Existing and Historic buildings Research Papers

Structural models of critical regions in old-type rc frames with smooth rebars

2004, Engineering Structures

Structural assessment of existing reinforced concrete constructions under gravity loads and seismic actions has a high social and economical impact; actually in many European countries, most of the buildings dates back to 1960s and 1970s... more

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Masonry infill construction and retrofit technique for the infill-frame interaction mitigation: Test results

by V. Bolis and

The paper describes the set-up and testing of an innovative construction technique for masonry infill, which can provide a flexible and predictable in-plane response to the infill inside the frame, together with a stable and reliable... more

he columns in 3 points and their static scheme differs from that of the central ones, as shown in Figure 1

behave as sliding joints during the in plane deformation and ensure the out-of-plane stability of the infill.

with continuous “shear keys” (Figure 4b), which were embedded in the masonry mortar during the infill

frame beams (Figure 5 5c and 5d). Such connection was obtained by first dowelling a “U” shaped steel
) by means of a saw and the successive integration of the vertical elements and their connection to the
gaps between the masonry sub-panels and the planks restored the continuity of the infill. Figure 6b shows
[he insertion of the planks in the wall required the execution of vertical cuts in the infill (Figures 5a and
he vertical planks detailing. Pairs of “L” shaped steel profiles were screwed on both sides of the planks, in
order to optimize the depth of the masonry out-of-plane arching and serve as a mold for the subsequent
kg/m?. The blocks were laid in running bond, with the holes in horizontal direction, on layers of a weaker

ide of the wall, simulating the intervention from outside the building to limit the building downtime.

After the in-plane test, the specimen was tested out of plane, in order to evaluate its stability in presence of
specimen inter-storey drift, the load applied by the jack, the relative sub-panels vertical sliding and theit

respectively. In Phase 1, the specimen highlighted a ductile cyclic behavior with negligible damage,

limited damage at the end of the test Phase 1.

the infill, most probably thanks to the activation of the vertical arching mechanism spanning in between the
4,2. Specimen B
93KN applied, and no significant stiffness degradation was observed up to the maximum load of 102kN

contribution of the rocking mechanism is lower than 1kN. However, in this case the infill reaction was
column and the adjacent vertical planks. Such gap was monitored during the test and its partial closure was

The performance of the prototype infill built with vertical sliding joints is compared in Figure 14 with those

In the first part of the test, a 4cm gap was left between the masonry sub-panels and the upper beam; while
M5 resistance class lime-cement mortar bed and cross joints (15mm thick). Table 1 reports the materials’
dimensions 250x200x190mm (LxTxH), characterized by a 50% voids ratio and a density of 810 kg/m°, and
To protect the masonry from local crushing after the filling of the gap, wooden boards were placed

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Embodied Energy Policies to Reuse Existing Buildings

by Pere Fuertes

2017, Energy Procedia 115

When dealing with the existing stock of buildings, energy strategies usually focus on the improvement of their performance by means of technical upgrading. However, taking architecture as a resource helps to raise another question: to... more

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ANALYSIS OF THE INFORMATION NEEDS FOR EXISTING BUILDINGS FOR INTEGRATION IN MODERN BIM-BASED BUILDING INFORMATION MANAGEMENT

by Bjørn Arild Godager

The challenge is to decide how to design a building information model (BIM) to support building maintenance and development for existing buildings. Until now the main BIM focus has been related to new projects, and this study focus on... more

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Nabataean Architectural Identity and its Impact on Contemporary Architecture in Jordan

by Shaher Rababeh

This paper draws attention to the crucial problem of how to approach to design issues based on cultural identity within a global world, by referring to Petra and Nabataean architecture. This issue is related to the Nabataean architectural... more

Fig. 1. Mabataean Kingdom, its extent, arnctent trade routes and major centres, Petra and Medain Saleh (After Rababeh, 2005: Fig 1.15)

Fig.2. Crowstep motifs; the most widespread geometrical form noted on the tomb facades. With rows of crowsteps on the left and half crowsteps in the right.

Fig.3. Crowstep (as two halves) and the cavetto cornice motifs.

Fig.9. The traces of chiselled lines tilted at 35 to 55 degrees to the horizontal are the most common feature resulting from Nabataean sandstone dressing.

Fig.4. The large and richly decorated facade of El-Khazneh, complicated and showing stronger classical influences, Petra.

Fig.5. The large and richly decorated facade of ed-Deir shows a combination of classical and oriental styles, Petra.

Fig.6. The Obelisk tomb with the upper storey distinguished by its visual character of the four obelisks

Fig. 7. A Nabataean capital, the Blue Church.

Fig.10. The crowstep split into two halves on the facade of Al-Hussein Bin Talal University.

Fig.11. The main gate of Al-Hussein Bin Talal University using the split crowstep, rose red colour, and the broken pediment images

Fig.12. Agrey granite urn supported by a Nabataean capital as a land mark of Nabataean heritage in the middle of the circle of Al- Hussein Bin Talal University.

Fig.13. Half Crowstepsused as shelves for artefacts behind the main counter of the restaurant, Crown Plaza Resortin Wadi Musa

Fig.14. Al-Jamal student accommodation, Irbid, designed by the author, used the row of crowsteps, and the tholos on the mair fagade.

Fig.15. Abu-Alrob residential building in Irbid, designed by the author, shows the use of a sloping broken mass, which portrays the broken pediment, and the massin the centre with triangular cross-section reflects the image of the tholos.

Fig.16. Villain Mafraq, north Jordan, the whole of the centre part of the composition is copied from el-Khazneh.

Fig. 17 Exterior view of facade The crowstep motif was functioned to indicate the main entrance by showing integration of mud brick into concrete frame of the left side of the main entrance fagade showing integration of mud brick into concrete frame, King Abdul Aziz Foundation for Research and Archives, Riyadh, Saudi Arabia (Badran, 2008).

Table 1 The most significant basic vocabulary that symbolises the Nabataean architecture contains the following characteristics or codes.

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Building 'Post-Growth': Quantifying and Characterizing Resources in the Building Stock (Doctoral Dissertation)

by Satu Huuhka

Tampere University of Technology. Publication 1414.

Building stocks will play growing roles in the extraction of secondary construction materials in future. Moreover, as there is a need to decouple buildings’ service provision from their material consumption, building stocks should, in... more

Building stocks will play growing roles in the extraction of secondary construction materials in future. Moreover, as there is a need to decouple buildings’ service provision from their material consumption, building stocks should, in fact, be considered not only as deposits of raw materials but also as reserves of space. Despite of their significance, these stocks tend neither to be well known nor systematically analysed. The end-of-life phase of buildings is especially poorly covered in research, although the aspects of buildings’ mortality and survival are fundamentally intertwined. The omission is highly problematic, because it precludes understanding the fundamental dynamics of the stock.

The current study is situated in Finland, where the basic composition of the stock is relatively well established in the Building and Dwelling Register, contrary to many other countries. Taking advantage of statistical description, this dissertation explores the geography and characteristics of obsolete parts of the Finnish building stock, that is, demolished and problematically vacant buildings. The dynamics, or the relations, within the stock are also considered on a very basic level, with the help of a simple correlation analysis. In order to exemplify refining the results of this kind of top-down research, the study then switches to a bottom-up approach and zooms into the more specific composition of a selected age-use cohort, the 1960–80s blocks of flats. The types and dimensions of the cohort’s components, or concrete panels, are inventoried, and the results are compared to the current requirements for dimensioning living spaces. Furthermore, the spatial configurations of flats, the service provided by these physical structures, are also investigated using graph theory informed typological methodology. The findings consist of a typology of flats characteristic to the cohort. Lastly, the extents of the reserves in the entire stock of demolished buildings, the stock of problematically vacant residential buildings and the exemplary cohort (its existing, vacant and demolished parts) are quantified and proportioned to each other and new construction, inter alia.

By highlighting the magnitudes of secondary deposits of materials, components and spaces, this dissertation suggests that public policy should start paying more attention to the building stock and the potentials embedded within it. Even though an unambiguous relation between vacancy and demolition was not identified, the key finding from the resource perspective is that significant amounts of obsolete buildings are geographically concentrated on cities. In order to practice sustainable policies on the building stock, planners and decision-makers should be better aware of these reserves and acknowledge their adaptation and modification capacities.

Figure 1. The waste hierarchy of the Waste Framework Directive (EU, 2008: 10), applied to the context of buildings and building stocks Alarmingly with regard to these targets, policies have been deemed to favour demolition and new construction over life cycle extension (Hassler, 2009; Thomsen & van der Flier, 2011). With a more than 50% proportion of all extracted raw materials (EC, 2011) and a 25-30% share of all waste (EC, 2016), construction is already amongst the most environmentally burdening fields of industry in the European Union (EU). Thus, in 2008 EU issued a Waste Framework Directive that specifies a hierarchy (Figure 1) for future waste policies (EU, 2008: 10). The hierarchy's first three levels conform to the needs of the new 'post-growth' economy. This denotes that in future, resources should not be primarily extracted from the geo-ecosphere but from the anthroposphere: in case of buildings, the existing stocks. Industrial by-products have been recycled for long now, but these secondary flows are decreasing due to the increased efficiency of industrial processes. Moreover, the aims are now to shift from material recycling to the reuse of ready-made products. Avoiding the replacement of buildings in the first place should be increased, meaning that buildings should take up new uses. Building stocks should, hence, be considered as reserves for present and upcoming needs (Kohler & Hassler, 2002), and the evaluation of their value should not base on their current performance but the potential they withhold (Thomsen & van der Flier, 2011). Because the current economic system exacerbates the use of short- sighted management strategies, policies should be aimed at preserving the physical and cultural capital embedded in the building stock across generations. There is a need to find new tools for this work, because the limits of traditional conservation strategies are rather obvious in the context of entire stocks. (Hassler, 2009). are rather obvious in the context of entire stocks. (Hassler, 2009).

Figure 2. Conceptualization of the composition of the building stock and the relations between different parts thereof.

Figure 3. Distribution of value of Finnish building construction in 2014 (adapted from Rakennusteollisuus, 2015a). RB=residential buildings, NRB=non-residential buildings. Kohler and Hassler (2002) argue that building stocks have not been analyzed systematically in the past, but because the amount of renovation activities has already surpassed or will soon surpass that of new construction, a paradigm shift is now inevitable. The remark is applicable to Finland as well: as seen in Figure 3, the Finnish renovation market was slightly larger than the new construction market in 2014 (Rakennusteollisuus, 2015a). Unlike in new construction, in renovation the market is larger amongst residential buildings (RB) than non-residential buildings (NRB). larger amongst residential buildings (RB) than non-residential buildings (NRB).

Figure 5. Conceptualization of the development of Finnish housing during the 21° century: annual new construction in urban and rural settings; urban (quarter) structure; architectural styles; project characteristics; technical solutions and_ societal developments juxtaposed with each other. (Adapted from Kahri, 1979: 42; supplemented with information from Hyt6nen & Seppanen, 2009: 301; Kakko, 2011: 120-1 and Neuvonen, 2002: 10-1). Note: Classifying communities into urban and rural has ceased due to many small municipalities adopting the title of a ‘city' during the 1970s (personal communication, K. Degerstedt / Statistics Finland, 5.4.2016). The Finnish stock is notably young compared to most European countries (Hassler 2009; Meijer, Itard & Sunikka-Blank, 2009). This is because Finland industrialized anc urbanized relatively late; year 1957 is sometimes mentioned as a kind of watershec between more ‘traditional’ and modern construction (e.g. Siikanen, 2008: 17 Kammonen, 2012: 50). In all, 70% of all buildings and 80% of floor area have beer erected after the 1950s (Statistics Finland, 2015). Figure 4 shows that the peal decades in terms of floor area are the 1970s and the 1980s, with around one-fifth of the stock built on each of these decades. This, however, also depends on the building type For instance, the number of detached houses was increased in an unprecedentec manner already during the post-war resettlement of evacuees from ceded areas Blocks of flats, then again, started to increase significantly as late as in the 1960s. Blocks of flats, then again, started to increase significantly as late as in the 1960s.

onwards. Also public buildings, commercial and office buildings and utility buildings are

Figure 14. Vacancy rates and demolition rates in Finnish municipalities

Figure 15. Numbers of demolished homes with different building and tenure types. * Other tenure types include right of occupancy and unknown tenure. ** Other buildings include NRB and unknown building types.

Figure 8. Construction materials and methods of demolished buildings and residential buildings with problematic vacancies. (Article |; raw data of Article I; Article II). When the issue of construction material is approached through floor area, the results are similar in the order of magnitude irrespective of which part of the obsolete stock is looked at (the demolished part or the problematically vacant part of RB). Amongst demolished stock, the share of timber is 41% and the share of concrete 35%, and

Figure 14. Typical flats in 1960-—80s apartment blocks (Article IV).

Figure 15. Prevalence of flat types in slab blocks (Article IV).

Figure 16. Prevalence of flat types in tower blocks (Article IV).

Figure 18. Floor areas of demolished buildings in all building classification categories (Appendix |), 76 building types in total, plus buildings whose type is unknown. Note: Colour code follows that of Figure 4 with the exceptions that Figure 4 omits free-time residential buildings (turquoise), firefighting and rescue service buildings (grey), agricultural buildings (brown) and unknown buildings (navy). (Raw data of Article !).

Figure 19. Extents of municipalities’ reserves of problematically vacant homes in different building types in comparison to annually newly constructed floor area (average from 2000-12). (Raw data of Article |; Raw data of Article II). Note: The problematically vacant floor area used in this calculation covers only the area of vacant homes in buildings with problematic vacancies, whereas the area of new construction contains the corridors and other common facilities. Therefore, the compared data are not perfectly commensurable, and the results are approximate houses and 154 times for blocks of flats. This is to say that at the current pace, it woulc take more than a century to demolish the long-term vacant homes. In terms of floo area, the proportion of multi-family buildings with problematic vacancies appears more significant than if only vacant homes are observed. Their extents are, in a respective order (detached houses - row houses - blocks of flats) 8, 16 and 12 times the annua production and 132, 469 and 246 times the yearly demolition of floor area. The reade should, however, remember that even the problematically vacant multi-family building: also contain many occupied homes. (Article Il). Figure 19 elaborates on the relation o annually newly constructed and problematically vacant floor area of different RB type: on the municipal level.

Figure 1. Shares of demolition in growing, shrinking and steady-state municipalities In terms of the number of inhabitants, the majority of communities have been in transition during the examination period: 30% have grown, 60% have been shrunk and only 10% have remained stable. As Figure 1 shows, the group of growing communities host the majority of demolition. The average area of buildings demolished in growing municipalities is also on average 36% larger than in steady-state communities and 53% larger than in shrinking communities. municipalities is also on average 36% larger than in steady-state communities and 53% Figure 2 shows that the capital region and urban municipalities are together accountable for most of demolition. In addition, the table demonstrates that the more urban the municipality, the larger the average area of the demolished buildings. As seen in Figure 3, the more urbanized the part of town, the more demolition takes place and the larger the demolished buildings are on average. In the cities, the average area is more than double than in the countryside. With this indicator, rural towns-are very close to cities.

Figure 4. Shares of count and area of all buildings by age at the time of demolition

Figure 6. Shares of count and area of NRB by age at the time of demolition

Figure 1. Map of Finnish municipalities. Base map Finnish Land Survey.

Figure 2. Gross vacancy rates and populations of Finnish municipalities. Note: The figure has been cropped to exclude nine cities with over 100 000 inhabitants for better readability.

Figure 3. Vacancy rates for different tenure types and populations of Finnish municipalities: a) owner-occupied housing; b) private rental housing; c) public rental housing d) other (right of occupancy and unknown). Notes: In the whole housing stocks of municipalities, the shares of the tenure types are as follows (average [min, max]): owner-occupied 73% [46; 90]; private rental 13% [5; 44]; public rental 8% [1; 20]; other 6% [3; 20]. The figure has been cropped to exclude nine cities with over 100 000 inhabitants for better readability. Clearly erroneous figures (i.e. 0% and 100%) have been removed from the figure. These include public housing in Aland Islands (16 municipalities) due to data missing from the official statistics.

Figure 5. Building year distribution of detached houses. Buildings with problematic vacancy Buildings with normal vacancy OFully occupied buildings

Iblematic vacancy WBuildings with normal vacancy OFully occupied buildings Figure 6. Building year distribution of row houses.

Figure 13. Vacancy rates and numbers of demolished homes in Finnish municipalities.

In the end of the 1960s, the concrete industry launched a research project that aimed at the creation of one open standardized panel technology (Figure 2) called the BES (abbreviation of 'betonielementtistandardi’, Finnish for 'concrete panel standard’). The main aim was to allow purchasing different elements, such as exterior walls, interior walls, slabs, balconies and stairs from different producers. (BES, 1969). The study, based on benchmarking a remarkable amount of panel systems in other countries, was completed in 1969 (BES, 1969). The first BES blocks of flats were inaugurated in 1971 (Hyt6nen & Seppanen, 2009, p. 107) and BES superseded the factory-specific systems during the 1970s. The most notable difference to previous systems was replacing solid concrete slabs with hollow-core slabs, similar to those used in Germany and Canada (Hyt6nen & Seppanen, 2009, p. 50, 104). Swedish-developed Nilcon or U-slabs, which represent prefabricated versions of upstand beams with integrated decks, were also used, but they were in the minority due to multiple weaknesses in comparison to hollow-core slabs (Hyt6nen & Seppanen, 2009, p. 106). These pre-tensioned slab types enabled longer spans and reduced the amount of load-bearing interior walls main aim was to allow purchasing different elements, such as exterior walls, interior

2.2 Connections, deconstruction and re-connection

Figure 4. A steel loop connection (left) and a steel hook connection (right). (Redrawn from BES-suositus, 1972). costs is equivalent to savings achieved in Germany (Huuhka et al., 2015). As for the deconstruction of the typical connections, the Finnish experience is twofold. Deconstruction of blocks of flats was first experimented with in 2000, but it was found too laborious to be financially attractive for construction companies (Kauranen, 2001, p. 31-33, 38). Although reuse was neither planned nor attempted, the report concludes that the lack of applications is a barrier for reuse. The second effort took place in 2008— 2010 during a neighborhood rehabilitation project in Raahe. In this case, deconstruction and small-scale reuse (Figure 5) were carried out successfully and resulted in savings in the construction costs. (Huuhka, 2010b). The 36% reduction of costs is equivalent to savings achieved in Germany (Huuhka et al., 2015).

Saastamoinen (2013, p. 101) estimates that original rebars and connection steels car be used for reconnection of old panels if the grouted joints are chiseled open carefully without cutting the steel bars. Another option is to use a diamond saw, but that may shorten the element and cut the rebars (Saastamoinen, 2013, p. 106-108). If the rebars are cut, new connection steel bars must be grouted to the edges of panels before grouting the panels together again. Non-load-bearing facade panels suspendec from the ends of bearing interior walls are the easiest to reconnect (Saastamoinen. 2013, p. 99). According to Makio et al. (1994, p. 78, 98-99, 133-134), this was the most common joint type used in Helsinki. However, according Saastamoinen (2013, p 35), this technique was in the minority in the city of Tampere. A steel hook connectior between load-bearing panels (Figure 4, right) is easier to chisel clean than a steel loor connection (Figure 4, left). The former seems to have been the most usual joint type ir Tampere (Saastamoinen, 2013, p. 35) and it was also encountered in the Raahe deconstruction project. Makid et al. (1994) do not report which was more common ir before grouting the panels together again. Non-load-bearing facade panels suspended

Figure 6. The distribution of protective pore ratio in different surface finishings of concrete facades (Lahdensivu, 2012). In Finland, concrete is considered to be fully frost-resistant if the material has a protective pore ratio of 0.2 and completely non-frost-resistant if the ratio is below 0.10. In 70% of existing concrete facades, this ratio is less than 0.15. The frost resistance varies depending on the surface type (Figure 6), and the manufacturing year. The worst properties are found in exposed aggregate concrete, ceramic tiles and uncoated patterned concrete. In addition, concrete facades made before 1980 generally have poorer frost resistance than newer facades.

Figure 8. An example of original facade, plan and section drawings of a building. 3.1 Quality of the research material

Like Maki6 et al. (1994, p. 66-68; 82-84) imply, load-bearing panels are generally shorter than non-load bearing panels, i.e. less than a room wide. The load-bearing Therefore, only non- facade of a room is typically put together from two or more panels. load-bearing panels were studied for the compatibility with current recommendations for room widths. 150mm was reduced from the panel dimension to acknowledge the loss of width resulting from the connections with crosswalls. As seen in Figure 11, only 0.5 of all non-load-bearing panels are not wide enough in the light of the present recommendations. 85.8% comply directly with the recommendations to one or more rooms, and 13.7% are wider than recommended and, thus, applicable as well. When it comes to the main rooms of a flat, the majority of panels are compatible with two-

Figure 12. Main panel types from left to right: blind load-bearing panel; typical non- load-bearing panel with a normal window, non-load-bearing balcony back wall panel. 4.5 Types of wall panels

Figure 20. Typical hollow-core slabs: one, two or three rooms long

the purposes of this study: every building represents the erstwhile design practice: regardless of the time taken by the construction. An effort was made to roughly balance the building type distribution to slab blocks and tower blocks by using a ratio of 3:1 (see Figure 1). Based on a comparison sample (N=1125) acquired from ARA's Register of Real Estate (2013), tower blocks were slightly overrepresented among the studied buildings compared to all contemporary publicly funded production with their portions being 29.4% and 24.3% respectively. As some flat types are noticeably more common in either slab or tower blocks, this has a slight effect when considering their prevalence in a wider context.

Figure 5. Two-room flat types. rather clearly divided between building types. Each main type has its distinctive shape The most common two-room main type generally appears in slab blocks. It spans across the building and is usual flat in-between or next to a singl in two directions, regardless of t y located opposite to an identical flat with a one-room e type 3-1 flat. All the flats in the main type only open heir position in the building. Inside the flats, the rooms are mainly located based on their need for a window, which places the habitable rooms next to fagades with the hall, ba hroom and possible walk-in closet in the middle. As is logical from a technical standpoint, kitchens and bathrooms usually lie next to each other. The size and shape of their shared duct varies, as does the room it is located in. The living room is usually across the hall from the kitchen.

structural elements generally remain unchanged.

Figure 8. Examples of flats outside the defined types. frame system used, this could be expected. Many of the units that remain outside the defined types are clear variations of those. For example, the first and third layout in Figure 8 are very close to 2-1B and 1—1A, respectively. The same appears to be true for flats with five or more rooms, although hese are extremely rare. Individual rooms are also similar in shape and size to those of the recognized flat types. Since room sizes are, to a large degree, determined by the frame system used, this could be expected.

Data on 355 172 publicly financed dwellings from ARA’s Register of Real Estate (2013) was compared to statistics on privately financed dwellings built during the corresponding years. Figure 10 presents the comparison. Row houses are included in the numbers to retain comparability because they have been combined with apartment blocks in some of the sources used. Since, at least among publicly financed buildings, the different building types roughly follow the same trends in average area (ARA, 2013), the effect of including the row houses should be minimal for the current purpose. The years used in compiling the statistics vary between the sources: ARA (2013) uses the year the loan for the project was granted, Kakko (2011) and OSF (2007) use the year of completion, and Laine (1993) uses both in different tables and figures. Therefore, the numbers presented are not accurate as annual snapshots, but due to the gradualness of the change, they are usable for examining general trends.

5.4 Correspondence between rental and owner-occupied housing Figure 10 shows that in the 1970s, the biggest difference in average dwelling area was not between financing methods but between tenure types: in publicly financed projects the average size of owner-occupied dwellings grew, while rental dwellings initially got smaller and then stayed roughly the same. Tenure-based data is not available fo privately financed dwellings, but similar figures seem likely considering the minima difference in the average area as mentioned above and nearly identical portion o rental dwellings — 57.5% in publicly financed and 59.2% in privately financec production (Statistics Finland, 2014). Figure 10 shows that in the 1970s, the biggest difference in average dwelling area was

To examine further whether there is a difference in the average areas of flats with equal numbers of rooms but different tenure types, a random sample of 2000 owner- occupied flats (Etuovi.com, 2014) — 500 for each room count — was compared tc 152 722 rental flats (ARA, 2013). A sample was also taken from the research material consisting of 90 buildings, spread evenly among the year range and containing 2545 flats in total, including both tenure types. The annual average areas of the aforementioned samples are presented in Figure 11. The average flat sizes for the whole year range were nearly identical in the samples, the largest difference occurrinc with four-room flats, but even this was only 2.9m?. Annual variation in the average areas is minimal in the comparison samples, and even in the research material the variation appears to mainly depend on the sample size: the higher the number of flats examined, the smoother the graph. aforementioned samples are presented in Figure 11. The average flat sizes for the

Table 1. Age cohorts used in literature. Greater geological eras and economic cycles are also given as a reference.

Table 4. Typical values in the age cohort (Article III) Notes: *) 2.8 m high panels; **) 1.2 m wide slabs. Although the floor height is the same in all buildings (2800 mm, the erstwhile minimum) the room heights (and respectively, the heights of load-bearing parts of panels) vary according to the floor type. The most significant floor types are in-situ cast slabs and prefabricated hollow-core slabs. 64% of the buildings have in-situ cast slabs, whose thicknesses range from 150 to 250 mm. They are typically 200 mm thick resulting in 2600 mm high rooms. 27% of the buildings have 1.2 meter-wide hollow-core slabs, 90% of which are 265 mm thick resulting in a room height of circa 2500 mm. Thicknesses of load-bearing interior walls range from 150 to 220 mm. The thermal insulation of exterior walls is typically 120 mm (mode value), which equals to a U-value of 0.40 W/m2kK. (Article III). However, the amount of insulation varies from 75 to 150 mm, depending on the norms in force at the time of the building’s construction (Raw data of Article III). Table 4 summarizes the typical properties of components. data of Article III). Table 4 summarizes the typical properties of components.

Table 5. Relations of newly constructed and demolished floor area of different building types (Raw data of Article |). The exact numbers and floor areas of demolished buildings are provided in Chapter 3.1 (see e.g. Table 3 and Figures 6, 8 and 9). Figure 18, however, elaborates on the floor areas of demolished buildings by more specific building types. In order to be meaningful, these kinds of figures need to be related to those of new construction. As already stated, the overall volume of new construction in Finland clearly exceeded that of demolition during the examination period, and new construction has continued even in shrinking communities. When the matter is looked at on the scale of the municipalities, the situation is the same: new construction supersedes demolition in every single Finnish municipality. When the municipal-level investigation takes into consideration building types in nine categories (categorization had to be adapted to that used in statistics, Appendix Il), only 8-25 municipalities out of 320 emerge, depending on the building type, where the volume of demolition in that building type exceeds that of new construction (Table 5). The overrun is insignificant in most cases. From this point of view, new construction is a plausible sink for the parts and materials from the demolished buildings at the national as well as the local scale. Since the need for the specific building types also supersedes demolition, continued use may also be a viable alternative. (Article 1). of demolition during the examination period, and new construction has continued even

Table 6. Room count distribution in the cohort (Raw data of Article IV). If it is assumed that the entire cohort’s degree of prefabrication follows the results of this study, 84% of the buildings would have prefabricated square panel facades and 27% would have hollow-core slabs (Article Ill). Thus, 25 517 buildings would have panel facades and 8202 of them would also have hollow-core slabs. Using data from Table 4, Table 8 estimates the quantities of panels and panel surfaces in them. Table 4, Table 8 estimates the quantities of panels and panel surfaces in them

Table 7. Amounts of flat types in the entire cohort and their proportions with regard to all flats and all homes from all times. However, this assessment can be expected to exaggerate the extent of the reserve more significantly than the flat type quantification, because the degree of prefabricatior was notably lower in the early 1960s, be it that it kept rising the entire 1980s. Moreover the calculation ignores possible losses of components resulting from existing damage or damage occurring during deconstruction. As noted earlier, the reuse of these panel: is currently limited to low-rise low-density housing due to sound insulation requirement: (Article Ill). Detached houses, for instance, account for one-third of annual nev construction of homes in Finland. When the panels of an average block of flats coulc make up nine houses, the entire stock could contribute to circa 230 000 houses. This represents roughly the construction needs of two decades at the current pace. represents roughly the construction needs of two decades at the current pace.

Table 8. Quantification of panels and panel surfaces in the entire cohort.

Table 11. Flat types in demolished blocks.

Table 2. Volumes of demolished buildings by building types Table 2 shows that by number, the largest group was detached houses (16 319), followed by utility buildings (15 335) and holiday cottages (7460). Despite their great number, these buildings are small in size. Consequently, the order is different if measured by floor area: industrial buildings (1,7 million m?) are followed by detached houses (1,4 million m?) and public buildings (1,3 million m?). Commercial or office buildings (1,2 million m?) and warehouses (1,1 million m?) are remarkable groups, too. Table 3 presents the volumes of RB and NRB in the data. The shares of RB and NRB are almost equal, but NRB dominate demolished floor area. Demolished NRB are in general much larger than RB.

Table 3. Volumes of residential and non-residential buildings

Table 4. Volumes of demolition in communities with different zones of urbanization according to the building type

Table 5. Construction material of the load-bearing structure Tables 5 and 6 present the distribution of the construction material of the load-bearing structure in general as well as for different building types. While timber buildings form 87% of known records in number, timber (41%) and concrete (36%) together compose the majority (77%) of floor area for known records. Calculated average area demonstrates that demolished wooden buildings are usually small and concrete buildings large.

Table 7. Construction method (prefabricated / built in-situ / unknown) by material Table 6 shows that wood was the dominating material by floor area for detached houses, row houses, holiday cottages, utility buildings as well as agricultural buildings. Concrete, on the other hand, prevails in the categories of blocks of flats, commercial and office buildings, warehouses, industrial buildings and transport buildings. Quite surprisingly, wood and concrete are almost even for public buildings. The information on the construction method of the load-bearing structure could be traced down for 8841 buildings (17%) or 3168015 m? of floor area (35%). Of these, 2107 (24%) were prefabricated with 1073 340 m? (34%). Table 7 shows the figures by material. prefabricated with 1 073 340 m* (34%). Table 7 shows the figures by material. 4.5 Building year

Table 8. Number and area of demolitions in different decades

Table 11. Average age at the time of demolition by building type In residential buildings, demolished row houses showed life spans two decades shorter than detached houses or blocks of flats. In non-residential buildings, the longest life spans occurred in utility buildings (47 years) and public buildings (41 years). All in all, over 80% of the demolished floor area was located in buildings that were less than 60 years old. Figure 4 shows the age division in detail and Figures 5 and 6 for RB and NRB. Detached houses and blocks of flats showed the highest average ages of the demolished stock, over 60 years. Buildings classified as “others” had the shortest life spans, little over 30 years. Tables 10 and 11 show that NRB have a shorter life span than RB. However, these ages should not be confused with the average age of the whole stock that includes buildings that have been demolished prior to 2000 or after 2012 and buildings that still exist.

Table 12. Number and area of demolished buildings by reason for demolition As seen in Table 12, the data shows clearly that removals from the building stock are a result of conscious deliberation. The most usual reason for demolition was to give way for new construction. Destruction or abandonment explained only a small minority of demolition decisions. The group of "other reasons" was accountable for the rest. If measured in floor area, new construction and other reasons were equally significant. measured in floor area, new construction and other reasons were equally significant.

Table 13. Reason for demolition by area type

Table 15. Motive for demolition by actualized or planned new construction

Table 16. Demolished apartments in growing and shrinking areas and different building types As seen in table 16, 28 158 apartments (an average of nearly 2350 apartments pe year) have been demolished since 2000, the majority of them in detached houses. 61% of removed apartments were located in growing municipalities, which dominate th demolition of apartments in all building types. The share of apartments demolishe from blocks of flats is highest in growing municipalities and lowest in steady-stat communities. Table 17 elaborates on the location of demolished apartments withil zones of different degree of urbanization. Inner cities prevail in the demolition o apartments in all other building types except in detached houses, apartments in whicl were demolished in greatest numbers in outer cities. Inner cities clearly stand out fo blocks of flats, as every third apartment demolished in city cores was located in them. locks of flats, as every third apartment demolished in city cores was located in them

Table 17. Demolished apartments in different building types by different zones of urbanization

Table 3. Number and share of vacant homes in the buildings of the data.

Table 4. Share of vacant homes in the whole building stock.

Table 5. Number and share of buildings touched by vacancies.

Table 6. Duration of vacancy in different building types.

Table 7. Area and share of buildings touched by normal and problematic vacancy and completely empty 8uildings.

Table 8. Number of buildings with problematic vacancy from different construction materials.

Table 9. Area of buildings with problematic vacancy from different construction materials.

Table 11. Area of buildings. Problematically vacant buildings include long-term completely empty buildings.

Table 14. Number of row houses. Problematically vacant buildings include completely empty buildings.

Table 15. Area of row houses. Problematically vacant buildings include completely empty buildings.

Table 17. Area of blocks of flats. Problematically vacant buildings include completely empty buildings.

Table 21. New construction on the plots of demolished detached houses. To consider possible futures for vacant buildings, replacement behaviour of buildings was studied by comparing demolished and built buildings on the same plots. In total, 10 520 pieces of real estate had residential buildings demolished and new buildings built in 2000-12. In 81% of them, new construction was residential. As Table 20 shows, detached houses were usually substituted with detached houses and blocks of flats with blocks of flats. Row houses, however, were most often replaced with non- residential buildings. Tables 21, 22, and 23 zoom on the replacement behaviour in urban and rural area types. Regardless of the degree of urbanity, detached houses were most often replaced with detached houses. Exchange into non-residential buildings was notable in the countryside. Row houses were usually exchanged into blocks of flats in inner cities; more often into blocks of flats or detached houses than row houses in outer cities; and usually into detached houses in city rings. Replacing old row houses with row houses was common only in the countryside. However, the majority of row houses in all area types, except inner cities and sparsely populated countryside, were exchanged into non-residential buildings. Replacing blocks of flats with the same type prevailed only in inner cities and rural towns, i.e. community centres. In outer cities, blocks of flats usually made way for detached houses, and in all other area types, for non-residential buildings.

Table 23. New construction on the plots of demolished blocks of flats. Since tenure and the building type affect the range of measures owners can conduct, Figure 15 shows the building and tenure types of all homes demolished between 2000- 12. A comparison to tenure types of vacancies reveals that rental homes are overrepresented amongst demolished homes in comparison to vacant homes. Alas, the data does not allow distinguishing between professional and non-professional private owners. However, a significant share of demolition in the private rented stock took place in multi-family buildings, which implies to professional ownership. As could be expected, almost all demolished owner-occupied homes are detached houses. They are also more prevalent in the whole of the demolished stock than in the problematically vacant part of the stock, let alone the normally vacant part.

Table 6. Acoustic indexes (dB) in Finnish building regulation from 1955 on (Lahdensivu et al., 2015, p. 51).

*Buildings where the relevant information could be determined from the research material In both studies, the degree of prefabrication rises considerably towards the ends of the studied time periods. A similar shift occurs with the frame types, as the concrete crosswall frame becomes more common towards the 1970s, replacing other types such as brick walls or in situ cast concrete frames (Maki6 et al., 1994). Considering the convergence the two studies have — and that BES-buildings, which are prefabricated and use a crosswall frame, started to take over in late 1970s (Maki6 et al., 1994, p. 68) — it appears that the differences would be likely to even decrease after 1975. — it appears that the differences would be likely to even decrease after 1975. Table 7. Comparison of structures between research material and Makio et al. (1994).

*Buildings where the floor structure could be determined Table 8 presents the distribution of the most common prefabricated floor structures in the research material of the current paper. Of these, the hollow core slab is clearly in the majority, increasing notably for the last five of the studied years. Makio et al. (1994) do not present actual numbers on the distribution of different floor types over the years, but the general trends appear as similar to the current study with in situ cast floors dominating the 1960s and the early 1970s before giving way to prefabricated solid slabs and hollow-core slabs. The dominance of the hollow-core slab coincides with the statements by Makio et al. (1994, p. 41) and Neuvonen (2006, p. 218), both of which mention this slab type as eventually becoming the most common choice. mention this slab type as eventually becoming the most common choice. Table 8. Distribution of the most common floor structures in the research material.

Table 1. Recommended areas for publicly subsidized flats (Makio et al., 1994, p.194). Besides the guidelines provided by officials, good construction practices have been promoted in the RT Building Information File since 1943. The RT File, which is still updated and widely used, was founded by the Finnish Association of Architects for post-war reconstruction. It has been published by a non-profit foundation since 1972. (Maki6 et al., 1994, p.278). At that time, the File provided space requirements for furniture and equipment in living rooms, bedrooms, kitchens and bathrooms (RT 930.10, 1965; RT 930.20, 1974; RT 930.30, 1974; RT 930.40, 1974; RT 930.50, 1974; RT 935.50, 1966; RT 936.50, 1965), but instructional layouts were given only for bedrooms (RT 935.50, 1966; 50 configurations) and bathrooms (RT 936.50, 1965; 26 configurations).

Table 3. Occurrence of recognized flat types in the buildings of previous studies. count, the most common type was the X-1. The dominating factor in determining the usefulness of the types is how much of the whole building stock they encompass. Though few in number, the existing applicable works using the concept of typical buildings seem to comply with the flat types defined in this study. Within the chosen year range, Makio et al. (1994) present 15 landings, Parnanen et al. (1994) two buildings and Rantala (2008; 2009) eight buildings. Table 3 shows the occurrence of the types in them. As in the current study, for each room count, the most common type was the X—1. In addition, the research material was compared to a sample of flats for sale on Etuovi.com (2014). Table 4 presents the coverages of types for the research material and the comparison sample. The biggest difference appears with the largest flats. This could be expected, since those flats also exhibited the most variance within the

research material and obviously have the highest potential for different layouts. Nonetheless, the flat type coverage among different room counts is consistent between the samples: the percentage is highest for two-room flats and decreases for other room counts in the same order. This is also true when considering the coverages of the most common flat types — which are the same in both samples — of all units with equal room count. common flat types — which are the same in both samples — of all units with equal room Aside from the current research and the aforementioned other studies, there is no data available on the number of specific flat layouts produced. Therefore, determining the correspondence further between the research material and all comparable construction ‘elies on studying more general properties of the flats. This study is divided into a orogression of comparison pairs, where each stage widens the context, in order to aventually evaluate the applicability of the types in the scope of all Finnish apartment locks built during the studied period. Nonetheless, the flat type coverage among different room counts is consistent between available on the number of specific flat layouts produced. Therefore, determining the

Even if the defined types only applied to publicly financed apartment blocks — with full generalizability within that category — they would still cover 33.5% of the dwellings in apartment blocks whose construction began between the years 1968 and 1985 (Kakko, 2011; Laine, 1993). However, based on the comparisons presented above, the flat types appear equally applicable to the privately financed dwelling stock. This brings their coverage to the figures presented in Table 5 and the total number of covered dwellings to 387 884. In addition, there obviously was no immediate and complete change in housing production at either end of the studied time period. Therefore, the coverage of the flat types should well extend beyond the studied era in both directions. It is also possible that some of the flat plans were used in row houses built with the same production methods due to the similar form of the building floor. same production methods due to the similar form of the building floor.

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