Markku Norvasuo (@markkuno.bsky.social)

Horizontal building extensions: potential in Finnish blocks of flats | Buildings & Cities Horizontal extensions of blocks of flats are a promising, but little studied, approach for circular and socially sustainable urban renewal. Based on research-by-design of real cases in Espoo, Finland, this article explores horizontal extension opportunities in suburban housing estates built between the 1960s and the 1980s. The analysis discloses how different modes of extension affect urban block morphology, flat distribution in buildings and qualities of individual dwellings. The results confirm that horizontal extensions provide a substantial and feasible approach in renewing ageing housing estates. As horizontal extensions help to postpone usable buildings’ demolition and extend the life of carbon-intensive concrete structures, they can limit the building sector’s carbon emissions currently when rapid climate change mitigation is a priority. They offer moderate possibilities to increase estates’ density, while preserving the greenery and social spaces that characterise the original neighbourhood unit designs. Furthermore, well-designed horizontal extensions can adapt flat distribution to meet current market demand, improve accessibility for the elderly and the disabled, and enhance the experiential housing quality, especially in gable flats. Owing to standardisation of housing estate planning and production in the studied era, comparable potentials are expected to be found in other cases, both nationally and internationally. https://doi.org/10.5334/bc.783