It’s not often that a judging panel is united in its decision-making. But so overwhelming was the support for the new pool complex at the renowned Hurlingham Club, that there could have only been one overall winner of the 2012 Wood Awards competition. The design and execution of the new timber-based structure was judged to be even more breathtaking in the flesh than its pictures promised – a rarity, according to the judges.
Designed by David Morley Architects, the new pool complex replaces an outdoor pool and changing pavilion which were 80 years old and, though much loved by members for their character and charm, had reached the end of their serviceable design life. The original changing pavilion was a long, single-storey timber framed building with a pitched roof, tiled in grey slate. The building was clad in horizontal timber boards painted in the distinctive Hurlingham blue and white – colours which were beautifully reflected by the adjacent pool.
The new pavilion retains the qualities, and particularly the charm, of the original traditional lido-style buildings while providing high quality, modern, accessible changing facilities with an efficient layout, maximising natural day-lighting. It houses men’s, women’s and family changing rooms, showers, WCs, reception and management offices.
Above the walls, lifted clear by a glazed clerestory, the zinc roof rises and falls in five shallow vaults, like a series of upturned boats, extending at the front of the building to create a shaded canopy terminating with a horizontal fascia. The clerestory gives daylight and views of the tree canopy, while making the changing rooms completely private and reducing the need for artificial light.
The changing rooms have been carefully planned so that their internal cross-walls co-ordinate with structural junctions/bays; at the divisions between changing rooms the clerestory glazing returns and continues over the cross-section to terminate the tops of the internal cross-walls. The clerestory glazing at the rear of the building is a series of opening windows for ventilation.
The five undulating vaults of the roof are formed by a series of prefabricated timber cassettes, which create an elegant structure, uninterrupted by beams or joists. Price and Myers Geometrics and fabricator Commercial Systems International developed an approach that was originally established with David Morley Architects’ residential penthouses at Lister Mills, Bradford.
The cassettes, each 2.25m wide and only 300mm deep, have sides of laminated 18mm OSB/ply with timber I-beam ribs (OSB web and softwood flanges) slotted between them at 400mm centres. They are lined above and below with 18mm structural OSB skins.
Accommodating the curve
The cassettes were bolted together along the length of the changing pavilion; to accommodate the curve at the rear of the plan they vary in length from 11m at the widest point to 3m at the north end.
The five vaults of the roof are each formed of four cassettes. The rise and fall of each vault is created by skewing the top and bottom OSB skins of the cassettes and by gently tapering/angling the timber I-beams inside.
The development of an extremely detailed fully parametric 3D model enabled the complicated geometry of this roof to be plotted and understood – 1,300 profiles detailed the shapes of all the cassette elements. The 3D model was then used directly to cut the required shapes from ply and OSB for factory assembly, allowing tight control over the quality and minimising the installation time on site. The result is an extremely efficient integration of structure with roof form, an uncluttered soffit and an elegant realisation of the original vision.
The cassettes rest on a series of paired timber struts set at the lowest points of the roof vaults. At the front of the building the longer strut branches out to support the edge of the projecting roof; the shorter strut cants towards the inside and is bolted with flitch plates to the sides of the cassettes. The struts are formed of double layers of 24mm birch ply and at their bases are connected by steel flitches to support columns, each formed of a double layer of 18mm ply with a 44mm softwood timber core.
At the rear of the building the ply struts take the form of shorter stubs set between the opening windows; they are supported by wide concrete columns, cast in situ, which run along the rear wall to provide stability.
The frames of the clerestory glazing are neatly concealed in back-to-back stainless steel channels welded to the steel flitch plates, and within recesses created at the edges of the layered ply struts. The soffit of the roof is clad with 6mm birch-faced ply.
The new pool complex is a masterly addition to this famous sporting club; that timber was the principal material proves that the marriage of old and new – with some clever design work – can achieve results that win awards. It’s something that the Hurlingham Club delivers in spades.
