Inspiration

House on the End

1200 Works takes the ‘raw is more’ approach on a London end-of-terrace cast from fibre-reinforced concrete

The facade of the House on the End, 1200 Works’ Maser Medal-shortlisted infill development in south-east London, is not what it seems. From the two horizontal bands of in-situ white concrete that continue the line of datums along the two-storey Victorian terrace, the casual observer might assume that the floor slabs tie in neatly with the neighbouring homes. But in fact, the House on the End contains three full-height levels: the ground floor is sunken 300mm, and the real slabs concealed by the windows’ dark bronze over-panels.

The gentle duplicity is worth noting because this is otherwise a building that conceals nothing. Hugo McCloud – the founder of 1200 Works and, with his wife and two dogs, resident of the House on the End – has crafted a home that he describes as “very much ‘raw is more’”, without so much as a skirting board to hide behind.

The structural frame is built from in-situ concrete, largely exposed internally and faced with solid brick on the outside. Concrete was chosen partly for its aesthetics, partly for its thermal properties and partly for logistical reasons. The site was a tight 73sqm scrap of land previously occupied by garages, with very little room to store materials, which meant the site team needed to make the frame weathertight as quickly as possible.

To this end, the concrete specified was self-compacting and barely contained any steel reinforcement bar, which helped to reduce site work. McCloud chose to use a proprietary fibre-reinforced concrete, which derives its flexural strength from strands of polypropylene and steel. This is only the second house in the UK to adopt this approach, after the Concrete House in East Sussex featured in CQ 274.

Not only did the fibre-reinforced concrete save time on site, it also reduced the embodied carbon of the structure by cutting both the amount of steel and the amount of concrete cover to protect it – the slabs only needed to be 180mm thick and the walls 150mm. The carbon impact is further minimised through the use of 40% GGBS in the mix, which also lightens the tone of the raw interiors.

The concrete was initially cast using melamine-faced boards, but McCloud found that this resulted in more blowholes that required post-finishing work. On the soffits and first-floor walls, however, the team turned to film-faced ply boards, which worked far better, allowing the concrete to be left as struck.

All of the concrete has been precisely set out, with joint lines running from the concrete walls to the soffits and on to the ply-clad walls and built-in cupboards. This also sets the sub-grid for the electrics and lighting, which are cast in through the slab. Even the pictures are hung in alignment with the tie holes, a detail that needed advanced planning, as fibre-reinforced concrete is a destroyer of drill bits. To get round this, a series of – more forgiving – mortar-based fixtures were cast in.

The level of detailing was dictated by the raw finish, McCloud explains. “As an architect, you’re forced to think more and ultimately create better, crisper details because you don’t have the luxury of paint or plaster to cover your mistakes. There are no architraves, no skirtings, nowhere to hide junctions. We had to rethink how we were going to construct it – redesigning how the timber flooring would meet the concrete, for example.”

Throughout, the concrete structure is complemented by limed timber and brass fittings, as well as polished concrete worktops in the kitchen and bathroom and terrazzo flooring on the ground floor. Granite rather than marble lends a monochromatic tone to the terrazzo, and is also used on the small patio.

If the decor sounds a little severe, it is a very liveable space, he says, abetted by the thermal properties of its concrete shell. “Even when it’s 30˚C outside, as long as you shut the windows during the day and open them in the evening, the building doesn’t get above 22-23˚C.” The reverse is true in winter, he adds. “It just seems to maintain a constant temperature, no matter what the weather is outside. We barely turn on the heating at all. For about 11 months of the year, I think the house runs on the heat of my wife, me and the two dogs.”

PROJECT TEAM

Architect 1200 Works
Structural engineer Elliot Wood
Main contractor Altus Construction
Concrete supplier Cemex

Photos Lily Maggs; 1200 Works