Celotex CW4000 is an insulation board aimed at partial fill cavity wall applications. It comprises a polyisocyanurate rigid foam insulation core, with a thermal conductivity of 0.022 W/mK and low emissivity aluminium foil facings on both sides. CW4000 is manufactured from rigid PIR using a blend of blowing agents that have zero ozone depletion potential and low global warming potential. It has an excellent thermal performance that decreases the thickness of insulation required to hit the required U-value, optimising space in the construction design and helping to reduce the heating and cooling costs within the building.