CA flow screeds must be abraded, vacuumed and, as with all calcium sulphate substrates, primed with ASO-Unigrund. The moisture content of a calcium sulphate screed must be determined with a carbide hygrometer before installing finishes. If ceramic tiles are to be laid on calcium sulphate screeds with higher levels of moisture than those given in current regulatory works, a max of 1.5% for unheated screeds and 1.0% for heated screeds can be accepted. In this case the floor finish to be installed must have a minimum of 2% joint content (tile 40/40, joint width 4 mm), which may be less with vapour permeable tiles.
NOTE: Exclude moisture rising from the substrate. This type of installation does not conform to recognised technical regulations and is to be contractually declared separately.