RIBA Downland Prize for Architects
Commended
Unique 'floating' glass stair, spiral roof attracts judges
Andrew
Dyke, Cresswell Cuttle & Dyke Ltd, Petit Bouet, St Peter Port was
commended For L'Escargot, Forest, Guernsey
'Probably the most unusual house on the island of Guernsey' is how architect
Andrew Dyke describes L'Escargot, which is free-form spiral in plan and
reminiscent of a snail's shell. The house is tucked into the rocky hillside,
with soft landscaping at the front.
Because the site slopes steeply, the main entrance and living space is
on the upper floor level. Above this is a study area, reached by a dramatic
glass staircase which is designed to appear to float up the surface of
the wall. The impression is emphasised by the lack of outer string: the
handrail is fixed to only the wall side. As the staircase only accesses
the study area, which is not deemed to be a habitable room, it avoids
normal staircase requirements.
The staircase is formed from solid glass treads, 75mm thick with a non-slip
upper surface. Each tread is tapered and set in resin in a stainless steel
box which is set into the curved reinforced concrete wall.
Andrew Dyke says that it was extremely difficult to source the treads,
eventually supplied by specialists Ozone Glass. 'Although the staircase
is essentially a sculpture, it is very solid and secure and perfectly
practical for everyday use.'
The curved slate roof follows the spiral form, winding up to its apex
over the centre of the house. The roof structure comprises radiating timber
rafters, with plywood sarking, felt, battens and a marine plywood outer
skin to which the slates are directly nailed. Because the roof is curved
in two dimensions and slates have to be laid at right-angles to the fall
line, the setting out for each row of slates had to be carefully marked
in chalk on the plywood before the slates were nailed. The diminishing
courses resulted in some very small slates near the top of the roof. The
chimney is an unusual boat shape with a sloping top which accommodates
and complements the curve of the roof.
Setting out the curved walls was difficult, as was 'unwinding' the curved
external wall elevation to ensure an even slope to the eaves. The precise
dimensions for the height and position of the sloping and curved wall-plate
were calculated using a 3-D computer model.
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