Overview of different screed constructions

Screed constructions are among the most stressed components of a building. Depending on the requirements for certain properties, different floor build-ups are used. These are regulated and also described in detail in national standards (for ex. DIN 18560). The screed material, i.e. the screed mortar, is regulated in EN 13813 and is subject to CE marking.

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Bonded screed

The substrate must be sufficiently solid, rough on the surface, free of grease, free of cracks, dry and clean. Generally, a bonding layer compatible with the mortar system must be used. The nominal screed thickness is > 30 mm.
Screed on separating layer

Lay a separating layer or a water vapour permissive polyethylene-coated natron kraft paper in accordance with national standards (for ex. DIN 18560 part 4). Remove coarse impurities in advance. Foam strips of > 8 mm thickness with self-bonding foil must be installed around all rising building parts. The nominal screed thickness is ≥ 30 mm.
Screed on insulation layer

If impact sound and thermal insulation is required, only lay approved materials on the existing substrate. Cover the insulation boards with the tightest possible separating layer. Foam strips of > 8 mm thickness with self-bonding foil must be installed around all rising building parts. The required nominal thicknesses of screed can be found in national standards (for ex. DIN 18560 part 2).
Screed on underfloor heating

All types of construction with a maximum system temperature of 55 °C are suitable. A foam strip allowing movements of ≥ 5 mm must be installed around all rising building parts. In the case of floating constructions, the screed must be poured in two layers. The minimum pipe cover is 40 mm (according to DIN 18560, part 2).
Screed on raised floors

weber.floor screeds can be used on all common raised floor systems. The installation thickness is to be determined according to the specific system. All walls and upstands (pillars, columns, pipe penetrations etc.) must be separated from the whole floor construction with a foam strip of > 8 mm thickness.
Types of floor heating

1. Type A: this type is the most frequently used type of underfloor heating. The heating pipes are fixed directly to the insulation and covered with a screed mortar.
2. Type B: this type is related with heating pipes situated inside the insulation layer. Very often, heat-conducting metal plates are part of these systems. The plates ensure a better heat distribution over the surface.
3. Type C heating screeds: they are usually used in commercial areas with higher traffic loads. The heating pipes are laid within a levelling screed mortar and then covered with a screed on a separating layer for the purpose of load distribution.