The house is designed on ecologically sustainable principles. To the north side, an unheated 'buffer' space is enclosed by a curved cob wall, while the south side is glazed to maximise natural daylight and passive solar gain. Elsewhere, the house is largely of timberframe construction; the timber stud walls and the composite timber Masonite roof joists are infilled with Warmcell recycled paper insulation. The roof is covered with a non-PVC singlelayer membrane.
Cob was chosen for its relatively good thermal insulation values and virtually zero embodied-energy costs compared with rammed earth.
The cob wall, approximately 750mm thick, was made of local earth dug from the site, a mixture of fine sand and gravel, together with a small percentage of imported clay, bound with straw. The resulting mix, high in silty and clayey fines, gives suitable compressive strength, minimal shrinkage, crack control and erosion resistance. The wall is self-supporting and rests on a plinth of local Forest of Dean stone with a dense concrete masonry blockwork core. A coping of sinusoidal mill-finish aluminium panels protects the top and throws water away from the base. The coping is raised above a lead flashing on sw battens that are fixed to the cob with 760mm-deep steel pins. At its junction with the roof structure, the flashing has an edge upstand through which air can pass into the space between the roof firrings and battens.
The glazed wall on the south side has a fixed overhang at the eaves formed of tapered sprockets fixed back to an eaves beam. It is extended by tapered steel supports bolted between the sprockets and threaded with wires. They support vines that provide seasonal shading.