By excavating the garden to basement level, ZCD Architects created a new living space for this late 19th century home. 

timber clad extension with green glazed door - grand designs

Image: Charles Hosea 

Faced with a tight site that already had an extension, but a brief from the client to create a larger, brighter living space and an extra bedroom, ZCD Architects had to think laterally in reinventing this three bedroom maisonette occupying two storeys of a four-storey Victorian terrace.

The solution was bold but simple - excavate the garden down to the basement level in order to re-work the internal layout. In this way, the architects have subtracted from the space, rather than adding to it, to rework the home to meet the client’s needs. 

Bright idea

internal of basement extension with roof light and internal courtyard - grand designs

Image: Charles Hosea 

The glazing to the courtyard is large and fully openable, further brightening the new kitchen and living space. Natural light is further increased by a small internal courtyard which can be fully opened on to the room - helping not only to blur the lines between the indoor and outdoor spaces, but to bring light to what could have potentially been the darkest part of the entire property. 

Read more: 4 build projects with internal courtyard gardens

The sunken place  

people in a sunken garden with a firepit and seating - extensions - grand designs

Image: Charles Hosea

Larch has been used for the external cladding of the replacement extension, creating strong horizontal lines that carry around the courtyard garden, including the stairs climbing back to street level. The architect opted for a white-stained timber for its reflective qualities, to help the sunken garden feel lighter and brighter. The original retaining walls and board marked concrete have been left exposed, with new planting and seating creating a social space. 

An extra bedroom 

plywood bedroom with access to roof terrace - extension - grand designs

Image: Charles Hosea

On the upper floor, the architects have thoughtfully rebuilt to make the most of the space. This enabled a bathroom to be replaced by a small bedroom, in which the structural fins have been left exposed to help the ceiling height feel more generous. 

A bespoke bed fits snugly into the room, along with custom storage that cleverly makes the most of the compact space. From the bed, a new outdoor terrace can be accessed via a half door. 


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