Steinlia AS completed a prefabricated roof extension to a mid-19th century two-storey brick terrace home in the south London borough of Southwark.

Emerging Oslo-based architectural firm

The extension provides new light-filled living spaces to meet the changing needs of a young family, largely prefabricated using light-weight composite materials in order to reduce construction time and overcome site access and structural constraints.

It also provides new views across the neighbourhood, and a glazed staircase roof connects the inhabitants’ daily life with the English sky, while drawing light into the original part of the house.

While allowing the inhabitants to remain in the original part of the home during the construction period.

Steinlia’s design provides two new living and sleeping rooms and a generous bathroom, connected to the original part of the house via an extension to the home’s central staircase.

The staircase roof is fully glazed to draw daylight into the original part of the house, and to register the changing English weather and light throughout the day and year.

Steinlia designed the exterior with a modest appearance, responding to the existing terrace and strict local planning requirements, with sizable windows aligned with original façade features below.

Wind-driven natural ventilation maintains airflow and a comfortable interior climate.

The main structure of the extension is built using E-glass/epoxy skins cored with recyclable PET foam. The materials were chosen for their high strength/weight ratio, insulating properties, recyclability, smoke and toxicity properties, good mechanical performance, and aesthetic qualities.

Never before implemented in this way in architectural construction

After 3D scans of the original structure, the panels were CNC routed and built. The extension was then assembled in Germany before transport to the London site.

Its installation took 2 hours in July 2020, with the extension lifted and glued onto supporting beams mounted between the original party walls. Preparatory and finishing works/fitout were carried out by local builders.

The design presents a prototype for future development of similar buildings in constrained urban situations. The extension provides a canvas for the rich and colourful interiors by the inhabitants, easily changed over time, reflecting the family’s life and personality.

The completed project allows the inhabitants to continue their lives in the home and neighbourhood, and provides new qualities, light and space.

(perhaps for generations to come)