The Haven at Horning on the Norfolk Broads is an early, unusual use of Accoya®. The house is surrounded on three sides by water judged to be ‘Flood Zone 3’ (an area most likely to flood). A designation that would normally preclude any development, but discussions with the Broads Authority and the Environment Agency resulted in the architects’ design solution being accepted and planning permission granted.
The challenge of rising water levels was met here by raising the house on stilts, a semi-disguised structural solution that gives the impression of the two-storey building floating over the landscape. In addition, the level of moisture content in the atmosphere in this part of the world is high and generally constant, conditions that demand the use of highly durable and dimensionally stable materials. As a result, Accoya products were specified. Seeking high levels of airtightness and thermal performance, the architects chose prefabricated timber frame closed panels.
Due to the restricted road access into the site most materilas had to be delivered by river barge.
Curved Accoya® glulam beams screen the rear of the house and enclose the building’s circulation ramp and wrap over the rectilinear box that contains the living accommodation. In their support of the roof, these elements allude to the timber ribs that form the skeleton of traditionally-built boats.
Accoya® cladding boards are fixed horizontally to all four sides of the boathouse and to the accommodation pavilion, but it is the fabrication of the curved glulam that is most remarkable here: the bulk of early external uses of modified timber were limited to cladding and decking, but the design and specification of the Haven necessitated bespoke laminated elements to be made from acetylated wood.
The Accoya® glulam and cladding elements were both hand-finished with WoodGuard Color Professional, a protective, merbau-coloured coating that penetrates all the wood fibres without altering the material’s structure and natural appearance. The primary reasons for its use on the Haven are its water-repellant properties, its very high UV resistance and its ability to slow the visible ageing of the wood. The final result is a house that in its design, fabrication and construction is very much of its place but not of its time: the architects of the Haven were surely prescient in anticipating the advanced technical developments in Accoya®-based products that are increasingly being seen in mainstream use.
The Modern Timber House in the UK, chapter 4
Take a closer look at modified wood.
Find out how to specify modified wood.
Images: Richard Osborne