Earthwool Dritherm Cavity Slabs are semi-rigid or rigid slabs manufactured from non-combustible, water repellent glass mineral wool. They are manufactured 455mm wide to suit standard vertical wall tie spacings ensuring a closed joint with adjacent slabs. Earthwool Dritherm Cavity Slabs are designed for the thermal insulation of masonry cavity walls and are installed to full fill the cavity. Earthwool Dritherm Cavity Slabs represent no known threat to the environment and have zero Ozone Depletion Potential and zero Global Warming Potential.