Specifier's choice: Pete Sutton's house, Highbury
In the late 1980s, Pete Sutton bought a double-fronted end-of-terrace house. Adjacent was a wide, shared right of way between his house and the two-storey post-war factory along the road, which had replaced three or four bombed terrace houses. The factory site was sold in the 1980s boom but it was difficult to develop. Eventually a housing association bought the site and planned to build a three-storey housing block to replace the old factory and houses in the backland.
Sutton and the housing association negotiated a settlement in which he gave a right of way to the backland and gained a strip of land at the side of his house (enough to park a car) and a new, splendid, high brick wall to mark the boundary between the two.
During the next five years, Sutton played around with ideas for the plot and eventually came to the conclusion that the most interesting thing to do was to build a small separate house on the site. Islington planners were not too keen on the idea, despite the fact that they had approved Chance de Silva's Cargo Fleet ('Specifier's Choice', AJ Focus, April 2004) a mile away near Arsenal Football Club. But, following much negotiation, the lay planning committee approved Sutton's scheme, one member reportedly saying (approvingly), 'this is almost a good piece of modern architecture'.
End of terrace The building footprint is approximately 9m x 4m, set back on the building line around 2m from the street. At the back, the high wall cranks inwards, enclosing a triangle of garden that will eventually be decked. The house is on three levels. There is a ground-floor living room/kitchen with a WC under the stairs, and the now-mandatory disabled access to the front door. The first floor has a bathroom at the front and a bedroom at the back, with the top floor offering a large, open studio that could be converted into two bedrooms.
The setting for Sutton's house is an existing Victorian terrace built with London stocks, and with the usual bay windows and mouldings. In this section of the street, it is two-storied, although the housing association's flats along the road have three storeys.
The access gap, now a proper entrance with its tall iron gates, means that Sutton's house visibly terminates a significant section of the terrace. It seemed reasonable to mark this with a slightly higher roofline and to separate the new from the old visually. Sutton had emphasised this separation on the street elevation with a vertical glass strip down the old-new junction, and by using deep, oversailing eaves to differentiate his new building from the adjacent, old, centre-valley roofs hidden by continuous parapets. Sutton's elevations are rendered white with blue window and door trims. He had originally wanted blue rendering but the planners made it a condition that he used any colour other than blue, but declined to actually insist on white.
Sutton got fed up and said: 'Sod it. OK, it'll be white.'
Firm foundation The housing association's eight-year-old boundary wall is 2.4m high, with enormous strip footings. Sutton's old house has standard 19th-century London footings - which is to say none. The local foundation is made up ground, and the original idea was to have concrete pad foundations, but the groundwork contractor, Dual Contractors, which Sutton had used on a project for one of the Rolling Stones, reckoned mini-piles were a better idea. The company designed a pattern of ten 200mm-diameter piles, driven around 10m deep. They support a reinforced concrete slab, sitting over 250mm of Cellcore anti-heave underslab, required by National House-Building Council (NHBC) Building Control because of the proximity of two small trees.
The walls are of 215mm Celcon 7N Hi Strength lightweight aerated blocks, sitting on a 300mm reinforced-concrete edge beam.
The front and back facades and the internal cross wall are supported by steel beams sitting on steel columns on the inner side and by the structural flank wall on the outer. A ply diaphragm cross wall at first-floor level was the engineer's suggestion; it helps to stiffen the structure where the front wall, with its strips of unbraced vertical and horizontal glazing, might tend to rotate unacceptably.
In fact, there is a substantial strip of reinforced concrete forming a stiffening edge to the inner side of the glazing strips.
The flat-sloping roof structure is based on a steel ring beam with intermediate 50mm x 200mm timber joists, to which the 18mm WBP ply deck is fixed, forming a kind of diaphragm. The only structural load on the foundation-less party wall is the roof ring beam.
There is a plasterboard wall separating the old house acoustically from the new. Sutton says: 'It was during the crossover from the old acoustic regulations to the new, but the NHBC suggested I should comply with the new. It then decided it was okay to follow the old rules, but I thought following the new rules was a better idea. So there are 50mm x 55mm timber studs resiliently fixed to the party wall with two layers of 12.5mm plasterboard screwed to them.'
Self managing In addition to regular architectural commissions, Sutton has simultaneously been advising on a quite large and complicated self-build scheme he designed in nearby Hackney, and in some ways the experience of one has fed into the other. For his own house he has been architect, project manager, procurement manager and foreman.
'I didn't have a lot of input at the structural stage, but I was quite involved in the roof and generally in the carpentry, ' he says.
'Being project manager involved pricing and ordering things, looking for economical suppliers and, in some cases, doing detail drawings of components such as steelwork, windows and glazing. It's amazing that it all fitted because there were three or four people to go through, and get it wrong, before a detail was actually built. This was especially the case with flashings and gutters, and drawings for other items that had to be prefabricated, such as joinery.' The blue powder-coated aluminium sills, rainwater goods and flashings are from Fabrical of Basildon. 'I had to size these elements before the external insulated render went on, but when it came to it, practically everything fitted, ' says Sutton.
How did the fact that Sutton was also the architect affect the choice of elements? He says: 'I think the approach was to go for durability while keeping a tight hold on price.
So I've gone for a middle range in the spec.
For example, it's not Sto but Weber; the soffit panels are Eternit Lamina and Multiclad when I wanted to use something a bit classier; the windows are not Rationel or Velfac but Blairs of Scotland. Not that there is anything wrong with Blairs, which I have used before on projects. Blairs made sense here because we could use the same glazing sections from the standard catalogue for both fixed glazing and opening windows, and we could get glazing sections [for the vertical strip window and the horizontal strip under the eaves] that were 3m in length.'
Surface treatment The three blockwork elevations are skinned in a Weber Expomesh external-wall insulation system. This involves an initial 80mm layer of expanded polystyrene (eps), a plastic reinforcement mesh through which large circle-headed fixings are nailed to the blockwork. Then the two RCP Plasterers operatives applied a slurry coat, which they keyed. Following that, four skilled plasterers left Bognor Regis at 4am one morning, arrived at 7am, and worked through the day applying the final coat of the sticky polymer over the three elevations. 'They did it this way because they had to work to a wet edge and that meant doing it all in one go, ' explains Sutton. 'They drove home, in the hope of getting to their pub for last orders.' The roof membrane over the ply deck is Alwitra Evalon V single-ply membrane. Like the Weber system, it was less expensive than the standard, in this case Sarnafil. 'I've used it on other jobs, ' says Sutton. 'I chose singleply because it can accommodate movement and it doesn't crack. This is a warm roof with 350mm of mineral-wool insulation at ceiling level, with a ventilated void above it.
The foil-backed plasterboard ceiling is hung from the joists. It is actually quite a thick roof structure and the narrowness at the eaves is a deliberate illusion.' The small glazed roof at the back is by TW Ide (now Twide Paragon), an old established firm based at Glasshouse Fields, Stepney, in east London. The ground-floor glazed doors below have sidelights. 'I feel now it was a bit timid because there's too much going on in such a small space, ' says Sutton. 'I do wish I'd specified a Scandinavian sliding-door system rather than the casement doors, a big slider by somebody like SWS. It was all money - it would have cost another ú3,000 or ú4,000.' Sutton has inserted glass blocks in the side wall to break up the big, blank surface, and to provide extra light to the interiors, and still comply with the regulations about spread of flame. There is also a group of glass blocks over the front door to allow more light into the hallway.
Interior specification In keeping with the majority of architectural specifiers in this series, the door handles will be D Line, or a cheaper version. Doors are flush and in veneered ash. Stairs, by K&D Joinery, have parana pine stringers with chipboard risers and are going to be faced with a heavy veneer of maple flooring. As Sutton points out, this has to be applied last as damage is inevitable when the stairs are the workmen's main means of access. The floors throughout will be veneered Canadian maple from Reeves Flooring.
The bathroom and kitchen taps will be Vola, with a Bristan shower mixer. Sanitary fittings are mostly by Ideal Standard but include a Studio basin and a white, Chipperfield-designed, back-to-the-wall WC and a Bette doubleended bath. The kitchen will be by Magnet.
Sutton has spent time on maximising the sustainability of this house with Wirsbo underfloor heating. It is a plastic-pipe system buried in the ground floor slab, with tiny radiators on the first and second floors.
'They can be tiny because the energy rating for the whole house is pretty good, despite all the bits of glazing, ' Sutton points out.
'The strategy is that we have good ambient heat, with the screed and slab acting as a heat sink. The walling blocks are lightweight, so they will act as a minor heat sink, and the radiators will give top-up heating on upper levels when it's necessary. The system has two controls, one at ground-floor level for the primary feed from the boiler to the underfloor pipes, and the other control at the top. You need to run gas boilers at full efficiency and the plumber said that there wasn't a combination boiler that was small enough to operate efficiently. So we used a small Ideal Boilers condensing boiler, with a thermal water store in the form of a giant tank that takes up a big cupboard next to the bathroom at first-floor level.' Sutton is installing Cat5 cabling throughout the house, providing broadband and network points in every room for computers and for terrestrial and cable television - and he has installed high-spec cabling for satellite broadcast. Once the cabling runs were disguised by screwed plasterboard, the final skim coats were by the aptly named company Spreadwell.