Screed is not a leveling material — this is the most common misconception leading to incorrect material selection. Screed is a structural floor base layer: thick, load-bearing, with a long curing time. Leveling compounds are thin, non-load-bearing, and can be covered quickly. Their functions, thicknesses, and curing times are completely different.
The purpose of screed is to:
Screed is load-bearing — it must distribute the load together with the substrate. It fails by cracking or delaminating if it is not properly bonded to the substrate or if it is loaded during the curing period.
Screed is typically applied in layer thicknesses of 30–80 mm. Below 30 mm, screed is brittle and does not provide adequate load distribution. Over underfloor heating, a minimum coverage thickness of 30–35 mm above the pipe is required for even heat distribution. Fiber-reinforced versions can be used above 50 mm, but expansion joint design is mandatory in this case as well.
Screed requires 28 days to reach full load-bearing capacity. This is not a recommendation but a chemical process: the cement curing process fully completes in this time. Installing the floor covering before 28 days means the screed underneath is still curing — which leads to cracking, movement, and eventually tile delamination.
For underfloor heating systems, a minimum of 28 days must pass after screed installation before the first heating, and the heating must be gradually increased according to manufacturer instructions, starting from a low temperature.
Expansion edge strips must be installed along walls and, depending on the room size, field expansion joints must be created in all screeds. The edge strip absorbs dimensional changes caused by thermal expansion of the screed. Omitting it causes the screed to press against the walls and crack at the weakest point.
Fiber-reinforced screed contains reinforcing fibers made of polypropylene or steel, evenly distributed. This increases resistance to cracking and reduces the risk of shrinkage cracks. For underfloor heating systems and layer thicknesses above 50 mm, the fiber-reinforced version is strongly recommended.
Browse our screeds or request advice for selecting the materials and layer structure needed for your floor construction.
The Kerakoll Color Collection is an integrated project that includes innovative materials - resin, cement, handcrafted wood, microcoatings, paints, and glazes - coordinated on a single color palette.
