Glass faced phenolic insulation was chosen for its ease of bonding, low conductivity of 0.021 W/m.K, good compressive strength and resistance to the passage of water vapour.

In a fire, it combines very low flame spread with negligible smoke emission and a very low level of toxic gas emission.

Bonded to wall plaster with Gripfill. Other walls have been bonded with Mapei Keraflex and polyurethane adhesive for comparison (so far no differences have been noted) .