Apply A Surface DPM Or Cross Your Fingers And Hope For The Best?

Dampness is one of the biggest cause of failure in contemporary flooring installations.  We’ve all been to sites where the existing vinyl flooring is blistering and lifting. Or the joints are splitting, not due to poor welding, but because the adhesive has been degraded by moisture and has released the flooring, putting stress on the welded joint that it was never designed to cope with.

It is a common story repeated thousands of times a year and is due to a number of factors. Fast-track building practice, where insufficient time is available to allow sub-floors to dry out adequately, is a constant concern to all manufacturers of contemporary floor coverings; when a failure occurs it is often the floor covering which is blamed - at least until the true cause can be proved. In such a time-pressured situation, some flooring contractors may be “bullied” into installing flooring using acrylic or pressure sensitive adhesives, which as a general rule have the moisture resistant properties of flour and water, onto sub-floors which cannot be fully dry.

Old buildings without an integral DPM are also a common source of damp related problems, particularly when old flooring, such as tiles fixed in ATA (Asphalt Tile Adhesive), is lifted and a new sheet vinyl is laid. Any moisture present in the sub-floor or passing up from the earth no longer meets a barrier of a moisture repellent adhesive or the tiling itself. Rather than continuously permeating the old tiled floor covering via the joints, it now builds up to a point where it can cause problems. With the new floor covering any such moisture will first hit a layer of adhesive which is at best moisture sensitive and not designed to deal with moisture levels in excess of 75% RH. Furthermore, the plasticised sheet flooring which has replaced the semi rigid tiling is flexible and unstable when loose, resulting in rapid failure once the ‘flour and water’ have given up the ghost.

It doesn’t have to be this way and often isn’t.  Anyone with a bit of common sense would test for moisture as a matter of course before proceeding with any flooring work onto a cementicious surface, even above ground level on new build if it is found that the RH level is 75% or above. Any sensible person would take steps to avoid the situation where everybody looks to you as the expert for a solution once the job has gone wrong, often at your expense.

Should you find that the sub-floor is too damp to proceed with a flooring installation, the obvious and cheapest answer is to let it dry either naturally or speed up the process with de-humidifiers. If this is not an option due to time constraints, the application of a surface DPM is the logical conclusion.  Altro has developed three surface DPM systems to cope with varying levels of dampness in sub-floors, ranging from 90% to 97% RH.

Alternatively, you could look to our revolutionary new XpressLay range. Altro XpressLay is the first ever safety floor which can be installed using tape rather than traditional contact adhesive, making it extremely quick, easy and clean to fit. It can be laid over existing problem surfaces such as vinyl tiles or flaky painted floors, and its unique product formulation and profiled underside means that it can be used on fresh concrete sub floors up to 97% relative humidity, meaning there is no need to wait for a new concrete sub floor to reach 75% RH or apply a surface damp-proof membrane.

So, to conclude, moisture really is the biggest single cause of failure in contemporary flooring installations - don’t let one of your jobs add to the total.

This article first appeared in the January 2010 edition of the CFJ.