Timber was the natural choice of material for the structure, cladding and principal elements of the Fishing Hut, its barn-like form echoing the local vernacular of timber agricultural buildings.
The exposed timber structure, shutters and cladding are made of oak, chosen for its durability and characteristic colour and grain. It is untreated and will weather to match the silver-grey colour of the roof covering and the steel supports which emerge from the water.
The building rests on pad foundations which were set on the lake bed and consist of precast concrete drainage rings filled with concrete. Rising from them, nine galvanized steel goalpost frames support the timber floor structure and timber frame superstructure – a series of oak glulam columns and beams which form 10 bays at 1.8m centres. These columns support simple oak glulam trusses and the beams project at the eaves.
Both architect and structural engineer felt that the use of flitch plates and visible bolts or pellets to connect oak glulam members would be inappropriate in such a finely crafted building. Instead, the main structural connections are by direct bearing; the top of each column is notched to slot into a rebate in the beam above. Each connection is fixed diagonally by high-tensile screws and concealed by being fixed from above. Horizontal roof truss members prevent roof spread and avoid the need for a ridge beam. Insulated softwood rafters form the roof, clad internally with 15mm-thick finger-jointed oak boards and externally with profiled aluminium sheet on larch battens.
Glulam to order
External walls of sliding glazed screens and slatted oak shutters are fixed between the oak glulam columns and beams. Pivoting upwards from the eaves to lie parallel with the projecting oak beams, the shutters transform the interior to an outside space and act as large horizontal brise-soleils.
To fabricate the structure, the architect approached Inwood Developments of Lewes, one of the few UK companies to produce oak and hardwood glue-laminated components to order. Inwood developed the timber process and fabrication details with the architect and became general contractor, sub-contractor and specialist supplier, manufacturing and prefabricating most of the building elements apart from electric installation, plumbing and steelwork.
Beams and columns were glue-laminated in the Inwood factory from 22mm kiln-dried and graded PEFC-certified European oak from France. Glulam components in the kitchen area were of FSC certified Douglas fir sourced from southern England.
Tenoned and jointed oak is used for the glazed screens; the shutters are of vertical oak boards spaced apart on an oak frame with connections and actuators of stainless steel to avoid bi-metallic corrosion. Inwood prefabricated all the elements individually in its factory before installing them on site and sealing them with a UV-protection oil.
Minimum impact
With the site having significant ecological importance – it is an SSSI (Special Site of Scientific Interest) and SAC (Special Area of Conservation) – protection of this environment was the prime factor in design and construction. To prevent environmental damage on site, the team used prefabrication and dry construction techniques as far as possible to minimise on-site processing of materials and avoid pollution risks. It built the superstructure without draining the lake to avoid damage to flora and fauna. Materials were carefully selected to ensure that run-off and components in contact with the water would have no adverse impact on the aquatic environment. The building sits over the lake and rainwater discharges directly into it. Wastewater is treated on site and cleaned before discharge directly to the river. The building’s floor is raised above predicted flood levels.
Another important part of the design process was the impact of materials on the wider environment. The inherent durability of each specific component was chosen to maximise life expectancy, limit maintenance and minimise embodied energy. Most of the structure is built of oak, an indigenous and sustainably sourced hardwood whose natural durability allows the construction to be untreated externally. The glue-laminated structure uses small timber sections that make efficient use of the raw material. Extensive use of prefabrication minimises site waste and the transportation of bulk materials, while energy efficient LED lighting helps keep energy consumption to a minimum.
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