Structural Analysis of Historic Construction – D’Ayala & Fodde (eds)© 2008 Taylor & Francis Group, London, ISBN 978-0-415-46872-5

Intervention limits in floor wood structure restoration of a historicalbuilding

R.T.M. Ribeiro & M. HoirischPROARQ/FAU/UFRJ – Federal University of Rio de Janeiro, Rio de Janeiro, Brazil

ABSTRACT: In 1995, a routine inspection carried out by the Restoration Department of Federal Universityof Rio de Janeiro disclosed instability of wood floors in a room located in a Brazilian 19th century building.This paper presents a concise report of this structural degradation. It focuses mostly on the project of structuralrestoration of areas that brought about the practice works to be implemented in a historical building listed bythe Brazilian Historical Artistic Heritage Institute. Not limiting this study to a description of the strengtheningwork stages, this research analyses the actions adopted to restore the damage caused by termites in wood beams,trying to evaluate the adequacy in this specific work of the guidance of international charters of architecturalheritage. The main goal of this paper is to analyse the criteria that oriented the feasible restoration and the limitsof this intervention.

1 INTRODUCTION

The conservation criteria, available in charters, agree-ments and international declarations, are applied tothe restoration program of historical buildings. Oneof the most controversial matters by the conservationarchitects and heritage consultants’ standpoint is theinsertion of materials and constructive techniques inhistorical heritage.

The debate involving the replacement and/or inser-tion of degraded materials interplayed with the her-itage authenticity aspects and its values will herein bepresented.

In order to exemplify the technical issues, the casestudy of a wood floor restoration will be undertaken.The practice work has been performed in the city of Riode Janeiro, in a historical building, widely recognizedfor its artistic and cultural values.

This paper describes the structural restoration ofthose wood floorings. However, its main target isto demonstrate that the project here displayed hasrespected the intervention limits of restoration char-ters. In order to prove it, this study will show the reha-bilitation phases followed by the suitability betweenrestoration theories and practice.

2 THE ISSUE OF REPLACEMENT AND/ORINSERTION OF THE BUILDING NEWELEMENTS

By intervening in an ancient building, one must bearin mind its primary aim, in order to guarantee a proper

preservation: to value properly its original construc-tive elements. As a consequence, when dealing withthe restoration of the whole building or parts of it,materials should only be replaced and/or added ifthere is a technical requirement. The use viability ofthe architectural monument would be guaranteed, aswell as its preservation, preventing any imitation orcounterfeit.

The restoration project must start by the identifica-tion of the elements to be preserved and those suitablefor adaptation and/or removal. In order for this tobe accomplished, a precise and meticulous register ofthe building history is needed. Besides, the physicalstatus and its current conditions regarding construc-tive materials require special care when it comes topinpointing its frailties.

It must be underlined the need of a detailed surveyof new materials and technologies insertion, addingdistinct physical proprieties to the building, when com-pared to the existing ones. One must also analysethe utilisation of traditional materials and constructiontechniques in a historical heritage.

One of the resolutions of the Athens Conferencein 1931 was the use of modern techniques and mate-rials in consolidation work of historical buildings.However, the strengthening “should whenever possi-ble be concealed inasmuch as the aspect and characterof the restored monument may be preserved” (In:http://www.icomos.org).

The Venice Charter, dating from 1964 goes in thearticle 12: “Replacements of missing parts must inte-grate harmoniously with the whole, but at the sametime must be distinguishable from the original so

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that restoration does not falsify the artistic or his-toric evidence”. In addition to that, in the article 10:“Where traditional techniques prove inadequate, theconsolidation of a monument can be achieved by theuse of any modem technique for conservation andconstruction, the efficacy of which has been shownby scientific data and proved by experience” (In:http://www.icomos.org).

The Italian Charter of Restoration of 1972approaches a prevailing architectonic restoration stan-dard: “the replacement and possible integration ofornaments [. . .] ought to differ from the existing ele-ments, implying the material and surfaces to stand out,making them distinguishable from the originals”. Italso mentions the interventions must be implementedfor fear no doubt is left and by the most discrete manner(In: http://www.icomos.org).

The General Conference of UNESCO at Nairobiin 1976 recommends researches and systematic sur-veys on the use of modern techniques in conserva-tion works, as well as studies about craftsmanshiptechniques, important to the building safeguard.

3 THE MATTER OF AUTHENTICITY ININTERVENTION

The legitimacy of the restorative intervention in his-torical buildings was debated since the very beginningof restoration theories. Authors like Boito stated as afundamental concept the distinction of the new partsfrom the existing ones, as well as emphasizing the pru-dence of limiting intervention actions to the minimumrequired. All material to be added or replaced shouldhave a different feature, in the type of material to beused, or should bear a plaque, indicating the successivearchitectural alterations. The new parts to be insertedshould exhibit simple lines, being perfectly balancedwith the ancient building.

Later on, the Venice Charter has established that thenew elements ought to differ from the existing parts,and the same criterion was sustained by the ItalianCharter of Restoration.

This differentiation theory was strengthened in latercongresses, aiming at the visibility of the interven-tions to be carried out, refusing the idea of utilisationmaterial and techniques similar to the existing ones,preventing historical fraud.

In his book Theory of Restoration written in 1963,Brandi (2004) mentions the judgement of counterfeit.The author refers to the essential attributes the subjectshould possess, but is not able to earn: the falseness isin the judgement and not in the purpose. One of twoidentical objects may be considered a fake, accordingto its intention.

Pursuant to him, the distinction between copy, imi-tation and counterfeit is not in the specific diversity

of the production methods, but otherwise. Hereupon,he points out two situations in which an interventioncould be considered a counterfeit:

(1) Production of a purpose with the specific inten-tion of deceiving either the period, the materialcoherence or the author, or

(2) Diffusion of an object, not necessarily intendedto deceive as if it were an authentic work, fromthat period; by non-authentic authors and produc-ers different from the genuine one, and made outof distinct materials. In other words, it has beencreated with no counterfeit intention, but meant tobe divulged as the original.

According to Brandi, to get the counterfeit judge-ment, it is necessary to prove the swindle.

This issue has been developing, oftentimes beingdebated in international congresses and seminars. InJapan, November 1994, the Nara Conference, basedupon the Venice Charter, has discussed the authen-ticity issue linked to the intrinsic heritage value andthe cultural identity of the region in which it isplaced.

Following the international stream, Brazil hashosted the V Regional Meeting of ICOMOS in 1995.A regional document on authenticity of the southerncone countries was the result of this assembly. BrasiliaCharter established that authenticity of values is man-ifest, supported and preserved in the truthfulness ofthe heritage that we receive and transmit. Interven-tion must rescue building or site character, underliningits authenticity without transforming its essence andbalance, avoiding extraordinary actions and enhanc-ing its values. The Charter avows the quality of thetreatments as fundamental and all new elements intro-duced must be both reversible and harmonious with thewhole.

The issue of authenticity is rooted in the valuesattributed to the heritage. The judgement of valuewas broadly discussed in “The modern cult of mon-uments” by Riegl in 1903. This matter was the mainpoint of Nara Conference, in 1994, related to scientificstudies on cultural heritage, conservation and restora-tion planning and procedures for the World HeritageConvention.

The Nara Document claims that the authenticityemerges as the chief criterion when it comes to valuesattribution. “The understanding of authenticity plays afundamental role in all scientific studies of the culturalheritage, in conservation and restoration planning”.(http://www.international.icomos.org).

The interventions carried out in the UniversityPalace of UFRJ – Federal University of Rio de Janeirowill be herein analyzed based on these concepts, morespecifically the floor restoration of three rooms locatedin this building.

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Figure 1. University Palace. Photo: Soares, B., 2007.

4 THE EDIFICATION SUBJECT OFINTERVENTION

The University Palace (Fig. 1), heritage buildinglocated in the University Campus of Praia Vermelhahouses some faculties of Federal University of Rio deJaneiro. It is a neoclassical style building, situated inthe city of Rio de Janeiro, listed in Brazilian Historicand Artistic Heritage Institute.

The building exhibits restored rooms, ceilings andwalls smartly decorated, frequently used for concerts,congresses, academic, technical and administrativeactivities and solemnities. The rectory appointed theseareas to the academic community and to Rio de Janeiroinhabitants’ use.

4.1 Restoration of wood floors

The loose fixation between the beam and the clapboardof the floor in Education Faculty of Federal Universityof Rio de Janeiro lead to a prospective action in order tofind out its cause. The primary visual survey pointedto some clapboards disconnected, next to the walls.These supporting walls were wet. By analyzing theroof conservation status over these areas, it was pos-sible to detect clogging of the rainwater down pipe,leading to an overflow above the gutters, causing fre-quent infiltrations in the internal face of the wall andalso percolating its core, reaching the supporting clap-boards wood beams. This humidity has created idealconditions for the termite and fungus infestation in thefloor. Around 60% of the wood beams were infectedby termites. The micro-organisms and urban plagues,as we know, burgeon at humid zones, promoting therottenness of part of this beams, reducing partially ordrastically its original section (Fig. 2).

The Restoration Department was designated towork on a strengthening project of three wood floorrooms: (1) Science and Culture Forum coordinator

Figure 2. Assessment discloses a drastically reduced sectionof some beams. Photo: Hoirisch, M., 1995.

Figure 3. Location of interventions, DAMSTRUC (2005).

cabinet, (2) Coordination of Post-Graduation Programof Faculty of Education Coordination. (3) Goldenroom (Fig. 3). Under the supervision of the head archi-tect, a multidisciplinary team was gathered, composedby urban plagues biologists experts, structural engi-neers, and a proficient firm specialized in wood struc-tural restoration. The practice work evolved, therefore,in three lines. In the first one, biologists determinedthe termites infecting species, in order to guaranteethe efficiency of the plagues control program. In thesecond one, structural engineers calculate the remain-ing section of each wood beam, to make the structuralassessment. Finally, the practice restoration work wascarried out according to the engineers strengtheningproject.

The wood beams were properly inspected. For thispurpose, the clapboards of the rooms to be restoredwere removed after being mapped. The most vulnera-ble zones, located in the extremities and under the roofgutter called for extra care.The tongue and groove con-nections of the clapboards to the wood beams werepreviously done by means of long forged iron nails.They were then replaced by steel screws. This systemallowed the access to the beams, as long as from thattime on the wood beams assessment was to be made

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Figure 4. Fixation of floor beams in Science and CultureForum coordinator cabinet. Photo: Hoirisch, M., 1996.

Figure 5. Scheme showing replaced beams.

easier.The removal of the nails frequently destroys par-tially or completely the clapboards mortises, whilst theuse of screws allows their removal without damage,making possible the application of baits and productsto promote the termite and other wood degradationvectors.

The Figure 4 shows the ongoing floor restorationin the Science and Culture Forum coordinator cabinet,University Palace.

When defining the material to be adopted in thispractice restoration work, the wood seemed to bethe best choice. Studies pointed out which Brazilianspecies bore elasticity modulus fine enough to encom-pass the room wide extension. Special cares were takenso to guarantee the proper level of the new beams dry-ness. Stoves were used to assure its efficiency, whenreplacing and strengthening the pre-existing ones.

The Figure 5 shows a scheme of the replacedstrengthening beams in the Science and Culture Forum

Figure 6. Golden room after restoration. Photo: Soares, B.,2007.

coordinator cabinet.This proceeding has been likewisecarried out in the other two restored chambers.

Regarding the project of floors structural strength-ening, the Restoration Department had aimed in thefirst place at human’s life safeguard. Therefore, eachpre-existing structural wood beam has been assessed,to pinpoint those to be strengthened or replaced.Another special care was required from the biologistsresponsible for the termite control.The product used inthe disinfection process should not be toxic, to avoidharming the docents, students, employees and otherhaunters of the building, since the restoration practicehas been mostly achieved during academic year.

5 FLOOR RESTORATION SURVEY:INTERVENTION LIMITS

When opting for wood to be used in beams andclapboards replacing and strengthening, this was anatural choice, as the material embodies the conceptof the original project. However, the species werepicked out according to their elasticity moduli, notnecessarily taking into account the existing speciesfound in the room. However, wood benefiting wasachieved by modern extraction and sawing techniques.This proceeding abides restoration documents, like theVenice Charter and the Italian Charter of Restora-tion. This case study has respected the former: thereplacement and strengthening of the wood beamshas been integrated to the whole. However, concern-ing the intervention period, the difference betweenthe inserted material and those pre-existing onescan only be distinguished by the wood benefitingmodern system.

When it comes to the replacement of the iron forgednails by steel screws fixing the wood floors nextto the walls, the distinction between the pre-existingtechnique and the modern one is fully catered.

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The necessary strengthening in some of the tim-bers was accomplished by the “sandwich” technique,putting two new pieces parallel to the pre-existingones.

The remaining doubt refers to the highly perishablefeature of the wood, mainly when utilized in humidtropical weather (Rio de Janeiro relative humidity isabove 70% all year round). If this high humidity levelfoments the termite infestation why had not the tim-bers been replaced by a more long lasting material,like steel?

The option for metallic beams could pinpoint theexact intervention period, and the advices of the her-itage charters would be abided. A future survey couldallow the identification of steel utilization as datingfrom our times. An extra benefit would consist of theprolongation of the inserted beam durability, whencompared to the pre-existing one. By the way, oneof the main goals in restorative interventions is tohinder new interventions on a short span. The replace-ment of wood beams by metallic ones could be threata future, for the utilization of modern materials andtechniques would make a “patchwork” out of theheritage building. Losing the constructive original fea-tures dated from its erection period would mean losingits authenticity as well.

Concerning its physical aspect, a primary mappingof the pre-existing wood pieces had been performed,before the removal of the floor wood clapboards,allowing its fixation to the previous position. The newinserted wood pieces followed the original pattern, theusual proceeding in these cases.

6 CONCLUSION

The current theories tell the insertions from the whole,and were applied to this restoration work. The mate-rial had not been changed, likewise preserving theauthenticity of the building. Moreover, the durabilityof the restoration practice carried out may disagreewith future conservation decisions.

The key point about the restoration proceedings def-inition and the materials to be utilized depends uponthe limits of the intervention; in other words, up towhat extent is it possible to intervene in a heritage?

This intervention ought to be limited by the preser-vation of a historical building, its values, authenticityand identity of the local cultural heritage where themonument belongs. One must dedicate special careto the values to be preserved and what would be theessence of restoration practice.

Regarding our heritage actions, this is a conceptand paradigm changing era. The target should not onlybe the material safeguarding, but mainly the historicalbuilding image and authenticity, as a cultural identityoffspring.

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