Clay drybuilding

Clayboard D20 / D25

Drywall clayboards for planking wood and metal post and beam constructions within interior walls, facing, ceiling and roof surfaces. The CLAYTEC clayboard is a drywall board and a clay plaster in one. It was developed based on practical building experience and has been available on the market for 20 years. With a density of 700 kg/m3 it provides a clay mass which is easy to handle.

Field of application
Clayboards for planking indoor wood and metal post and beam constructions. For interior walls, facing, ceiling and roof surfaces in drywall construction. As a substrate for YOSIMA Clay designer plaster or CLAYTEC Clay topcoat fine 06 with CLAYFIX clay paint.

Building clay and loam, perlite, reed matting, hemp, hessian mesh.

Material parameters
Bulk density approx. 700 kg/m3 (thermal conductivity value after measuring the clayboard thickness = 25 mm 0.13 W/mK, Cp approx. 1.45 kJ/kgK (thickness = 20 mm 20.3 kJ/m2K, thickness = 25 mm 25.4 kJ/m2K),µ 18)

Building component values (certificated)
Sound insulation: 36 dB (skirting), 48 dB (dividing wall), 56 dB (dividing wall). Please ask for separate information on fire resistance tests for walls and ceilings.

Dimensions and weights
D20: W = 150.0 cm, L = 62.5 cm, thickness = approx. 20 mm. Weight approx. 13.1 kg/board = approx. 14.0 kg/m2
D25: W = 150.0 cm, L = 62.5 cm, thickness = approx. 25 mm. Weight approx. 16.4 kg/board = approx. 17.5 kg/m2

Supply form
Shrink-wrapped on pallets of 60 units

Moisture stresses arising from plasters and screeds installed when wet are not permitted. The relative humidity during storage and after installation should not generally exceed 70%. Keep the entry of moisture via the plasterwork as low as possible.

The boards are cut with a jigsaw or handheld circular saw. The FESTOOL diamond cutting system DSC-AG 125 Plus-FS is particularly suitable; see also the clip at

Plaster must be applied to the smooth side of the board, not the slightly wavy side. The lowest row of boards must be fitted with a gap to the floor. The panels are abutted against the substructure. The panels are attached to wood using CLAYTEC clayboard screws (5 x 50 mm) or WÜRTH quick assembly screws with coarse thread and 04164 washers. To attach to metal, use WÜRTH quick assembly screws with a drive point and 04164 washers, or KNAUF all-purpose screws (FN 4.3 x 35 mm) with washers. Spacing between screws ≤ 20 cm, i.e. 4 fastening points are required per intersection between panel and substructure (20 screws for each D 20 board, 16 screws for each D 25 board)

Stapling with broad back staples is also possible, e.g. using BEHRENS (BEA) 146/55NR HZ. Twice as many staples should be used compared to screws (see above); spacing from the edge 10-15 mm.

In bathrooms, use rustproof fasteners only.

Cross joints must not be used and horizontal or vertical joints must not be continuations of the borders of wall openings. Install the boards with joints that are offset by 30 cm, or even better, 50-75 cm.

Subsequent processing
If necessary, fill gaps of ≥ 1 mm in width with CLAYTEC clay adhesive and reinforcing mortar or clay topcoat fine 06 and leave to dry. Carefully dust panels; if necessary, moisten slightly before use (with spray).

Thin layer coating: The surfaces are coated with a 3 mm layer of clay adhesive and reinforcing mortar. This can also be sprayed on using a plastering machine; if this application method is used, rest periods are not necessary. Flax or glassfibre meshes are spread flat and worked into the surface while it is still wet. Properly apply YOSIMA Clay designer plaster after drying. Apply the reinforcement layer very carefully for YOSIMA
colour clay surfacer
or CLAYFIX clay paint system (= fill the drill holes and indentations before starting and allow these points to dry); it is more advisable to apply a thin layer of clay topcoat fine 06.

Wall panel heating: Spray on an initial layer of clay undercoat plaster with straw, clay plaster, mineral clay plaster or SanReMo in a layer thickness not exceeding 8 mm. After drying, fill the gaps as far as the pipe clamp for the wall heating. Apply heat to dry the entire basecoat layer. For further instructions, refer to the CLAYTEC clay plasters worksheet.