Restoration / Architecture · Design and Construction
Guide · YOY Mimarlık
A glossary of restoration techniques
What the terms you meet in a restoration report or a board decision actually mean. From consolidation to anastylosis, from jacketing to patina — each term explained plainly, together with the situation it belongs to.
Intervention techniques
Consolidation. Strengthening a building’s material, structural system and ground in order to keep it standing. It is the lowest rung of the ladder of intervention, and from a conservation standpoint the best course is to stop here where possible.
Reintegration. Completing damaged or lost parts of a building or its elements, in traditional or modern materials, so as to restore the integrity of the original design. It is acceptable only when founded on real structural evidence or documents; reintegration proceeding from assumption and analogy is bound to be wrong. Giving the new part a different surface texture, so that it can be distinguished from the original, produces good results.
Renewal, re-use, adaptation to a new function (renovation, rehabilitation). Adapting a building that has lost its original function to a different one. Re-use is a means of saving old buildings from demolition — but it is a means: the plan or the ornament of the building should not be altered on its account.
Modern addition. Adding the new spaces that re-use requires — services, sanitary facilities, circulation. It is accepted only where no harm comes to the interesting parts of the building, its traditional setting, its composition, its balance or its relationship with its surroundings. When heavy programmes are imposed, the additions grow and the harmony of the massing is lost.
Reconstruction. Rebuilding a wholly destroyed or severely ruined monument or site on the basis of surviving records. Because the new structure possesses neither the original fabric nor the original material and workmanship, it carries no historical value of its own; it is therefore accepted only in exceptional cases.
Cleaning. Ridding a monument or urban site of additions that spoil its general effect and carry no historical or aesthetic value. Removing the valid contributions of different periods in the name of “unity of style” is not cleaning.
Relocation. Moving a monument to another position where conserving it where it stands has become impossible. Article 7 of the Venice Charter permits this only where the safeguarding of the monument demands it, or where interests of major national or international importance are involved.
Anastylosis. Re-erecting a collapsed ancient building by collecting and reassembling its own original pieces. Any additions used must be minimal and recognisable; where very little original material survives, it should not be attempted.
Consolidation techniques
Section widening and jacketing. Adding mass at the base of a leaning building or wall so as to enlarge the bearing area and bring the centre of gravity back within safe limits. Jacketing is the encasing of individual load-bearing members that have cracked or lost section and can no longer carry their vertical loads.
The rule of thirds. A rough method of assessing safety in buildings out of plumb: if a plumb line dropped from the centre of gravity falls within the middle third of the bearing area, the building is considered safe; if it falls outside the footprint of the wall, there is a serious risk of collapse.
Buttressing. Providing external support to resist the thrust of a wall or a curved roof. A solid buttress abuts the wall; a flying buttress works through a half-arch reaching from a detached pier to the main mass, and is preferred where there are details on the facade that should not be covered. Today temporary shoring is often used and removed once the structure has been consolidated.
Ringing, ties and anchor plates. Binding cracked vertical members with metal rings; tying opposing walls together with tension rods and tie bars. The vertical iron bars seen on facades are called kılıç in Turkish; they clamp the ends of the ties and point either to the original design or to a later consolidation.
Grout injection. Filling voids and cracks within the body of a wall with a suitable grout under controlled pressure, so as to recover the integrity of the masonry. The choice of material requires laboratory work; a mix incompatible with the original mortar makes the problem worse.
Other terms you will meet on site and in reports
Patina. The layer formed on the surface of stone over time, of both protective and aesthetic value. If it is mistaken for a dirt layer and scraped away it cannot be recovered; this is the commonest loss in careless facade cleaning.
Raspa (cutting back). The controlled removal of render or paint layers. It is done over limited areas to see the masonry beneath, the layers of decoration or the true state of a crack, and it requires permission.
In situ. Conserving an element where it stands. Protecting a floor or wall exposed in excavation by covering it rather than moving it is in-situ conservation.
Casting (mulaj). Taking a full-size mould of special details such as inscriptions and reliefs. Silicone rubber and latex are used; the result serves both as a record and, where needed, as a mould for producing a new piece.
Core sample. A cylindrical sample taken with a drill in order to identify the material. Because the method causes damage, it is used only where no loose piece can be found, and with prior permission from the conservation board.
Non-destructive evaluation (NDE). Investigation techniques that do not harm the building: radar and ultrasound to detect voids and differences of material within a wall; gamma radiography to locate metal fixings and assess their condition; endoscopy to see inside cracks. As a general rule these methods are preferred.
Stratigraphy. Reading the layers of fire, collapse and reoccupation on a site in their proper order. It is the fundamental method of the excavation survey; wholesale clearance of debris erases that order irreversibly.
Frequently Asked Questions
Which of these techniques will be applied to my building?
That is determined by the extent of the damage, not by preference. The rule is that intervention begins at the lowest rung and rises only so far as necessity can be demonstrated. The decision is taken element by element once the damage and decay mapping and the structural assessment are complete, and it is shown with a legend on the restoration sheet: which crack will be stitched, where grout will be injected, which surface cleaned, which section rebuilt.
My builder says “let’s do it the same as before”. Is that enough?
The intention is right, the method incomplete. Repairing a traditionally built structure with workmanship proper to its period genuinely matters, and a good craftsman is half of that. The other half is that the architect running the repair knows those techniques and materials, has studied buildings of the same period, and is equipped to supervise the craftsman’s work on site. In a registered building, moreover, no “same as before” carried out without an approved project is lawful.
If new additions must be recognisable, won’t the building look patched?
Being recognisable and being obtrusive are not the same thing. Where the contrast of colour and texture is exaggerated, the visual integrity of the architectural element is lost — there are well-known unhappy examples of this. The measure is this: a reintegration succeeds, in conservation and in aesthetic terms alike, when it helps the form to be read, does not obtrude at a general glance, and yet can be told apart with the naked eye at close range.
Source
The principal reference for these definitions is Zeynep Ahunbay, Tarihi Çevre Koruma ve Restorasyon (Historic Environment Conservation and Restoration), YEM Yayın, Istanbul 2009, Chapter 6: Restoration techniques. The principles cited rest on the relevant articles of the Venice Charter (1964).