03 Jul 2015

Secret vault


Innovative use of vaulted ceilings and clever glazing has transformed an urban infill site into a four-bedroom family home.


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Architectural practice vPPR has demonstrated how a difficult, overlooked urban space can be transformed into a fully functioning family home. The Hammersmith, London plot was an unattractive infill site – previously a diesel contaminated taxi garage – surrounded by 11 party walls and overlooked by 24 surrounding properties.

Although the plot is greatly overlooked, it has the advantage of being sheltered from the road by the surrounding residential gardens. Several of the 24 neighbours included active members of the Brackenbury Residents’ Association. Detailed residents’ consultations and the incorporation of their feedback into the design led to seven letters of support for the scheme at planning.

Innovative structure

The domestic design overcomes the issues of privacy and wall space for windows with a unique roofing solution. The design involved seven pyramids of varying sizes with a vaulted roof light in each section. The site is a former taxi garage and was designated as contaminated land. All 1.5m of excavated soil had to be tested and carefully disposed of. The garden walls are underpinned rather than demolished. A steel and timber frame spans off the existing walls to create the roof and floor structure. The roof is constructed from plywood over timber joists, covered with insulation and single-ply membrane.

The geometry of the roof appears simple but is in fact incredibly complicated. It was modeled in 3D software, which enabled precise back and forth between consultants to ensure that the huge steel beams were completely hidden in the crisp angled finishes inside and by the roof finishes outside.

Due to the complex pyramid design, a neat finish around the edges was crucial. The mechanically fixed Sika-Trocal S system proved to be the optimum roofing solution, with a specialist team of up to three applicators working on the project over a period of five weeks.

Single ply, flat roofing expert Sika-Trocal were contracted by Ithaco Roofing to supply the bespoke system. Sika-Trocal comments: “To enhance the architects’ design and emphasise the pyramid shape of the roof, we supplied the Type S membrane in light grey and slate grey. With aesthetics an important consideration for the complex pyramid design, the specification of Trocal Metal helped to reduce overlaps and provide a neat finish around the edges.

“Each triangular section of the roof relied upon precise use of Trocal discs to ensure a uniform spacing pattern, this was key to help achieve a smooth appearance. Careful mitering was required along the numerous edges of each pyramid, the abutments, upstands and the base of the roof.

“To further complicate the installation, all gutters fell at different angles so each section of Trocal Metal was ordered and numbered to ensure it was used for the correct slope. All gutter metals required fixing in a particular method to ensure a slight fall for drainage. Upon completion of the pyramid base detail, the correct colour membrane was laid with matching straps and corners, and lapped over or under depending on which face of the pyramid was being covered.”

The vaulted roofs are covered with two tones of single-ply roofing membrane to produce a harlequin pattern, breaking up the large area of roof and greatly improving the outlook, which was previously onto rotten asphalt roofs. Inside the house, the vaults meet at sharp plastered edges, concealing the down-stand beams rather than expressing them.

Each roof pyramid has been deliberately positioned to throw light into different areas of the property, moving around according to the shifting angles of the sun – the morning light floods into the kitchen, courtyard and breakfast areas, while the evening sun illuminates the dining and library areas.

Clever solutions

Large courtyards bring light into the bedrooms on the lower-ground floor. The roofs are covered in a striking chequered pattern of single-ply membrane.

Vault-like geometry is repeated obsessively at each scale of the design, forming sculptural chamfered edges to the windows, fireplace and TV wall. The timber floors are laid in a cross pattern that reflects the vaults above them.

A double-height den has access to the garden at the back for the homeowner’s young children to play in. A separate study provides acoustic privacy with a view through to the living space. A big double-sliding pocket door opens up completely, turning the dining room into a loggia in the summer.

A mechanical heat exchange system and thick insulation make for an energy efficient home. A study allows for working from home or can become a spare bedroom for visiting relatives. The entrance is stepped up to meet flood requirements but these are wide and gentle for ease of access.

Recognised success

vPPR Architects recently won the RIBA London Emerging Architect of the Year Award for this project, named Vaulted House.

The RIBA London Award Jury comment: “This house is a sophisticated example of urban infill bursting with clever details, its collection of roofs powerfully articulating the relationship between dwelling, light and sky.”

Ivo Hesmondhalgh, Managing Director of Londonwide Properties PLC, adds: “We have worked with vPPR for several years. They have designed one spectacular house for us and are in the process of designing another. Their sensitive appreciation of the possibilities and limitations of a site combined enable them to maximise the potential for any site. Whilst their aesthetic is extremely contemporary, they design houses that it would be a pleasure to live in rather than just admire as an uncomfortable work of art. I wouldn’t hesitate to recommend them.”

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