Vertical House Extension in Ickenham, London

Vertical House Extension in Ickenham, London

The single-family detached house was built in 1935 resembling every other house on this leafy street of Ickenham. It was extended in the early 2000s but the loft conversion yielded only one bedroom with a ceiling height of 2.2 metres, sloping to 0.8 metre and posing a hazard of bumping one’s head.

The client requested a new first floor creating far more space than a normal attic. We proposed to rebuild the roof significantly higher with the same slope and without any dormer. This would yield a 4.1-metre high ceiling sloping to a minimum of 2 metres and preserving the character of the house.

In order to secure planning permission, we held a pre-application meeting with Hillingdon and supported our case with a study of the neighbourhood. The planners appreciated our approach which eschewed the typical “box on the roof” in favour of an unbroken gable. We received planning permission in 2025 on the first attempt.

Following our suggestion, the client hired the environmental consultant Genous to support their sustainability ambitions. Together we designed a roof with 36 solar panels arranged around six skylights. Genous’s design, including an inverter, a battery and a three-phase mains connection, enables the house to supply up to 16 kW of solar power to the grid at peak sunshine, earning the client money and making the whole street more sustainable. A new heat pump is partially funded by the government’s Boiler Upgrade Scheme.

We drew the new roof as a deep timber-and-steel structure, allowing 22 cm of non-combustible insulation internally and 5 cm externally, for an almost Passivhaus performance. The skylights and windows, all triple-glazed, are also protected from the sun: the skylights have external roller-shutters and the southern window is shaded by an external venetian blind made in Germany.

The interior is light and spacious with a palette of maple wood and white plaster. In the shower room we used giant aqua-coloured tiles and designed a bespoke vanity in maple and Corian. We directed all artificial light onto the ceiling to avoid seeing light sources directly.