When Jonathan and Zahra Chambers brought in Adam Knibb Architects to design a cross laminated timber (CLT) extension to their Grade II-listed house, he recalls being struck by how the building “seemed to face the wrong way”. It ran vertically down the edge of a large plot, with only a bay window from the living room providing views of the garden, which has a stream running along its edge.
- Homeowners: Jonathan and Zahra Chambers
- Project: Contemporary extension to a listed barn conversion
- Location: Alresford, Hampshire
- Size: 95m²
- Build time: Five months
- Build cost: £250,000
- Value: £1.5million
Working closely with the Chambers, Adam came up with a plan that would “change the social orientation” of the house, which had started out life as a barn in the 18th century, before being converted into a home.
The solution: a 95m2 contemporary extension perpendicular to the house, replacing a 1970s garage block and providing both privacy – by blocking off the view to passers-by and creating a courtyard entrance – and a new contemporary kitchen, dining and living space that would best take advantage of the site’s views and topography.
“We absolutely wanted to have something that was a total contrast to the barn,” Zahra says. “We wanted it to be open plan with a lot of light and windows so that we could actually see our garden.”
The kitchen, supplied by Alresford Interiors, features a kitchen island that allows for views down the garden and to the stream at the bottom.
“I think the planners liked that we were showcasing architecture from two different eras, rather than trying to create some pastiche of a bygone age,” Adam says, explaining the smooth planning process.
And though the building’s listed status meant that English Heritage and the historic team at Winchester Council wanted little change to the existing building, two major works were approved: new glazing and a new front door that would match that on the extension; and the bay window, which wasn’t original, removed and a glazed link added that offset the extension by 1.5m.
“The question we had was how to bring the two elements together without them clashing,” Adam says. “A glass link was the answer: it acts a buffer between the two.”
Building the CLT Extension
Looking to stick to a tight budget and with no pressing time concerns, Jonathan decided against a main contractor and tendered out each package of the build. The main structure is constructed from prefabricated CLT brought in from Austria.
“CLT is a bit more expensive than your standard studwork, but crucially it allowed us to keep control of the building,” Adam explains. “The tolerances are so good with CLT that you can order the glazing off the drawings. One week the building goes up, the next the glass is in and then you’re watertight and the trades can come in. So that worked well for the homeowners.”
The homeowners decided against choosing the more expensive ‘visual grade’ finish for the CLT panels, but still chose to expose them internally, though they have been whitewashed.
Externally the CLT extension is faced with 130mm of rigid Celotex insulation, a UV breather membrane and the battens, onto which the untreated oak cladding is affixed.
To save extra expense, the Chambers decided against plasterboarding out or choosing a ‘visual grade’ finish for the CLT. Instead it has been whitewashed, but otherwise left exposed – the dining room table is even fabricated from an offcut, providing a striking centrepiece to the space – with all the conduits and pipework either facefixed or run through the ceramic tiled floor.
A glazed link connects the existing listed house with the new extension.
Changing Way of Life
The CLT extension has revolutionised the way the Chambers live: the kitchen is sourced locally and mixes plywood units with the pitted Amazonian granite worktop. A bathroom and utility room sit at the far end of the extension, with a discrete living area zoned off from the kitchen.
Across the rear elevation is an expanse of aluminium glazing, including sliding doors, a window seat framed in a bay window, and a slot window in the bathroom, creating the connection to the garden the Chambers craved and leaving them with a contemporary extension to their listed home that redefines the site and the way they can enjoy their house and gardens.