Substrate Moisture Content
Permissible substrate moisture content without underfloor heating
| For cement screeds | <6 % CM |
| For anhydrite screeds | <0.5 % CM |
| For magnetite flooring | 3–12 % CM (depending on the organic content) |
Permissible substrate moisture content for use with underfloor heating
| For cement screeds | <6 % CM |
| For anhydrite screeds | <0.3 % |
| For magnetite flooring | 3–12 % CM (depending on the organic content) |
To check the moisture content, use the “Rubber Mat Test”, according to ASTM. A polyethylene sheet of > 1x1 m in dimension shall be taped to the concrete surface. Leave the polyethylene sheet in place for > 24 hours prior to testing. This test allows for the detection of any condensed vapour transmissions.
Note: CM: carbid method, to determine the moisture content of the substrate. For all moisture contents, the quality of the substrates and surfaces, always follow the guidelines of the wood flooring manufacturer.