75mm timber frame with wood/hemp fibre insulation with 40mm UdiSPEED board to cover. 6mm layer of Udi plaster to go over board. U-Values 0.312 with 40mm board or 0.274 with 60mm board.
Material cost per m2 -
Natural Fibre Insulation - £6.24 per sq.m
Timber Studs - £1.25 sq.m.
UdiSPEED 40mm - £14.05 per sq.m.
UdiSPEED 60mm - £17.71 per sq.m.
Plaster - £10.02 per sq.m.
Reinforcing mesh - £1.60 per sq.m.
Fixings £2.40 per sq.m.
Total = £35.56 - 40mm
or £39.22 for 60mm