There are many reasons why the definition of these terms is so vague. Firstly, the level of conversion work varies greatly when measured against the extent of the existing building that needs to be retained; it can range from small-scale repairs through to essential structural restoration. There are also different motivations for changing the structure of a building: aesthetic, practical or user-specific. Added to this is a “traditionally” vague choice of words which makes it impossible to assign explicit, clearly defined terms to the different types of building work. Nevertheless, this overview will attempt to summarise and delineate the different terms. This is not in order to provide conclusive definitions. The aim is rather to give architects a handy index to help them in their planning. Different types of work on an existing building require both different planning methods and different kinds of construction. If the architect is able to give a name to their task, it will help them to clarify the planning and building process. Hence the following terms will not only be explained and defined, there will also be practical advice for implementing the planning task.
Renovation – what’s what? Terms and their definitions
There is no all-encompassing, universal term to describe all of the building work that is carried out on existing buildings and which is also generally understood as such. In addition to the term “renovation”, there is a range of words which have similar or sometimes identical meanings: conversion, maintenance, modernisation, dismantling, redevelopment, restoration, and upgrading. Georg Giebeler, University of Wuppertal (Germany), gives us an overview.
The terms have been assigned from two standpoints: firstly according to the extent of the work that needs to be carried out on the existing building, and secondly according to the scale of the new building work. Planning methods and construction tasks can be derived from a combination of the two. The scale of the work ranges from the reproduction of a building that either no longer exists or only exists in parts, complete demolition and rebuilding, through to varying degrees of preservation (renovation to gutting). Added to this are more terms which can be linked to renovation: modernisation, removal of dangerous substances, extensions / annexes, development and change of use. In many cases, several terms refer to one building task because they overlap in places or where several types of work are carried out at the same time. Let’s take the terms “ongoing construction” and “redevelopment” by way of categorisation. Neither of these describes a technical process; rather they concern an attitude. Ongoing construction reflects the continuing process of building: it’s an open-ended cycle. It also implies that each step needs to take account of the existing structures. Therefore it’s not really “redevelopment”, but “development of existing structures”.
Reconstruction is understood to be the reproduction of a building that no longer exists; strictly speaking, it is really a newbuild. Genuine reconstruction, however, relies on old building constructions. Reconstructions are always a controversial topic. Criticism is generally fiercer where less is actually reconstructed, i.e. faithfully restored. The plans for the Berlin Palace, for example, were heavily criticised, while the reconstruction of the Frauenkirche in Dresden was met with great approval. Although they are based on old designs, reconstructions are always newbuilds with no original building. Generally, the familiar rules for newbuilds therefore apply: standards and laws, manufacturer guidelines, building processes, construction time, the type of specification and the site management. The work methods during the planning stage are also similar, as historical buildings are seldom sufficiently documented such that the architect doesn’t need to design something new. Additionally, the Second World War saw the destruction of a large proportion of the European (and especially German) building archive, which means that you often need to rely on illustrations or photographs rather than scaled architect plans. In addition to reworking the existing sources for the original building, reconstruction as a concept is also an artistic imitation of the construction style of a certain era by the current architect. This means that it is not an exclusively scientific task. Contemporary specialist literature helps during the planning stages when it comes to recreating old constructions as true to detail as possible using modern tools.
Restoration is the completion of an unfinished building. The term comes from the period of Romanticism, when interest in cultural monuments of the past became the focus of attention. This was essentially embodied by French architect and cultural historian Eugène Viollet-le-Duc, who restored a number of medieval castles at the beginning of the 19th Century. Cologne Cathedral was completed after nearly 300 years of construction standstill. Restoration is very similar to reconstruction. The only difference is that, in the case of the former, original building parts still exist and are added to so that they match the style of the era. The similarity of restoration to reconstruction likewise makes it controversial: “The process of restoration is a highly specialized operation. Its aim is to preserve and reveal the aesthetic and historic value of the monument and is based on respect for original material and authentic documents. It must stop at the point where conjecture begins,” (Venice Charter, 1964). However, this well-meaning piece of advice is often ignored, and often because original documents are not available to rely on. It is also not always clear what is deemed to be the original: the first building, the first extension, the first renovation or the first conversion? This conflict runs through the expert debates of the last decade, and the answers are more of a reflection of the respective Zeitgeist rather than being generally accepted. This is possibly also due to the fact that the term “original” was incorrectly carried over from visual art to architecture, which has never known of this term.
Around the turn of the century, urban planners took the topic of demolition as “negative building” and revamped it as “conceptual demolition”. The catalyst for this was the copious number of empty homes in East German cities following reunification. But there are comparable problems in other regions too. They are usually a result of deep-rooted, structural processes which trigger an economic decline and thereby a mass exodus of residents – such as in Detroit after the collapse of automobile production. The intention of demolition is to heal urban problems of empty homes by specifically demolishing individual buildings, blocks or city districts and therefore control the shrinking process. However, these concepts often fail due to a lack of financing, as demolition without a newbuild never yields returns
In addition to large-scale demolition, individual buildings are often demolished to make way for a newbuild in their place. This is not a service provided directly by the architect, because it is often carried out by specialist companies during one stage of the project development, as only they have the corresponding specialist knowledge. In addition to building regulations (demolition approval), structural properties (specific demolition structural properties) and safety guidelines for the workforce and residents as well as environmental protection measures for harmful and hazardous materials all need to be observed.
Upgrading / maintenance
Upgrading does not add anything new to the existing building or replace the old with the new, but rather preserves the value and function of the existing building through professional “maintenance”. Rental properties are typically upgraded in this way. The German Second Calculation Regulation (Zweite Berechnungsverordnung) stipulates in this regard: “Cosmetic repairs only include wallpapering, painting or whitewashing of walls and ceilings, painting of floors, radiators including heating pipes, internal doors as well as the inside of windows and external doors”, (Second Calculation Regulation, section 28). The legislation also deems maintenance a the following: “Maintenance costs are those costs which must be expended during the period of use to maintain the intended use, in order to properly remed any structural or other defects due to wear, ageing and weather exposure.” The legislation includes work which actually falls under maintenance: “Minor maintenance work includes exclusively the repair of minor damage to installations for electricity, water and gas, heating and cooking appliances, window and door locks as well as the closing mechanisms of window shutters.” “Failure to carry out maintenance work may lead to greater damage in areas that are not visible, such as flat roofs.” Developers should therefore provide the client with a summary of appropriate maintenance work including routine intervals and work instructions – an additional service to be provided in accordance with the fee scale for architects and engineers (HOAI).
Repair / servicing
Servicing is limited to the replacement or repair of defective building components. Servicing work takes place regularly between the overall renovation interval and usually falls to the property management without planning support. For reasons of economy, you should monitor how frequently the servicing of the same components is carried out. For example, a burst water pipe can happen at random, but is not something that occurs every year. If it does occur every year, it is advisable to replace all of the water pipes from the basement up. However, burst pipes can be fixed through earlier servicing if, for example, copper pipes are added to an iron pipe system. Servicing work inevitably leads to follow-up costs which can significantly exceed the actual repair costs – such as when intact floor tiles need to be pulled up in order to find a burst pipe. This raises the question of whether it makes sense to take the opportunity to renovate the entire bathroom at the same time.
Partial renovations focus on just one part of the building, such as the façade, the ground floor or the east wing. They are one of the most difficult jobs to arrange, as they are carried out while the building is still in use. There is sure to be conflict with the users, as partial renovation work cannot be carried out separately; the technical infrastructure stretches across the entire building, for example. An effective strategy is to give detailed advance notice of the planned activity. Mortise work in inhabited buildings, for example, is very annoying, particularly when it starts at 7 o’clock in the morning. Consideration of contractually agreed work times as well as communication of the building work period both help to remedy this. The work remains annoying, but the time limits increase acceptance. A similar case applies to putting up scaffolding, decommissioning infrastructure (particularly the television), work on internal and external access points as well as all work which involves an above average level o dust, noise or vibration. With partial renovations in particular, the time and cost buffer should be set higher than usual and a budget should be in place for collateral damage to parts that aren’t actually to be renovated. This damage is unavoidable and its rectification should be unbureaucratic and fast. In addition, the client should be advised straightaway of the risk of lost rent in the case of let buildings. After all, if the “suitability of the rental property for use as stipulated in the contract” is negated or decreased, German jurisdiction states that the rent can be reduced by an average of 20 %. This is already the case if the residence cannot be ventilated following the build-up of dust or if it is not possible to use the telephone in an office because of the noise.
Complete refurbishment / general refurbishment
Dismantling work in the case of general refurbishment is very extensive. It reduces the building almost to a shell. The primary construction remains unchanged for the most part. Typical work includes complete replacement of the infrastructure as well as retrofitting of all building components in line with today’s laws and standards. Due to its extent, general refurbishment work is very costly, particularly if additional work is required to remove harmful substances. In return, however, you get a building which comes very close to a newbuild in terms of facilities and safety. This is also reflected in the fact that upon completion virtually all components have a warranty, including in terms of current standards and laws. In the case of simple renovations, this is often not guaranteed, or is only guaranteed to a certain extent, as many components remain in their original condition. In terms of planning, general refurbishment does not differ fundamentally from a newbuild, seeing as many uncertainties are almost cancelled out. From an economical viewpoint, weaknesses from the building shell that cannot be remedied may remain, such as missing horizontal damp-proof barriers, excessive ceiling deformations or sound insulation weaknesses due to low surface weight. The evenness tolerances, which usually fall outside the current standards (which have only been regulated since 1969 by DIN 18202, Sheet 1) must also be taken into account during planning.
In contrast to servicing, renovation work includes intact, but perhaps outdated, building components and surfaces. Unlike with conversions, however, they do not involve any significant changes to the load-bearing structure and room layout. They therefore lie precisely between servicing and conversion. The extent of renovation work can vary widely.
Standard renovations cover the entire building or at least an autonomous part of the existing building that is clearly marked off. The necessary dismantling work usually extends to just surfaces or preliminary work for the retrofitting of fire protection, sound reduction or thermal insulation. Additions and changes to the existing infrastructure are common, but it is rare that it is completely replaced. Renovation cycles for individual building components are relatively easy to determine empirically. Proper renovations without changes of use do not require any building regulation approval and are covered by the building insurance, while this usually ceases in the case of general refurbishments or conversions.
Gutting / newbuild with partial preservation
Gutting is very similar to a newbuild. It often involves work – resulting from a disputed understanding of monument conservation – where the façade of an old building is kept while the interior is completely gutted and rebuilt
Conversions always change the structure of the building. They expand on the term “renovation” to include intervention in the statics and/or room arrangement. With conversions, it is therefore essential that you deal with the existing load-bearing structure. Fundamental renovation work is almost always a conversion, such that many types of building work can be best described by several terms, for example “general renovation with conversion”. Structural work requires structural verification, which must also include the existing building. This means that it is essential to carry out early and often disruptive checks of building materials used and construction processes, for example, prising open a concrete ceiling to clarify the type and location of the reinforcement. Professional design services are also required for conversion work, as they can be used to make changes to the arrangement of rooms or access points. This additional planning work is taken into account as a conversion surcharge in the German fee scale for architects and engineers (HOAI). Partial conversions can be considered in the same way as partial renovations.
Prof. Georg Giebeler holds the professorship for “Development of existing structures and construction” at the University of Wuppertal. He completed his degree in Architecture at TU Graz. He has been running architectural practice 4000architekten in Cologne since 1995. Following a teaching position in Darmstadt in 2002-2003, he received his first professorship for construction at the University of Wismar and the professorship for “Designing and developing existing buildings” at the RheinMain University of Applied Sciences in Wiesbaden.