When it's not dry enough, there are steps you can take - either wait; force dry (calcium sulphate-based floor screeds only); or apply a surface DPM.
Unlike cement-based screed, calcium sulphate screed can be forced-dried, by commissioning the underfloor heating system (if applicable) or by utilizing a dehumidifier.
Five days after installation of the screed, the commissioning process starts with a water temperature (UFH manifold) of 25°C, which is maintained for three days. The water temperature is then raised to the maximum value (max 55°C) and kept at this level for at least four days.
Allow for plenty of ventilation by opening windows on each side of the building. Please note: it is essential that the building receives sufficient air changes in order to achieve low air humidity (< 65% RH).
Five days after the installation of screed, introduce heat and utilize a dehumidifier with correct capacity for the area of the building. Use several dehumidifiers if required.
Keep windows and doors closed to allow the dehumidifier to work efficiently.
Continue with the above procedure until a moisture content of 0.5% (tiling/ vinyl) or 1% (carpet) is achieved.