The new public areas of the two storey visitor centre include a reception area at first floor level, an exhibition hall and a double storey height restaurant. A steel-framed structure spans these large spaces. The primary link between floors is a cast in-situ concrete ramp; part of the west wall is 'pulled out' to contain the ramp, and windows within it give selected views over the wetlands.
The materials and construction of the centre reflect the architect and client's concern with ecological issues. The external envelope is insulated with 150mm thick mineral fibre insulation to reduce energy consumption, and clad with relatively natural, organic, low-maintenance materials; ventilated external walls of untreated Western red cedar boarding, roofs of cedar shingles or terne coated stainless steel.
The cedar shingle roof to the extended west wall drains into a 450mm wide terne-coated stainless steel gutter cantilevered from the main structure. The width accommodates heavy local rainfall, protects the walls below from bird droppings and allows the gutter to be walked on for maintenance.
Horizontal and vertical t & g cedar wall cladding, fixed to battens, acts as a rainscreen to a ventilated and insulated inner skin, formed of a steel RHS frame and purlins clad with plywood.
Thermally broken timber window frames are set virtually flush with the cladding to prevent birds landing on the sills. A trim of terne-coated stainless steel wraps round the jambs and head of each window and forms drips between the frame and the cedar cladding. Paired windows are defined by 50 x 50mm cedar posts. Deep maple reveals are formed with a shadow-gap detail.