Renovation and restoration Arthur Wolfrum, Christoph Dauberschmidt
C 5.1
About a third of all construction permits in Germany are issued not for new buildings, but for work on existing buildings. If you add to this the large number of building projects that do not require approval, the great impor tance of construction work on existing build ings now becomes clear. Projects involving buildings listed as protected, in which there is no alternative to working with existing build ings, make up only an insignificant number of such projects. Conversion is often less expensive than demolishing an existing building and building a completely new one. The growing consid eration of ecological criteria also makes the conversion of existing buildings attractive, especially in terms of their “grey energy”, i.e. the energy used to build a building. This con sideration becomes even more significant when a permanent concrete load-bearing or shell structure that has not yet reached the end of its “life cycle” still forms part of the building’s substance. As well as desired changes to a building, sim ple and ideally ongoing repair and mainte nance plays an increasingly important role in this context because it can help maintain a building’s value, which is of concern given the increased importance of real estate as a longterm investment.
C 5.1 Scuola Media, school, Locarno (I) 1963, Dolf Schnebli C 5.2 Common causes of damage showing frequent damage processes in buildings
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Although concrete has been a central building material for a long time, current renovations are particularly focusing on concrete buildings built in the 1960s and 1970s. Concrete struc tures built more recently are also being repaired, but increasing numbers of concrete buildings from this earlier period, which also saw a major building boom, are showing early signs of corrosion damage. In the 1970s in particular, concrete exposed to the weather was used more than it had been before. The large number of these buildings, as well as defects in the execution of their construc tion, is now making repairs and restoration necessary. Almost every part of a building can be built in concrete. The frequency, necessity, and
expense and effort involved in renovations may, however, vary greatly, even within the same structure. Mistakes made during con struction, a lack of careful maintenance and subsequent changes to structural elements often make renovation necessary. A still-intact concrete structure may have had to meet requirements when it was built that are different from those it is facing now, especially issues concerning sound insulation and fire safety, but also possibly involving higher standards of comfort. Building permits Renovations often have consequences for a building’s permit situation, which is not always obvious at first glance. Thorough research of these issues in advance is just as important for building regulation law aspects as it is for construction aspects. Before the consequences of new plans are assessed, the existing structure’s permit and approvals situation should first be examined. If the building’s owners are not able to pro vide building and planning permissions in text and plan, planners must request copies of these documents from the authority issu ing them. It often turns out that an existing structure diverges significantly from its building and planning permit, even before any new plan ning. This divergence must not necessarily be of a structural nature. On the contrary, one of the most common and serious divergences of reality from the approved building situation is the use of the building or parts of it in ways not necessarily indicated in the plans. Only knowledge of the existing building’s permit and approvals situation will enable a planner to determine whether a building regulation law procedure will be necessary before any technical measures can be taken. The range of regulatory requirements, whose breach would result in such a procedure, is too large to be exhaustively described here, but the main and, in practice, most frequently encountered issues include: