Vinyl flooring is a popular choice of floor covering for hospitals, schools and universities amongst others. Given that these environments require a flooring system that is durable and will last for an extended period, the old adage of getting it right the first time is especially pertinent. That is why careful attention must be paid to the correct preparation of the substrate for projects where vinyl floor coverings have been specified, to ensure a successful and long-lasting installation.
Two factors in particular are vital, and equally important:
- The substrate must be fully cured and have attained the moisture content stipulated by the manufacturer of the vinyl floor covering. Excessive moisture in the substrate, or high moisture vapour emission rates, will most certainly result in an installation failure, i.e. the vinyl flooring ‘bubbling’ or delaminating from the substrate.
- The substrate must be integrally sound, smooth and level. Vinyl floor coverings will suffer from surface imperfections or a poor aesthetic appearance if the floor below is not perfectly smooth and flat.
Moisture levels in the substrate
Before installing a polymer-modified underlayment or vinyl overlayment, moisture testing of the substrate should be done. If there is no damp-proof membrane below a surface bed, or if moisture levels do not attain 5% (75% RH) or less, a suitable moisture, or vapour barrier such as TAL VaporStop HB should be installed. This will prevent the passage of water vapour and moisture through the concrete slab into the underlayment compound and vinyl sheeting layers. The WFT (Wet Film Thickness) application rate of the vapour barrier can only be accurately determined by the results of the M.V.E.R. (Moisture Vapour Emission Rate) testing.
It can also happen that the moisture content of a concrete substrate can fluctuate according to the season, so it is highly recommended that a vapour barrier be installed even if the floor appears to be dry at the time of the vinyl installation.
The TAL VaporStop HB application should be extended (dressed) onto all adjacent walls where a vinyl skirting/coving is to be installed, up to the intended height of the vinyl skirtings/covings.
As resin-based vapour barriers are not generally compatible with cementitious underlayments, the wet vapour barrier should be fully binded with a suitable, well-graded silica aggregate to prevent delamination of the underlayment. Once dried, all loose aggregate particles should be removed by sweeping or vacuuming.
Selecting an underlayment
Consideration of the service area is key in selecting a screed or underlayment, for example, in hygiene areas, a casein-free compound is recommended such as TAL Screedmaster. The underlayment must also be suitable for the traffic conditions, i.e. foot traffic, roller castor wheels, etc. Rapid-setting shrinkage-compensated underlayments will ensure a fast turn-around for the project.
Once the underlayment has cured, floor level surveys and moisture testing must again be carried out to verify the substrate is suitable to receive the selected floor covering. The vinyl flooring can then be installed onto the prepared floor, using an appropriate adhesive in accordance with the manufacturer’s instructions.
For further information on preparation of substrates and specifications for vinyl flooring systems, contact the TAL Technical Advisory Centre on 0860 000 TAL (825).