Perimeter edge strip for separating materials from one another. Fitted along walls and rising elements before a screed, stabilised sand or concrete is poured, it keeps the poured layer clear of the adjoining surfaces — screed from the wall, stabilised sand from concrete, drainage channels from concrete, and so on. This decoupling absorbs the thermal expansion and shrinkage of the floor, prevents cracks and eliminates sound and cold bridges between the floor and the surrounding structure. Made of compressible polyethylene foam.