A modest terrace in East London was transformed into a striking and sustainable modern home by a tasteful timber extension project – courtesy of architects and TDUK members Studio Manifest.
Among the alterations was a timber-clad wraparound ground-floor rear extension with a dramatic ‘sawtooth’ pitched roof. The design creates a flowing, light-filled communal space connected to the garden.
Timber frame and wood fibre insulation lowered the project’s embodied carbon by an estimated 50% as compared to a build using standard materials; © David Valinsky
They also extended upwards: a loft extension across the main house created a new second floor. All in all, the improvements added a generous open-plan kitchen and living space with access to the garden, while the vertical extension added two new bedrooms in the loft with great views of London.
By using a timber frame and wood fibre insulation for Pitched House, Studio Manifest believe they have reduced the project’s embodied carbon by 50% as compared to a build using standard materials.
Taking influences from the local area
The primary brief from the clients was to modernize the house. They wanted to add space and upgrade the house thoroughly to modern standards. They wanted more flexible spaces, and were also keen to use lower energy approaches.
“There is a connection to cloth merchants in the history of the area,” recalls Ben Powell, architect and Director at Studio Manifest. “Weavers Fields is nearby, for instance, and we started thinking about ways to express different overlapping forms. We liked the idea of wrapping timber around the building to give the sense of a sheet of fabric.”
A ‘sawtooth’ rear extension
This all informed the ground-floor extension, which extends into the garden – replacing a low-quality, leaking lean-to at the back of the house – and into the side-return to gain some extra width. The extension is a timber frame stud system using Siberian larch: 250mm timber studs bolted together with timber studwork in between. There is a striking zig-zag ‘sawtooth’ design to its roof.
“There are two pitched volumes which interlock, which creates a big open-plan kitchen, living and dining area,” Ben tells us. “The design was informed by the existing party wall: the angle of the pitch was set by the neighbouring house and existing roof. The second roof is a little higher. Offsetting them created a little more energy and interest to the rear elevation, and gains the extension a little more height.”
A generous, extended kitchen and living area; © David Valinsky
Simple strip foundations went under the new walls. The extension is clad in Scottish larch supplied by Russwood, which was cut on site. This vertical cladding is extended down slightly over the rear windows to provide a degree of solar shading.
A small outdoor courtyard area was kept in the side passage to break up the space and bring in plenty of daylight to the original house. The kitchen cabinets continue the timber theme, using smart-looking birch plywood fronts supplied by Plykea.
A new upstairs
Timber, being a lightweight material, proved ideal for the roof extension which added a second floor to the building, providing two generous bedrooms and an ensuite bathroom. The first floor was reconfigured to create a more spacious bathroom, complementing the already existing two bedrooms. Timber joists run from party wall to party wall, both in the rear elevation and in the center of the house. Apart from a few steels at ground-floor level, the whole project is timber, including the stairs. The windows are composites: aluminum on the exterior; timber inside.
The extension would be visible from a couple of side angles, so the colour palette was a consideration. “We had a materials palette in the planning application,” Ben says. “The colour temperature of the wood complements the existing brickwork nicely.”
Construction of the timber frame extension
They were also sure to follow good practice during construction. “To avoid water ingress, the works were protected with a big tin “hat” – both for the existing building and the new timber going up.”
Wood fibre insulation
“We now use natural fibre insulation pretty much exclusively on our projects,” Ben reveals. It’s another factor that helps reduce the project’s overall embodied carbon. “We’re finding that wood fibre insulation products from, say, Schneider or Gutex are becoming less and less expensive,” he goes on, “as is British-made hemp fibre insulation.”
Pitched House was the first project that the builders had used these products, and Ben’s pleased to note that they have since used it on a lot of their projects.
“We can get slightly thinner wall buildups by combining the timber frame with wood fibre insulation. Because it is breathable we don’t need a cavity inside: we save between 50 to 100mm. If you’re working on a project where the end value is £10,000 per square metre that becomes quite a significant space gain.
“There’s also better thermal mass than synthetic insulation, which means better temperature regulation in both cold and warm weather. Another advantage is that you can put it directly onto existing brickwork, because it’s breathable. That said, there does come a point of thickness, about 80mmm, where our suppliers recommend putting a membrane in the wall when it goes up.”
“On other timber projects, we have worked with Natural Building Systems, who have a great plywood panelised construction system that is completely demountable, and we are looking to use it on all of our new build schemes. They use a plasterboard with a lime skim and they’re comfortable that this replicates the breathability of a traditional lime render, so we have adopted this approach on our builds.”
© David Valinsky
Wood fibre insulation does prompt some questions from Building Control.
“As we’ve worked our way around London boroughs they seem to be getting used to it,” Ben explains “but we have to had to provide them with data sheets and demonstrate that the insulation isn’t combustible. Nothing too onerous or complicated, however.”
Programme advantages of timber
“With brick and block construction, you don’t get a sense of the form and the shape of the building for a few weeks, at which point it’s very difficult to adjust,” Ben says. “Whereas with timber stud work it takes shape in a few hours. And if we need to make adjustments, it’s fairly easy to do.”
Studio Manifest will use screw fixings wherever they can, avoiding nails, for more flexibility and to better allow for the possibility of reuse at the end of the building’s life-cycle.
© David Valinsky
Studio Manifest are based in London and work across the whole of the UK. They specialise in residential design of all scales, and prioritise the use of timber in all of their projects.
