Worn surfaces are deliberately left exposed inside Putney Riverside, a Victorian terrace in London that local studio VATRAA has expanded with a terracotta-coloured concrete extension.

Located in a conservation area along the River Thames in Putney, the terraced home has been revamped for a Sri Lankan couple who purchased it after it had stood untouched for many years.

Its existing structure had suffered severe damage and despite not being heritage protected VATRAA approached its renovation as though it were, revealing and repairing its original elements and complementing them with modern additions.

"Being in a bad condition, the old house did not have many of the old features left," explained the studio.

"All details were gone except for a few key elements – the stair, the floorboards, the plaster walls revealing different layers of plaster and paint after removing the existing wallpaper and the parts affected by damp," it added.

"We decided to use conservation principles to preserve those key features 'as found'. To enhance their beauty, any new additions are complementary but distinguishable from the old."

Entering Putney Riverside, the hallway frames some of the few remaining original features, including a wooden stair, floorboards and plaster mouldings on the ceilings.

With almost 80 per cent of the plasterwork being affected by damp, it could only be kept on some of the wall surfaces, with VATRAA making repairs using "distinguishable but complementary" lime plaster.

The requirement to underpin the home's structure was used as an opportunity to create a basement level at the front of the home, which is illuminated by a lightwell with stairs leading up to the front garden.

"This approach shows an example where practical solutions can be found if we act like a surgeon, only removing the unnecessary parts and making good where needed," said VATRAA.

The colours and textures of Putney Riverside's original surfaces informed the terracotta-coloured concrete extension, which contains an expanded living, dining and kitchen area at the rear of the home.

VATRAA did not extend the side return of the home to create a strip of courtyard-like space alongside the kitchen, which maximises daylight in the long, deep plan in tandem with a row of skylights.

Similarly to the renovation of the existing home, the extension is not designed to replicate the old home but rather provide a modern reinterpretation of it, with pale plastered walls and a stepped concrete floor.

Oak is also used throughout, stained to evoke Sri Lankan wood in a nod to the homeowners' background.

A large French door allows the living area to be opened onto a garden patio with views of the river, framed by the terracotta-pigmented concrete that references the home's original red-brick window surrounds.

To be sensitive to the surrounding conservation area, the existing facade of the home was kept almost identical, with non-breathable masonry paint stripped back and replaced with lime paint and lime-based render.

VATRAA was founded in 2018 by Anamaria Pircu and Bogdan Rusu.

The studio recently completed another extension in London, which was built using reclaimed bricks and features a "brutalist cat flap", and converted a former artist's studio in west London into a house with a six-metre-high lightwell.

The photography is by Jim Stephenson.