Neil Sanders of F. Ball and Co talks through the steps to ensuring a flawless finish when installing floorcoverings using Luxury Vinyl Tiles.
The increasing quality and variety of Luxury Vinyl Tiles (LVTs) and their suitability for a wide range of settings has seen their appeal continue to grow.
Given high expectations for such installations, ensuring a long-lasting, visually attractive flooring finish is essential when installing them. In line with BS 8203:2017 ‘Installation of resilient floor coverings,’ this should involve following basic principles of subfloor preparation, as well as taking precautions to avoid common causes of floor failure, and selecting the optimum installation products at each stage of the process.
The first step in any flooring installation should be to check that the subfloor is suitably sound, smooth and dry. To avoid costly floor failure, any ‘laitance’ (particles on the surface) and contaminants should be mechanically removed before proceeding with a flooring installation.
GUARDING AGAINST DAMP
At this stage, a moisture test should be conducted to determine if the subfloor is dry enough to receive floorcoverings. Excess subfloor moisture, whether residual construction moisture or rising damp, is the leading cause of floor failure, resulting in costly recalls and delays.
The only method of measuring subfloor relative humidity levels with certainty, and the method advocated by British Standards is to use a calibrated hygrometer. Where subfloor Relative Humidity (RH) levels are higher than 75%, a moisture management solution will be required to prevent moisture attacking flooring adhesives and causing resilient floor coverings to blister and lift.
Liquid waterproof surface membranes are available that will isolate excess subfloor moisture where relative humidity values are up to 98%, with a single coat application, and fully cure in as little as three hours.
In most cases, the next step in the subfloor preparation process should be to prime the subfloor. When used over non-absorbent surfaces, such as waterproof surface membranes, primers promote adhesion between the subfloor and the levelling compound applied over it. Applied over absorbent subfloors, they also stop the unacceptably rapid drying of levelling compounds.
Priming also prevents ‘pinholing.’ These are small holes in the levelling compound that have the appearance of pinholes or blisters caused by the slow escape of air from absorbent surfaces as the levelling compound cures.
General-purpose primers are available that can be used over both absorbent and non-absorbent surfaces. There are also specialist primers for use over non-absorbent surfaces, and others for calcium sulphate screeds.
CREATING A BASE
A levelling compound should then be applied over the subfloor to create a perfectly smooth and level surface onto which LVTs can be installed. This ensures that the visual appearance of the floorcovering is flawless and not compromised by imperfections in the subfloor showing through.
In heavy-duty areas, where installations will be subject to heavy loads or high foot traffic, the use of a heavy-duty levelling compound is recommended. The high compressive strength and excellent self-levelling properties of these levelling compounds will create the perfect base for the installation of LVTs.
When working over subfloors of plywood or steel, the application of a flexible levelling compound is advised to accommodate movements in the subfloor and prevent cracking in the levelling compound affecting the finished appearance of an installation.
Where an LVT installation is part of a refurbishment and old adhesive residues are present after the removal of old floorcoverings, specialist levelling compounds are available that can be applied straight over old adhesive residues, without the need to prime beforehand, removing the need for mechanical preparation. Normally, adhesive residues need to be fully removed before applying a levelling compound.
Pressure sensitive adhesives are often the best choice for installing vinyl tiles or planks. They form an instant grab upon contact, so contractors don’t need to worry about tiles or planks moving about when they are working, making them ideal for where intricate designs or patterns are being created.
Pressure sensitive adhesives are available with a variety of other specialist attributes, including the ability to hold vinyl floorcoverings firmly in place in areas exposed to extreme temperature fluctuations (from -20°C to +60°C), such as conservatories and other heavily glazed areas subject to solar gain.
It is important to remember that some adhesives require rolling with a paint roller that has been coated with the adhesive to flatten the ridges formed by application with certain kinds of trowel. This is to reduce the incidence of these trowel ‘serrations’ shadowing through thin vinyl floor coverings and affecting the appearance of the finished installation. However, some adhesives do not require rolling, so it is best to check the
The temperature of the floor must also be maintained above 10°C throughout the application and drying of the adhesive, and underfloor heating should be turned off for at least 48 hours before, during and after application to enable full bond strength to be achieved.
Finally, it is highly recommended that contractors always check the compatibility of particular floorcoverings and adhesive. To do this, you can consult the floorcovering manufacturer’s guidelines.
Neil Sanders is technical director at F. Ball and Co