External wall insulation

An external wall insulation system (or EWIS) is a thermally insulated, protective, and decorative exterior cladding procedure involving the use of expanded polystyrene, mineral wool, polyurethane foam or phenolic foam, topped off with a reinforced cement based, mineral or synthetic finish and plaster.

The thickness of thermal insulation is dependent on whatever type is required in order to create a partition with a heat transmission factor of U=0.25-0.3 W/m2K. When calculating the actual insulation requirements, consideration must be given to current Building Regulation standards. Consideration must also be given to exposure and durability, and whether the structure might be subjected to vandalism etc. In many older properties, special attention is required for concrete beams or lintels which act as thermal bridges providing poor insulation.