The restoration of the roof of the Gothic Cathedral

255
Chapter 1 Rehabilitation of historical sites, buildings and structures
The restoration of the roof of the Gothic Cathedral of Tortosa
J. Lluis i Guinovart, A. Costa i Jover, S. Coll i Pla & J. M. Toldrà i Domingo
Rovira i Virgili University, Reus, Spain
doi: 10 14575/gl/rehab2014/027
ABSTRACT: The Meridional gothic architecture (XIV-XVth) is characterized by flat roofing.
The new imaging defined in the Council of Trento (1545-1563) imposed more importance to the
Renaissance city, as a new symbolic reference in the urban space. In the case of the Gothic
Cathedral of Tortosa, the new reference with inclined roofs and water filtration problems caused
the modification of the original flat solution of the cover. The typological and physical
assessment revealed the constructive layers overlapped in the roof. This case is an example of
restoration where the starting gothic profile has been restituted. The paper exposes the
theoretical framework of the heritage intervention criteria, as well as the constructive solution
given for the new roof of the Cathedral of Tortosa.
1 INTRODUCTION
The protection against water is one of the most critical subjects in the design and maintenance
of any construction. In that sense, the large dimensions of Gothic Cathedrals represent a great
technical challenge. Traditionally, the French gothic solves the problem with timber roofs with
great inclinations. On the other hand, Meridional gothic uses flat solutions since the climatology
and the constructive tradition are different. These flat solutions have water filtrations with time,
and most of the temples have suffered several reparations.
The Cathedral of Tortosa is not an exception. Several interventions radically changed the
look of the building through years, but the problem of rain water filtrations was not solved.
Restorations are documented since XIXth century, and the present paper exposes the last process
of restoration of the covering, which took place in the late nineties.
1.1
Chronology
The Cathedral Chapter of Tortosa commissioned in 1346 a new cathedral (Fig. 1) to master
Bernat Dalguaire, which had to replace the old Romanesque building. The heptagonal chevet of
Tortosa Cathedral were built and covered on first place between 1374 and 1441. It has an apse
with double ambulatory arranged on the outside of the old Romanesque Cathedral. The process
was documented into “llibres d’obra” (cathedral construction accounts) (11.o.ACTo) (Almuni,
2007). It was built the radial chapels on first place, covered consecutively from the gospel to
epistle between 1383 and 1424. The initial section, with a proportion of 9/5, was unusual in late
256
REHAB 2014
R. Amoêda, S. Lira & C. Pinheiro (eds.)
XIVth century. It is explained because the walls between radial chapels were eliminated (Lluis,
2009). In the second phase, the ambulatory was built between 1424 and 1435. An increasing
section and change of construction method takes place at this moment. The proportion of the
section changes to 9/6 and the ambulatory vaults are covered symmetrically, over presbytery
axis, closing from the mouth to the interior (1432-1434). The third and final phase corresponds
to the covering of the presbytery (1435-1441). The main keystone were placed first, and after
the vaults were built (Lluis; Almuni, 2011). The temple was consecrated for the first time on
April 12, 1441. The fortified citadel concept is evident in the initial design of the gothic
cathedral. An example is the battlements of the walls on top of Saint Pedro and Saint Pablo
chapels, which will be repeated in all the naves. The flat profile of the covering is finished with
lime mortar, as a kind of opus ceamenticium (Fig. 2). The first references to the construction of
the nave date from 1429, and there is a lack of information until 1440. The construction was
developed over several centuries, until the construction of the baroque façade completed in
1757.
Figure 1. Santa Maria de Tortosa Cathedral (J.M. Roselló, C. Borràs).
2 MATERIAL AND METHOD
In order to establish the restoration criteria, it was necessary to determine the existing
constructive layers and also to identify the original constructive solution. Thus, the data
obtained through the typological and historical assessment is combined with the physical
evidences found in the survey of the covering.
2.1 The covering in Meridional gothic
The new imaging defined in the Council of Trento (1545-1563) imposed a greater importance to
the Renaissance city, as a new symbolic reference in the urban space. The new visual reference
with inclined roofs attempted to reproduce the imaginary of Constantine times, laqueada tecta,
Liber I. Chap. V De tecto (Borromeo, 1859: 27-29).
This aesthetic (and construction typology) flat roof has been assessed as a main characteristic
of Meridional Gothic. G.E. Street (1824-1881) highlights the singularity of the flat roof of
Barcelona Cathedral (Street 1865: 32). R. Lasteyrie (1849-1921) is strange by the flat roof of
southern France cathedrals as a Saint-Nazaire de Carcassone, Beziers or Burdeos. These
cathedrals have a cover supported by vaults as in Roman times. E. Viollet-le-Duc (1814-1879)
understands the terraces of the cathedrals models in the French Midí (Clermont, Limoges and
Narbonne) as an evolutionary characteristic of the Northern Gothic builders (Viollet-le-Duc,
1854-1868, 2: 372-375). V Lamparez (1861-1923) determined the monumental difference
Chapter 1 Rehabilitation of historical sites, buildings and structures
257
between Castilla and Aragon. Hall church (hallenkirche) typology and stepwise section of the
flat cover (Lamperez 1909, 190 bis Lam.III) were common in the Aragon Crown (Catalunya,
Valencia, Aragón).
Josep Puig i Cadafalch (1896-1956) will consider these cathedrals as the origin of the
influence of Northern Cathedrals in the Catalan Gothic (Puig i Cadafalch, 1921). Hans Meyer
Thesis (1896-1984) assumes the difference between Meridional Gothic and French and English
models of cathedral (Sedlmayr 1950). Some authors shaded this concept, as the Catalan Gothic
is different to other Meridional models (Bofill, 1977: 39-49). Thus, Meridional Gothic, in a
country with a different weather from European, presents two typological characteristics: flat
cover and smaller windows (Zaragozá, 2000) (Fig. 5).
Figure 2. Original Gothic finishing, trespol (Cob. A).
From a structural point of view, this cover presents a complex mechanical system, because
large weight of concrete is placed over the space. Leopoldo Torres Balbás (1888-1960) checks
the structural function ogives and jitters (Torres Balbás, 1939, Torres Balbás, 1945). The roman
traditional models gave form to Roman medieval vaults (Basegoda Nonell, 1977: 287-382).
Arturo Zaragozá has discussed again the concept of the structural model, proposing that the
vault works with the lime mortar coat on top.
Some authors have seen through this constructive system the connection with the Roman
building tradition, Bassegoda Amigó (1944), Torres Balbás (1946), Bassegoda Nonell (1977) or
Zaragozà Catalán (2008). This configuration of religious buildings evolved towards a model
with timber inclined roofs, because of the influence of Instrucctionum fabricae et suppellectitis
ecclesiasticae libri duo (1577) promoted by Carlo Borromeo (1538-1584), which lead to a
formal transformation of the top of the buildings.
2.2 Sample of the roof
A sample (1996) made during the drafting of Master Plan (1995-2000), revealed the original
covering of the Cathedral. Juan Bassegoda Nonell (1930-2012) defined this construction system
as Catalan gothic vault. This constructive solution can be finished with trespol or ceramic tiles
over a flat or inclined surface. It has been used in many buildings along the Aragon Crown, and
in the city of Barcelona it has been studied in: Barcelona Cathedral, monastery of Pedralbes,
Santa Maria del Mar, Santa Cruz hospital or the church of Santa Maria del Pi (Bassegoda
Nonell, 1989a pp. 133-146; Basegoda Nonell, 1989b, 30-38).
This construction technique lightens the weight of the cover, and is usually found in East and
South of Iberian Peninsula. It is mentioned in the construction accounts of Barcelona cathedral
(Carreras, 1914: 132-133), Mallorca cathedral (Domenge, 1999: 288) or Tortosa (Almuni, 1991:
258
REHAB 2014
R. Amoêda, S. Lira & C. Pinheiro (eds.)
165, 181-182, Almuni, 2007: 135,186). An archaeological sample made in Tortosa Cathedral
revealed similar constructive solutions as in Santa Maria de Alicante (Borrego; Saranova, 1994,
181-198), Mallorca cathedral (Gonzalez, 1987, 469-482) or in Sevilla (Jimenez, 2000, 561-567).
Figure 3. Ceramic lightning of Gothic cover (J. Lluis i Guinovart).
Figure 4. Cover section of Tortosa Cathedral (J. Lluis i Guinovart).
3 THE RESTORATION OF THE ROOF OF THE CATHEDRAL OF TORTOSA
3.1 Background
The profile of the covering was changed during XIXth century. In 1800, an architect was called
to assess the existing cracks over the sacristy and collateral naves1. The Chapter decided to
cover all the naves with an inclined roofing system in 18032, although the cracks are
concentrated only in Catalan-style covers. The new cover will affect the areas finished with
“trespol”. The arab-style tiles have a good waterproof behavior, but the new solution caused
cracks in the encounters with masonry walls because of the differential thermic expansion of
Chapter 1 Rehabilitation of historical sites, buildings and structures
259
stone and lime mortar. It is reported in the Cathedral Construction Accounts the repair of water
filtrations and cracks in the roof by the master.
So, the first reform of the roof was made with arab-style roofing tiles. The new solution was
laid over a timber frame with an inclination of 38.8 %, while in the lateral naves it was built
over a rubble infill. The inclination in this case was 8% because the hip line was limited by the
high of the windows. It is too small to use arab-style tiles, and caused waterproof problems
because of the overlap of the tiles. Thus, the water filtrations caused the saturation of the
rubbish infill. Moreover, the new inclined cover sealed the upper ventilation system. These two
problems may cause condensations.
Figure 5. Santa María de Tortosa Cathedral cover (1996).
Discuss about the cover restoration started in seventies. The Chapter, represented by Mn.
Aurelio Querol Lor (1917-1994) asked Juan Bassegoda Nonell (1930-2012) for advice, as he
knew the constructive technique and the original section of the gothic cathedral. Joan Bassegoda
Nonell advised the inclined cover instead of the traditional Catalan cover solution of flat tile
because it has larger expansions and it can generate troubles in vertical masonry walls junction.
For this reason, most of the roof of the central nave was replaced (1975). It was previously
restored after the Spanish Civil War (1936-1939) by the program Regiones Devastadas (1940),
but the new timber frame had a different stiffness from previous sections. Then, the critical
areas of the lateral naves were not restored.
The problem was not solved, and at nineties, the Generalitat of Catalunya Culture
Department commissioned a study about the state of the cover to the architect Alfonso Llorca i
Martí, who advised a new intervention recovering the flat roof. The problem became worse after
the heavy rains of between 5 and 8 December 1996, during the Pontifical Eucharistic
celebration of the Inmaculada Concepción. Thereafter, the Chapter commissioned a study to
Josep Lluís i Guinovart, which was sent to the Spanish Ministry of Culture. It ordered an
emergency restoration of the cover (1997). The Chapter, chaired by Mon. Manuel Garcia
Sancho (1924-2000) resolved the question of the three last decades: they decided to recover the
original flat roof.
3.2 The restoration
The emergency restoration was made between 1997 and 1998. The finishing material was not
defined in the theoretical flat cover solution. The solution proposed so far was the use of a flat
tile covering with a color like the existing arab-style tiles. It is a Catalan Roof System, already
260
REHAB 2014
R. Amoêda, S. Lira & C. Pinheiro (eds.)
used in the last bays of the nave (1494-c. 1600). On the other hand, the solution with the
technique trespol was used in the first stages of the construction, between 1383 and 1494, until
the first masonry joint. The solution finally proposed for the restoration uses a finishing with
chromatic proprieties similar to the opus ceamenticium covering. The solution is an inverted
cover, which recovers the initial flatness of the roof, and enables the drainage of rain water
below the finishing with artificial stone tiles.
The constructive section has a provisional layer of separation and waterproofing which
allows the execution of following stages, protecting the original cathedral cover. Next, a mortar
layer will enable the cover to be trafficable. A leveling layer is placed over it, built with low
density concrete (200kp/m³) based on EPS balls, where it is embedded the drainage network of
rainwater. Over this cover it was installed the PVC water proof layer with a thickness of 1.5mm,
plasticized with polyester fiber armor. This layer completed the provisional waterproofing
before the final solution is built.
Figure 6. Constructive detail of the new solution.
The inverted cover is composed firstly by a waterproofing layer, built with extruded
stonewear tiles with natural klinker and low water absortion. Above this layer, it is placed a
XPS isolation membrane to avoid expansions, a geotextile layer with a density of 300 kp/m³ and
finally a 15 cm gravel layer. It will allow the passage of the necessary electrical lines, both
indoor and outdoor lighting, as well as water pickups for the maintenance of the covers. The
whole passage facilities is made with registrable boxes which allow access to the drainage
network of rainwater and its corresponding cover drains, also registrable for maintenance.
Chapter 1 Rehabilitation of historical sites, buildings and structures
261
Figure 7. Santa María de Tortosa Cathedral Cover (1999).
4 CONCLUSIONS
The assessment of the cover form a historical, typological and physical point of view, revealed
the original solution of the masters. Thus, the restoration had the purpose of recovering the
original gothic profile of the cathedral of Santa Maria of Tortosa.
The restoration discussed and concluded the main premises postulated by several Chapters
and architects during the last thirty years. The constructive solution built can be defined as an
update of historic constructive techniques. The lower solution with traditional Catalane-style
Cover is used to waterproof, and its upper isolation minimizes the expansions of the material.
Moreover, the new solution restores the appearance of the gothic cover. The finishing layer
recovers the profile and chromatics of the XIVth century roof, at the same time that the old and
new elements are perfectly distinguishable.
ENDNOTES
1
The May 25, 1800 an architect is reported to analyses the Sacristy and Dulce nombre de Jesús chapel,
Chapter Archive of Tortosa 1800-1801, (vol.217, fol. 15v).
The June 23, 1803 the roofing of cathedral of Tortosa is decided, Chapter Archive of Tortosa 18021803, (vol.218, fol. 27r).
ACTo. - Chapter Archive of Tortosa (abbreviation of Archivo Capitular de Tortosa).
2
REFERENCES
Almuni, V. (1991). L’obra de la Seu de Tortosa (1345-1441). Tortosa: Cooperativa Gràfica Dertosense.
Almuni, V. (2007). La catedral de Tortosa als segles del gòtic. Barcelona: Fundació Noguera.
262
REHAB 2014
R. Amoêda, S. Lira & C. Pinheiro (eds.)
Bassegoda Musté, B. (1944). Racionalismo a ultranza en la arquitectura ojival. Separata Memorias de la
Real Academia de Ciencias y Artes de Barcelona. Tercera época, núm. 504, vol. XXVII, núm. 4.
Barcelona: Real Academia de Ciencias y Artes de Barcelona.
Bassegoda Nonell, J. (1977). Bóvedas medievales a la romana. Separata Memorias de la Real Academia
de Ciencias y Artes de Barcelona. Tercera época núm. 782. Vol XLIII Núm. 8. Barcelona: Real
Academia de Ciencias y Artes de Barcelona. pp. 287-382.
Bassegoda Nonell, J. (1978). La cerámica popular en la arquitectura. Barcelona: E. Thor.
Bassegoda Nonell, J. (1989a). Construcción de bóvedas góticas catalanas. Bolletí de la Societat
Arqueològica Lul·liana. Revista d’Estudis Històrics. Any CV n 843 Tom XLV. Tercera Època.
Homentge a Gabriel Alomas Esteve, arquitecte. pp. 133-146.
Bassegoda Nonell, J. (1989b). La construcción de las bóvedas góticas catalanas. Boletín Académico.
Escola Técnica Superior de Arquitectura da Coruña, 1989, 11: 30-38.
Bofill, R. M. (1977). Un criteri just si no fos mancat. Objeccions catalanes a la Summa Catedralicia de
Sedlmayer. Lambard. Estudis d’art medienal Col. IX-1996, pp.39-49.
Borrego; Saranova. (1994). Envases cerámicos recuperados de las bóvedas de la Iglesia de Santa María
Alicante, importante enclave comercial mediterráneo en el bajo Medievo. LQNT 2, 1994, Alicante
pp.181-198.
Borromeo, C (1859) S. Caroli Borromaei. Instrucctionum fabricae et suppellectitis ecclesiasticae libri
duo. Editio revisa novisque adaucta. Tarraconae: Ex typographia Françisci Arís.
Bubnov. N.M. (1899). Gerberti postea Silvestri II papae opera mathematica (972-1003). Berlin:
Friedländer.
Carreras Candi, F. (1914). Les obres de la Catedral de Barcelona (1298-1445) (continuación). Boletín de
la Real Academia de Buenas Letras de Barcelona Vol. 50, pp. 128-136.
Domenge i Mesquida, J. (1999). L’obra de la seu. El procés de construcción de la catedral de Mallorca
en el tres-cents. Palma: Institut d’Estudis Baleàrics.
Ghyka, M. C. (1927). Esthétique des Proportions dans la Nature et dans les Arts. Paris: Librarie
Gallimard.
González, E. (1987). La cerámica bajomedieval de la Catedral de Mallorca. II Congreso de Arqueología
Medieval Española, Madrid. Tomo III, pp. 469-482.
Jiménez, Á. (2000). Rellenos cerámicos en las bóvedas de la Catedral de Sevilla. Actas del Tercer
Congreso Nacional de Historia de la Construcción, Sevilla, 26-28 octubre 2000, Madrid: I. Juan de
Herrera, pp. 561-567)
Lampérez, V. (1909). Historia de la arquitectura Cristiana Española en la Edad Media según el Estudio
de Los Elementos y los Monumentos. Vol. 2, Madrid: [s/n].
Lasteyrie, R. de (1926). L'Architecture Religieuse en France. A L'Epoque Gothique. Paris: Auguste
Picard.
Lluis i Ginovart, J. (2009, 753-761). La Scientia vero de ingeniis. El concepto de homogeneidad del
material versus resistencia en los pilares de una catedral gótica. Actas del Sexto Congreso Nacional
Historia de la Construcción. Valencia. 21-24 de octubre 2009. Madrid: Instituto Juan de Herrera.
Lluis; Almuni. (2011). La clave de la clau. El cierre constructivo del presbiterio gótico. Actas del Séptimo
Congreso Nacional Historia de la Construcción. Santiago de Compostela. 26-29 de octubre 2011.
Madrid: Instituto Juan de Herrera, pp. 753-761.
Lluis; Llorca. (2000). Pla Director Sancta Maria Dertosae. Tortosa: Bisbat de Tortosa. Departament
Cultura Generalitat de Catalunya.
Puig i Cadafalch, J (1921). El problema de la transformació de la catedral del nord importada a
Catalunya contribució a l’estudi de l’arquitectura gótica meridional. Separat Miscel·lània Prtas de la
Riba. Barcelona: Institut d’Estudis Catalans.
Sedlmayr, H. (1950). Die Entstehung der Kathedrale. Zúrich: Atlantis Verlag..
Street, G. E. (1865). The Gothic Architecture of Spain, with very beautiful drawings in his own hand.
London: John Murray, Albemarle Street.
Torres Balbás, L. (1939). Las teorías sobre la arquitectura gótica y las bóvedas de ojivas. Las Ciencias,
año IV, n 1, Madrid, 1939.
Torres Balbás, L. (1945). Función de nervios y ojivas en las bóvedas góticas. Investigación y Progreso,
Madrid, 1945.
Torres Balbás, L. (1946). Bóvedas romanas sobre arcos de resalto. Archivo Español de Arqueología, n
64.
Viollet-le-Duc, E. E. (1854-1868). Dictionnaire raisonné de l’architecture française du XIe au XVIe
siècle. Paris: B. Bance (A. Morel), 1854-1868, 10 vol.
Zaragozá, A. (2000). Arquitectura gótica valencia Siglos XIII-XV. Valencia: Generalitat Valenciana.
Conselleria e Cultura i Educació.
Zaragozá, A. (2008). A propósito de las bóvedas de crucería y otras bóvedas medievales. Anales de
Historia del Arte, Volumen Extraordinario 99-126.