TACKLING DAMP
John Green, one of F. Ball and Co. Ltd.’s technical service officers, advises on a fast-track alternative to waterproof surface membranes for guarding against floor failure resulting from excess subfloor moisture.
Excess subfloor moisture is still the leading cause of floor failure, resulting in major inconvenience and losses for contractors year after year. F. Ball’s technical service department frequently receives calls from contractors who have been called to rectify a recent flooring installation where floorcoverings have begun to lift as a result of unmanaged excess subfloor moisture, and the F. Ball tech reps often attend site visits where this is the case.
To prevent this, contractors should always take the time to determine subfloor moisture levels and deploy an appropriate moisture management solution where necessary.
WATERPROOF SURFACE
MEMBRANES The usual solution for effectively controlling damp is the application of a waterproof surface membrane. Advanced products are now available, such as F. Ball’s Stopgap F77, that 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.
F. Ball’s Stopgap F78 provides an even quicker, two-coat system. The first coat dries in 15-30 minutes, and a further 30 minutes drying time is required for the second coat to create an effective barrier against residual construction moisture where relative humidity values are up to 95%
ANOTHER OPTION There is another solution for creating a barrier between excess subfloor moisture and floors where a fully bonded system is not required; a loose-lay isolator membrane, such as F. Ball’s Stopgap Isolator Membrane, which can be laid directly onto the subfloor, without the requirement for an adhesive.
The membrane has nodules on the underside, creating an airspace to allow water vapour to travel to the edge of a room, into a dry wall or ventilated area, where it can safely
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escape, and a wide range of floorcoverings can be adhered to its upper surface.
This is ideal for where subfloors cannot be prepared in the usual way, such as where screeds are contaminated with oil, grease, other chemicals or old adhesive residues, or simply as a fast-track option where projects need to be completed to tight timescales. Isolator Membrane substitutes for a levelling compound to create a smooth base for the receipt of resilient floorcoverings and carpet tiles, removing the need for mechanical preparation or even removal and replacement of a contaminated screed before the application of a waterproof surface membrane or levelling compound.
It is also a solution for situations where the contractor requires a temporary flooring installation, including heritage settings, such as listed buildings, where the subfloor must be preserved. Stopgap Isolator Membrane allows durable new floors to be installed and easily removed at a later date, enabling buildings to be returned to their original state.
MOISTURE TEST A moisture management solution is required to prevent excess subfloor moisture attacking adhesives and damaging floorcoverings where Relative Humidity (RH) levels in the subfloor exceed 75% (65% if wood floorcoverings are to be installed). For this reason, F. Ball recommends that contractors undertake a moisture test as part of any flooring installation, once it is established that the subfloor is suitably smooth, sound and free of contaminants.
The only method of measuring subfloor relative humidity levels with certainty, and the method advocated by British Standards, is to use a calibrated hygrometer. Affixed to the subfloor using butyl tape to create an airtight seal around the base of the instrument, these devices measure the relative humidity of a small volume of confined air in equilibrium with the subfloor, taking into account the ambient temperature.
www.f-ball.com
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