tile

a) Roof structural system b) Detail I.1

E1

E2 E3

F 10 cm

A3

A2

A1

D

E1 - Tie beamE2 - Ceiling joistE3 - Ceiling

D - Wall plateA3 - RafterA2 - Tile bat tenA1 - Tile

c) Detail I.2

Figure 4. Roof structural system solution 4.2 Tabique walls The exterior and interior tabique walls (C and F of Figs 3 and 5) of this dwelling have as timber structural solution vertical elements connected by horizontal ones (i.e. laths), Fig. 5, the horizontal laths helps to support and hold in place the earth based mortar and are used as structural element. This

Building details of a tabique dwelling

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is precisely the most common timber structural solution used for tabique building components in this region, Pinto et al. [2010]. From Fig. 5, it is also noticed that these timber elements present a very good level of conservation which contrast with the overall building that is almost reaching the collapse as Fig. 2 shows. We strongly believe that the earth based mortar which completely covers the timber structural elements of the tabique walls is able to protect the timber structure. Furthermore, in the interior of the tabique walls it was found small peaces of wood which probably resulted from the building process of the main timber structure. This building waste was used to fill the existing gap between the vertical timber elements and as Fig. 5 b) highlights in detail III.

a) Exterior b) Interior

Figure 5. Tabique walls The shape of the cross section (detail IV) and its respective average dimensions of the laths of an exterior wall is shown in Figs 6 a) and b), respectively. Meanwhile, the endings of the laths are mismatched among them as Fig. 6 c) indicates along the vertical direction. This aspect is interesting because it suggests that a tabique component may fulfil the conditions prescribed by the EN1995-1-1 [2004] for a load-carrying capacity of systems in which the horizontal timber elements may work as a load distribution system.

2.2

1.0

1 .0

[cm]

a) Cross section shape b) Dimensions c) Mismatched of the endings

Figure 6. Lattice work of the tabique walls The building connection between tabique walls, exterior (C) and exterior (C), and exterior (C) and interior (F) details are presented schematically in Figs 7 a) and b), respectively. The last vertical timber element of each exterior walls connect directly, the horizontal timber elements (i.e. laths) are intercalated. In order to figure out these details it was necessary to remove the coating of earth based mortar locally as Fig. 7 shows. This aspect and the very bad conservation level of the building (unsafe fieldwork), were the main reasons because it was not possible to collect data related to all the building details.

CC

q

F

C

a) Exterior (C) and exterior (C) b) Exterior (C) and interior (F)

Figure 7. Connection between walls

R. Cardodo, J. Pinto, A. Paiva, A. Murta, H. Varum, L. Nunes and L. Ramos.

6 XII DBMC, Porto, PORTUGAL, 2011

In Figures 6 a) and c) it is noticed that the connection between vertical and horizontal timber elements are materialised by metal nails which correspond to the most common solution as already reported in Pinto et al. [2010]. It was also stated there that usually it is used steel nails. In this paper, we are presenting in Fig. 8 a building solution detail of the connection between an exterior tabique wall and the floor. The vertical timber elements of the external tabique wall are connected to the floor plate or wall plate (H) by metal nails (V) and according to the detail delivered in Fig. 8.

HC

Nail

Figure 8. Connection between external tabique wall and the floor

4.3 Floors As it was stated above, in general, the timber floors and, in particular, the first floor has the following structural solution: the main or the principal beams are directly supported on the masonry walls; the boards or the secondary beams are supported on the previously ones; the flooring boards are supported on the secondary beams; the floor plates are supported on the principal beams and, on the other hand, support the exterior tabique walls. The main timber floor beams, G3 in Fig. 9, are simple supported directly to the top edge of the exterior masonry walls. The support length corresponds to the thickness of the wall and as Fig. 12 documents. In this particular case, it corresponds to a 0.60 m average thickness. Fig. 9 b) and c) also gives guidance to realise how the connection between exterior tabique wall and the pavement is done (detail II of Fig. 3) and complements the description done related to Fig. 11. In Fig. 9 b) the main timber floor, the floor plates and the vertical timber elements of the wall are clearly identified as well as, their disposition among them. The outer face coating of the walls have completely deteriorated and disappeared in this part of the walls and this is the reason because the main timber beam top surface is exposed to the outside, Fig. 9 b). In normal conditions, it should be covered and protected with the earth based mortar.

C F

G3

G2

G1

H - Floor plate

H

F - Tabique part it ion wall C - Tabique resistente wall

G1 - FloorG2 - Secondary floor beam

L - Stone masonry wall

G3 - Principal floor beam

MM

10 cm

L M - Skirt ing board

(a) The beam

(b) The support (c) Detail II

Figure 9. The main timber floor beams

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5 CONCLUSIONS The main structural system solution of an ancient tabique dwelling located in Lamego was presented and described. This system comprises exterior stone masonries walls, tabique exterior and interior walls, timber pavements and roof. The usage of timber structural elements is very expressive. These elements were used basically in the upper floors avoiding the direct contact with the ground. Some building details specific of this dwelling were presented and described throughout this paper. These details were essentially focused on the connection between components. For instance, the connection between the roof structure and the exterior tabique wall, the connection between the exterior tabique wall and the floor, the connection between the floor and the exterior stone masonry walls were presented. Furthermore, details of tabique walls were also delivered and compared with the results of previously reported research works done in this subject. It was concluded that there is a consistence in this aspect. This paper also highlights the fact that a tabique component may guaranty the prescribed conditions by the EN1995-1-1 [2004] for a load-carrying capacity of systems in which the horizontal timber elements may work as a load distribution system. These details also show a sustainable building procedure which consists on reusing timber waste for the filling of the tabique walls. It was noticed that the dwelling used as reference presents an alarming deterioration level almost reaching the ruin. However, it was simultaneously noticed that the timber elements located in the inside and, in particular, the ones still covered by the earth based mortar present a very good level of conservation. The safety conditions for performing the field work were not the convenient ones. This fact hugely limited the data collecting task. REFERENCES Cardoso, R., Damião, C., Pinto, J., Paiva, A. & Varum, H. 2010, ‘Caso de Estudo de Aferição do Potencial da Aplicação de Terra Local na Reabilitação de Construções de Tabique’ , Proc. VII Congreso Internacional de Arquitectura de Tierra, Tradición e Innovación. Cuenca de Campos, Valladolid, 25-26 de Setembro de 2010. Carvalho, J., Pinto, J., Varum, H., Jesus, A., Lousada, J. & Morais, J. 2008, ‘Construções em Tabique na região de Trás-os-Montes e Alto Douro’ CINPAR 2008 – 4th International Conference on Structural Defects and Repair. Civil Engineering Department – University of Aveiro. Portugal. 25-28 June 2008. Editors: Humberto Varum, Francisco Carvalho, Aníbal Costa, Alexandre Bertini, Petr Stepánek. ISBN: 978-989-95695-3-9. Cepeda, A., Murta, A., Lousada, A., Vieira A., Pinto, J., Fernandes, L., Tavares, P., Silva, P. & Varum, H. 2010, ‘Tabique construction in Alto Tâmega’. Book of abstracts of the 1st International Conference on Structures and Architecture (ICSA2010). Ed. Paulo Cruz. CRC Press, Taylor & Francis Group. London. ISBN 978-0-415-49249-2. pp. 397-398 EN 1995-1-1: 2004. Eurocode 5: design of timber structures – part 1.1: general rules and rules for buildings. European Committee for Standardization, Brussels, Belgium, (E). Martinho, J., Gonçalves C., Magalhães, F., Lousada, J., Vieira, J., Varum, H.; Tavares, P. & Pinto, J. 2009, ‘Construção de Tabique no Vale do Douro Sul’. CD do VIII Seminario Iberoamericano de Construcción com Tierra (VIII SIACOT) e do II Seminario Argentino de Arquitectura y Construcción com Tierra (II SAACT). Editor: CRIATIAC – FAU – UNT. Tucumán, Argentina, Junho de 2009, pp. 514 - 521.

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Minke, G. 2006, Building with Earth, Design and Technology of a Sustainable Architecture. Birkhäuser – Publishers of Architecture, Basel-Berlin-Boston. ISBN 13: 978-3-7643-7477-8. Pinto, J., Varum, H., Cruz, D., Sousa, D., Morais, P., Tavares, P., Lousada, J., Silva, P. & Vieira, J. 2010, ‘Characterization of Traditional Tabique Constructions in Douro North Valley Region’. Journal WSEAS Transactions on Environment and Development, ISSN 1790-5079, 2, pp. 105-114. Pinto, J., Varum, H., Cruz, D., Sousa, D., Morais, P., Tavares, P., Lousada, J., Silva, P. & Vieira, J. 2009, ‘Tabique Construction Characterization in Douro North Valley, Portugal: A First Step to Preserve this Architectural Heritage’, 2nd WSEAS International Conference on Urban Rehabilitation and Sustainability (URES'09) - Environmental Science and Sustainability - Proceedings published by WSEAS Press (printed and in CD), Editors: Manoj Jha, Charles Long, Nikos Mastorakis, Cornelia Aida Bulucea, ISBN 978-960-474-136-6, ISSN 1790-5095, Baltimore, USA, 7-9 de Novembro de 2009, pp. 48-53. Torgal F. Pacheco, Jalali Said et al. 2009, A construção em Terra. Ed. TecMinho. Universidade do Minho, Guimarães 2009. ISBN 978-972-8692-40-7.