This Half-Height Expansion for a Growing Family in London Is a Real Brainteaser
When Andrew and Beth, a couple with a young child, discovered they had a second baby on the way, they realized they needed more space than their much-loved two-story, two-bedroom home in central London provided. Priced out of three-bedroom properties in their neighborhood of Stoke Newington, they called on Bradley Van Der Straeten Architecture to expand their existing home. However, after receiving two planning refusals for a single-story loft extension because it would project above the highest point of the existing roofline, architect George Bradley realized they would need to get creative.
The clients love the community atmosphere of Stoke Newington and wanted to extend their existing home rather than move. The lead architect for the project, George Bradley, lives on the same housing estate and can see the property from his window.
"We decided to approach the design as an interlocking jigsaw," says Bradley. "We built an unconventional, half-height roof extension and reworked the interior volumes to interlock two floors in the space of one-and-a-half floors and create enough space for the additional bedroom. We may have given less footprint, but we created more volume and an additional bedroom by using the space creatively."
A section of Two and a Half Storey House by Bradley Van Der Straeten Architects illustrating how the extension doesn’t exceed the highest point of the existing roof, shown as a dotted line.
BVDS Architecture didn’t do any work to the exterior, apart from the box dormer which is clad in tiles to meet permitted development requirements. "From the outside, I think some people would regard the extension as a mistake, as it defies logic to build something that is only half a floor high," says architect George Bradley.
The solution to fitting two levels into the allowable space? Allowing the ceiling of the first-floor bedroom to protrude upward, forming a bed platform for the bedroom above. This would give the small bedroom below enough head height.
Although the loft bedroom is contained in a half-height extension, it still feels spacious and light. The bed sits atop a platform that accommodates the head height of the room below.
By integrating the bed frame into the fabric of the design, space was also freed up for communal circulation spaces. "The loft extension is half the height it should be," says Bradley. "This triggered a very unique design for the interior, which is worthy of featuring in a Being John Malkovich sequel."
An exposed ceiling allows for the maximum height to be achieved in the limited space. The consistent use of plywood throughout also makes the complex space feel more cohesive and expansive.
It was integral to the success of the project that every millimeter of head height was considered to avoid the interior feeling small and cramped. The roof, for example, uses 30-millimeter vacuum insulation panels to save height. The level of insulation has also resulted in lowering energy consumption for heating the interior, which previously had no roof insulation and so was quite cold.
The stair leads to a small communal landing on the loft level that opens to the new bedroom. "The communal living spaces are a really important part of the design, and it would have been easy to try and cram in more bedroom space," says the client, Andrew. "Instead, the main hallway that BVDS drew at the core of the house is a real triumph in our view."
"We also made the stair space double-height to bring a lot of light into the heart of the house and make it feel as spacious as possible," says Bradley. "It was quite a generous thing to do with the limited space available, but has paid off by not making it feel like an extra bedroom has been squeezed into the space."
A roof window positioned above the double-height stair fills the space with natural light, which reflects off the light-colored birch plywood.
From the entrance, the plywood staircase—which also conceals abundant storage—leads up to the first floor with direct access to the bathroom. From here, it wraps around the double-height space to a small landing lined with bookshelves that leads to the loft bedroom.
A roof window in the loft bedroom is located seamlessly next to the wall to allow light to bounce directly off a surface. "It’s a bit like the effect of an infinity pool," says Bradley. "Instead of water, it's sky, and instead of being on the horizontal plane, it’s on the vertical."
"When you enter the home, the first surprise comes when you reach the top of the first flight of stairs," says Bradley. "You can see the window into the new loft bedroom, and your eye line is already higher than the floor level. I’m sure that must confuse people when they are first visiting."
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An internal window in the loft bedroom overlooks this central circulation space. It shows how the two levels are carefully intertwined and makes the space feel more expansive.
High-quality, FSC 18-millimeter birch plywood boards were used for the majority of the construction, unifying the new and old spaces. The timber cladding also helps to conceal an abundance of clever storage spaces. "We used plywood to demarcate the new versus the old," says Bradley. "We wanted the renovation to feel like an installation that you can journey to and around. It definitely creates a very relaxing atmosphere as the surface has texture and pattern, but is also very smooth to the touch."
It was necessary to step the floor in the loft bedroom up to provide head height for the new hallway on the first floor. This provided the perfect space for the toy shelves and the wardrobe.
"One of the main surprises in this project was how much we love the plywood," says the client, Andrew. "Plywood is a very warm material, and you don’t see it used in such volumes on typical projects. We love how warm it makes the house feel."
To make space for the new hallway, the existing master bedroom had to be reduced in size. To make efficient use of the smaller space, BVDS Architecture designed fitted wardrobes either side and over the double bed. An existing flat ceiling was also removed to open up the space and create more volume.
The master bedroom has an ensuite, which was updated during the renovation. The pale green tiles are Dandelion by Swedish designers Claesson Koivisto Rune for Marrakech Design.
The nature of the interlocking levels meant there were a number of spaces that were unusable as living areas due to restricted head height. These lent themselves perfectly to being used as storage space.
The birch plywood panelling was made off-site by the manufacturer and assembled by the builders on-site. The visual continuity of the single material makes the restricted-height storage areas appear full-height.
The area beneath the loft bedroom, for example, is accessible as wardrobe and storage space from both the small first floor bedroom and the hallway. Although these storage spaces are only 1.6 meters high, they appear to be full-height thanks to the plywood cladding.
Drawing of loft bedroom at Two and a Half Storey House by Bradley Van Der Straeten Architects.
Drawing of loft bedroom at Two and a Half Storey House by Bradley Van Der Straeten Architects.
"The design process felt like being given a puzzle, and the satisfaction of solving it was the same as you get with those games," says Bradley. "We achieved enough ceiling height for two rooms stacked above each other in a quarter less of the height that would usually be required, whilst also making it feel spacious. We did this with lots of careful setting out, a strong overriding concept of a consistent material, carefully placed roof windows, and smart volumetric layout. Each and every part of the design is intertwined—that’s part of its success."
The entry of the home leads to a fully open-plan living/dining/kitchen space with full width sliding doors that open to the garden. This part of the home was completed by the owners prior to adding the extension.
"It’s a really easy family house to live in, and we love being able to see our eldest son playing in his room using the hallway window," says Andrew. "Considering the limited amount of ‘actual’ floor space we have added, the feeling of space is incredible. Every corner of the house has been considered and thought through to make living easier."
A section of Two and a Half Storey House by Bradley Van Der Straeten Architects showing how the half-height extension fits into the home.
First floor plan of Two and a Half Storey House by Bradley Van Der Straeten Architects.
Loft floor plan of Two and a Half Storey House by Bradley Van Der Straeten Architects.
Related Reading:
A London Terrace House’s Extension Goes Graphic With Pattern and Color
Before & After: A Cramped Victorian in London Lightens Up With a Double-Height Renovation
Project Credits:
Architect of Record: Bradley Van Der Straeten Architects / @bvdsarchitects
Builder: Gregos Builders and Decorators Ltd
Structural Engineer: Constant SD
Interior Design: Bradley Van Der Straeten Architects
Photography: French+Tye
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