Surface preparation – F Ball & Co

IN order to ensure a long-lasting, smooth base for the installation of floorcoverings, a levelling compound should be applied over a subfloor. However, F Ball & Co, manufacturer of subfloor preparation products, advises that before applying a levelling compound, it’s necessary to inspect and properly prepare the subfloor. Contractors should also take time to select the most appropriate levelling compound for the job.

First, before any floorcoverings can be installed, a subfloor must be suitably smooth and free of contamination, including old adhesive residues. On large projects, mechanical removal is the usual technique for old adhesive residues.

Contractors must also take care to ensure that the substrate is dry enough to proceed with a flooring installation. A calibrated digital hygrometer will give accurate readings of subfloor moisture levels as a measure of relative humidity (RH) and will indicate if a moisture management system is necessary.  Should a moisture measurement test indicate that the relative humidity of the subfloor is 75% or above (65% for wood flooring installations), a waterproof surface membrane must be installed to prevent subfloor moisture attacking floorcoverings, potentially causing floor failure.

F Ball recommends the use of a two-part epoxy waterproof surface membrane system, such as Stopgap F77, which can be used to isolate moisture where RH values are up to 98%, or a one-part solution such as Stopgap F78, which can be used to isolate residual construction moisture where relative humidity values are up to 95%.

F Ball waterproof surface membranes impede the passage of residual construction moisture and rising damp from affecting subsequent floorcovering installations, allowing early installation of floorcoverings in fast track building programmes.

Prior to the installation of a levelling compound, a primer should normally be applied to the subfloor. A primer prevents unacceptably rapid drying of floor levelling compounds over absorbent subfloors and promotes adhesion to non-absorbent surfaces.

Having ensured the subfloor is sound and dry or installed with a waterproof surface membrane, the installation of a levelling compound will create a uniform, smooth surface over which to install the final floorcovering.

Contractors should take time to ensure they select the optimum levelling compound for the type of subfloor and situation for which it’s required; light or heavy-duty usage, the timeframe of the project and the type of subfloor will determine the ideal levelling compound for a particular project.

If contractors are looking for a time saving solution, F Ball’s Stopgap 1200 Pro smoothing underlayment can be applied directly over adhesive residues, without the need for priming or mechanical removal.

With a setting time of only 60 minutes, Stopgap 1200 can be ready to receive new floorcoverings from as little as four hours, guaranteeing a high-quality floor finish can be completed to tight deadlines, even in areas of residue-contaminated subfloors.

Neil Sanders, technical director at F Ball & Co, explains: ‘A levelling compound provides a smooth base for floorcoverings. However, to ensure the successful installation of a levelling compound and to create a durable and aesthetically pleasing finish, the subfloor must be properly prepared beforehand by following these steps.’

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