The screed is an invisible but decisive layer in the floor structure. It lies between the structural slab (often with insulation and a separating layer) and the visible covering such as parquet, tiles or vinyl. Its job is to create a load-bearing, level and dimensionally accurate surface on which the covering can be laid cleanly. In most residential buildings the underfloor heating is also embedded in the screed.
There are mainly two construction methods. The classic cement screed is placed as an earth-moist mass, levelled off and smoothed – it is robust and inexpensive but takes a long time to dry out. Flowing screed (usually anhydrite/calcium sulphate based) is poured in liquid, levels itself almost automatically and produces a very even surface; it encases heating pipes particularly well and is ready for covering sooner.
The process: after laying insulation, edge insulation strips and – if present – heating pipes, the screed is placed in the planned thickness (typically 6 to 8 cm for cement, thinner for flowing screed) and levelled. This is followed by the crucial drying and curing phase. As a rough rule of thumb, cement screed needs about one week per centimetre of thickness, flowing screed considerably less. Only when the residual moisture is low enough may the covering be laid – otherwise damage may occur later.
Screed is needed in every new build and in larger renovations with a new floor structure. For pure covering changes, a levelling layer or a thin filler coat is often enough instead of a completely new screed.
Costs for flowing screed in Switzerland are usually around CHF 30 to 50 per m² (approx. 4.5 cm); for a complete subfloor including insulation and installation, more like CHF 50 to 100 per m² depending on structure and thickness (guide values, no guarantee).