Structures and built form

The structure and material largely determined the basic nature of building plans, at least until the modern era disconnected the load-bearing structure from the spatial solution. Up to the first decades of the 20th century, Finland was largely rural, construction was mostly vernacular and massive horizontal log structures dominated the building stock. The Finnish timber construction technique was relatively modest in comparison to the Central European one, and the natural span of the tree trunk could rarely be superseded. As a result, the built form of most pre-20th century buildings (churches excluded) consisted of smaller and larger parallel log rooms whose dimensions were typically around 4–5 meters and around 8–10 meters at the maximum in one or one and a half floors. The plan types of historical houses are well documented from the simplest form of single log rooms to the more refined ‘Karolinian’

plan and its derivatives (Korhonen, n.d.).

In timber construction, the next development phase was the light-frame construction, but the fact that the logs were now sawn into studs and beams did not change the limits of their spans. The construction method became prevailing as a result of post-WWII resettlement and reconstruction, which was implemented with the help of type-planned 'veteran houses'. This type of housing factually encompassed large numbers of designs that differed from each other only slightly; they typically had a fourfold square plan and one and a half floors (Kammonen, 2012: 39–45). Wooden two-floor blocks of flats were also typical to the post-war era (Neuvonen, 2002: 85;

Standerstskjöld, 2008: 81), but the literature virtually ignores them, perhaps because they were and still continue to be considered as temporary. Although the veteran house type fell out of use by the 1960s, Finnish detached housing has been characterized by type planning and prefabrication ever since. Ruotsalainen (2011) and Kammonen (2012) offer a cross-section to the historical development of such housing. In addition to providing historical overviews, the former focuses on the type-planned housing of the 1960s and the 1970s while the latter examines contemporary prefabricated houses.

Although Ruotsalainen (2011: 60–5) briefly applies typological methodology, neither of the studies is systematic enough to provide generalizable knowledge about the plans of their targeted cohort.

Multi-storey construction emerged in the end of the 19th century. A vast in-depth research project into blocks of flats from all times was conducted during the 1990s and 2000s (Mäkiö et al., 1990; 1994; Neuvonen, Mäkiö & Malinen, 2002; Neuvonen, 2006;

2015), but it focused on structural options, materials and heating, ventilation, air conditioning (HVAC) systems and largely ignored the plan design. At first, walls of blocks of flats were made of load-bearing masonry. Their horizontal load-bearing structures consisted, however, of timber beams, which delimited the horizontal dimensions of the rooms to the natural length of the tree trunk. Thus, the plans of early blocks of flats are also formed by sequences of rooms in two or three rows. Although steel I-beams were also taken used in 1910s and reinforced concrete upstand beams prevailed from the 1920s to the 1950s, the principles of the plan formation remained unchanged. Brick walls and concrete upstand beams were replaced in the course of the 1950s and 1960s, first by in-situ cast concrete walls and slabs and eventually by prefabricated concrete panels. As the maximum span of both in-situ cast slabs and prefabricated massive slabs was 5–6 meters, their introduction had little impact on plan design. Post-beam or post-slab construction, which would have freed the plans from the limitations of the load-bearing walls, did not become common in Finland. Instead, the introduction of the pre-tensioned prefabricated hollow-core slab in the beginning of the 1970s offered this opportunity. (Neuvonen, 2002). Unlike the more historical construction, plans of multi-storey buildings have not been systematically investigated

in the past. Mäkiö et al. (1990; 1994) do present a selection of plans for blocks of flats from 1940 to 1975, while Neuvonen, Mäkiö and Malinen (2002) and Neuvonen (2006;

2015) only include a handful of exemplary plans for buildings that are older or younger than that. None of the aforementioned, however, takes any stance on the prevalence of the plans within the cohorts.

Also Nippala (1988) presents a selection of buildings from different decades – in addition to blocks of flats, detached houses and row houses – that he deems 'typical' for their era. Besides containing information about structure types, the material includes plan, section and facade drawings, which appear to originate from specific buildings rather than being a result of fusing the properties of several buildings. Despite the fact that they have been adopted as the basis for instructions related to buildings' energy certification (Ympäristöministeriö, 2013), their true value for generalization is limited.

As for other building types, the knowledge is fragmented and extremely sparse. To the author's knowledge, no research has been conducted on other parts of the stock, case studies excluded. Due to the constraints set by construction techniques, it can be assumed that multi-storey RB and NRB (such as office buildings, schools and health care buildings) were likely similar in terms of plan design for long. The stylistic features of their architecture have also been classified in detail. Yet, both the aforementioned approaches offer little insight into their functional adaptability. The understanding that can be gained by looking at past design norms and guidance is also very limited.

Nationwide norms on structural design have existed since the 1920s for concrete structures and since the 1940s for timber structures (Finlex, 2016), although the National Building Code of Finland was first issued as late as the late 1970s (Rakennustieto, 2015). This kind of norms, specifying mainly the maximum stresses, reveal little about structural systems and structure types. In addition to the official regulation, however, associations representing engineers (such as the Finnish Association of Civil Engineers, RIL) or manufacturers published additional instructional documents that promoted a variety of alternative structural solutions. The prevalence order of the different options, however, remains unknown. Later renovation-motivated research has had the tendency to concentrate on facades and HVAC, since these are the main objects in need of technical repair. Lahdensivu et al. (2015), however, list structural systems and component types for prefabricated concrete buildings of different functions but, as said, without the knowledge of their order of prevalence or their more specific properties.

Due to the aforementioned decoupling of the structure and plan design, structural norms are, alas, not very helpful with regard to spatial qualities of buildings, which is crucial with regard to their potential for continued use and adaptive reuse. The

publication of architectural design guidance began in Finland in the 1940s. These documents, titled 'Building information (RT) files', were published by the Finnish Association of Architects (SAFA) until the 1970s, when their publication was transferred to a non-profit organization called the Building Information Foundation. Even though the RT files encompass today a wide-range of instructions from plans and details to structures and processes, their focus vested on RB for long. A natural explanation is that architects were likely less involved in the design of NRB. As the activities in commercial and industrial buildings often required long spans, structural engineering dominated their design. Table 2 lists the years when instructions on specific types of buildings were introduced in the RT files. The guidance typically focuses on very specific aspects of a plan, such as dimensioning rooms with given functions, but not on the combinations of these rooms into buildings. Therefore, the RT files are not very useful, either, from a stock-centred perspective.

Building type Year introduced

Storage buildings 1948

Agricultural buildings 1973

Small industrial buildings 1982

Industrial buildings 1993

Warehouses 1993

Sheltered homes 1994

Offices 2000

Public buildings 2003

Schools 2008

Table 2. Chronological introduction of NRB in the RT files.(Rakennustieto, 2015).

In all, the state of research on the built form of the Finnish stock seems not to be extraordinary in international comparison. Typological methods have been used widely in historical research elsewhere, too, but much more sparingly in the investigation of the contemporary stock. Aside from the work of Philip Steadman, whose record includes several graph-theoretical studies on the typology of the British building stock since the 1980s and the relevant methodology (e.g. Steadman, 1983; Steadman, Brown & Rickaby, 1991; Steadman & Mitchell, 2010, just to name a few), there are only a handful of examples of such studies, such as Amole (2007), regarding Nigerian student housing; Ju, Lee and Jeon (2014, touching upon Malaysian blocks of flats, as well as Agyefi-Mensah et al. (2015), concerning Ghanaian public housing.