FIRST THIN
Unmanaged excess subfloor moisture is the leading cause of floor failure and frequently resu F. Ball advises on how dealing with this problem should be approached when working ov
Unchecked subfloor moisture, whether residual construction moisture or rising damp, can attack flooring adhesives and damage floorcoverings. It can also promote mould and bacterial growth. Not only can this ruin the finished appearance of a flooring installation, but it can potentially cause complete floor failure and present a health hazard. The breakdown of adhesives as a result of contact with moisture can also cause increased VOC emissions in indoor environments. To prevent this, it is important to deal with excess subfloor moisture appropriately prior to installing floorcoverings.
TESTING F. Ball recommends that a moisture test is undertaken as part of any flooring installation, having first prepared the subfloor so that it is suitably smooth, sound and free of contaminants. If the subfloor Relative Humidity (RH) levels exceed 75% (65% if wood floorcoverings are to be installed), a moisture management solution will be required to prevent excess subfloor moisture attacking adhesives and damaging floorcoverings.
The only method of measuring subfloor relative humidity levels with certainty, and the method advocated by British Standards, is to use a calibrated hygrometer.
18 | SCREEDS, RESINS & COATINGS
WATERPROOF SURFACE MEMBRANES The application of a waterproof surface membrane is the usual solution for effectively controlling damp (unless it’s a calcium sulphate screed). The best-performing epoxy waterproof surface membranes will isolate excess subfloor moisture where relative humidity values are up to 98%, with a single coat application, which will fully cure in as little as three hours.
“If the subfloor Relative Humidity (RH) levels exceed 75% (65% if wood flooring is to be installed), a moisture management solution will be required.”
Quicker, two-coat systems are also available, such as F. Ball and Co. Ltd.’s Stopgap F78, that will create an effective
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