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Horizontal building extensions: potential in Finnish blocks of flats Cover

Horizontal building extensions: potential in Finnish blocks of flats

By: Jyrki Tarpio and  Panu Lehtovuori  
Open Access
|Mar 2026

Figures & Tables

Figure 1

Matinkylä suburban housing estate in Espoo in the late 1960s: a ‘neo grid plan’ in the making.

Source: Finnish Labour Archives (Työväen arkisto), CC BY-NC-ND 4.0; https://tyark.fi/en/home/.

Figure 2

Floor plan of a lamella building with two lamellas and particularly noticeable transverse room zones (highlighted in one lamella).

Figure 3

Five basic modes of horizontal extendibility of a lamella building.

Note: Extensions are highlighted; modifications to the original building and new spaces are shown in black.

Figure 4

Five selected case blocks and selected case study buildings.

Figure 5

Dwelling distribution in the five case study buildings.

Figure 6

Load-bearing structure: positions of wet spaces (blue) and basic dimensions of the five studied buildings.

Figure 7

Examples of horizontal building extensions in five case study blocks.

Note: Original buildings are presented in dark grey; their extensions in black.

Figure 8

Gaps between buildings that cannot be filled with basic modes of extension (red highlight).

Note: Stairwells are shown in black.

Figure 9

Examples of flat types generated by the five basic modes of extension.

Note: Modifications to the original building are marked in red; other colours indicate the original flat types (the layout is in the top-left corner) and new flats as well as modified original flats (other floor plans). Numbers indicate the number of flats per storey.

Figure 10

Examples of the modified original flats and new flats in the five buildings generated by the basic modes of extension.

Note: Modifications to the original buildings are marked red; selected modified original flats and new flats are coloured.

Figure 11

Original habitable rooms and other spaces affected by the basic modes of extension.

Note: Affected rooms and spaces are hatched.

Figure 12

Flats affected by the basic modes of extension.

Figure 13

Example of gable unit size-modification options.

Figure 14

Example of mid-frame unit size-modification options.

Figure 15

Comparison of size-modification options for the same unit when located in the gable and mid-frame.

DOI: https://doi.org/10.5334/bc.783 | Journal eISSN: 2632-6655
Language: English
Submitted on: Jan 19, 2026
|
Accepted on: Mar 16, 2026
|
Published on: Mar 31, 2026
Published by: Ubiquity Press
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year

© 2026 Jyrki Tarpio, Panu Lehtovuori, published by Ubiquity Press
This work is licensed under the Creative Commons Attribution 4.0 License.