ON THE BALL: SOLUTIONS FOR DEALING WITH DAMP
Stephen Boulton, Technical Service Manager for F. Ball and Co. Ltd., gives his advice on how to avoid floor failure as a result of subfloor moisture.
Subfloor moisture, including residual construction moisture, is the leading cause of floor failure. If subfloor moisture levels are too high and contractors don’t take the necessary precautions when undertaking flooring installations, moisture can rise up and adversely affect adhesives, floorcoverings and levelling compounds (if they are not moisture tolerant), possibly causing complete floor failure. Fortunately, multiple solutions are available.
up to the level of floorcoverings. There are many different damp-proof membranes on the market. The levels of subfloor moisture and any time constraints will determine the best choice for the job.
FAST-TRACK SOLUTIONS Single coat epoxy resin waterproof surface membranes are available that will fully cure in as little as three hours and will isolate residual construction moisture or rising damp where relative humidity values are up to 98%.
An even quicker option is available for the purpose of suppressing residual construction moisture. A water-based, two-coat system from F. Ball is available that only needs 15-20 minutes curing time for the first coat and a further 30 minutes curing time for the second coat to create a barrier against RH values of up to 95%.
One thing to remember before applying these liquid waterproof surface membranes, is to make sure that the subfloor is suitably prepared and free of contaminants. This includes removing any old adhesive residues.
FIRST THINGS FIRST In order to ascertain if subfloor moisture will pose a risk to a completed installation, a contractor can determine the levels of subfloor moisture by carrying out a moisture test. In the first instance, this can be done using a handheld device. If this indicates a high level of subfloor moisture, F. Ball recommends the use of a digital hygrometer, in accordance with British Standards, for a more accurate reading. When affixed to the subfloor and left for a period of time, determined by the thickness of the subfloor, a digital hygrometer will provide a measurement of subfloor moisture expressed as a relative humidity (RH) value.
Where a moisture test indicates that the relative humidity (RH) level within the subfloor is above 75% (65% if wood floorcoverings are to be installed), some form of moisture management system will be necessary to minimise the risk of floor failure.
The most common method of moisture control is the application of a liquid waterproof surface membrane. These are applied to the subfloor using a trowel or roller and, when cured, serve as a physical barrier to stop moisture rising
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ANOTHER OPTION An alternative solution to applying a liquid waterproof surface membrane, is to use an isolator membrane, such as F. Ball’s Stopgap Isolator Membrane. Like traditional damp-proof membranes, these impervious, loose-lay sheets act as a physical barrier to impede the passage of moisture from a damp subfloor to floorcoverings. Nodules on the underside of the membrane create an airspace that allows for the ventilation of water vapour from a damp subfloor to the edges of a room, protecting the floorcovering from the damaging effects of excess subfloor moisture
Unlike liquid waterproof surface membranes, isolator membranes can also be used where floorcoverings are being installed over a subfloor that needs to be preserved in its original condition, such as heritage projects, or when installing temporary floorcoverings. They are also ideal where a subfloor is contaminated, with paint, oil, or old adhesive residues.
Together, these systems for dealing with damp provide for practically any eventuality. Contractors should take the time to assess what the most appropriate system is for a particular job.
www.f-ball.com www.tomorrowscontractfloors.com
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