This pavilion is open fronted, its three other walls demonstrating three different unfiredearth constructions. (These walls don't meet at the pavilion corners, providing a challenge for the engineer. ) The cob (earth and straw) block wall (U = 0.23W/m 2K with external insulation) uses earth from within 10 miles.
Blocks are hairy (which is good for keying plaster), part left exposed for demonstration, part finished with an earth plaster reinforced with llama hair, with a polished wax finish.
The cob wall (U = 0.21W/m 2K with external insulation) was built up in lifts of around 800mm without shuttering, by forking on the mix and treading it, then trimming the 500mm-thick wall as it dried, a process which can produce relatively sharp arrises.
This has been left exposed. The work was done between the main contractor and artists Jackie Abbey and Jill Smallcombe (whose work includes the cob bus shelters at the Eden project). Here the earth was subsoil from the foundations plus straw and a sharp sand. The third wall is rammed earth (U = 0.23W/m 2K with external insulation) formed within steel shutters, without straw and a drier mix. It has been finished with linseed oil. The contractor had to wait for some differential shrinkage before trimming the three walls to height for building the roof.
Roof insulation is a recycled cotton quilt - blue from its content of denim, imported from the US, but expected to be available shortly from Sheffield Insulations. The construction is a cold roof and there are slots on the parapet on two sides to ventilate the roof construction. Roof finish is a 'brown roof ' comprising 6.5 tonnes of building rubble, a poor growing medium but one that tends to lead to greater species diversity in time.