Flooring installations in schools, colleges and universities often face severe time constraints, frequently requiring completion over a weekend or during a school holiday. Flooring in these locations must also deliver long-term durability, requiring contractors to select suitable products and avoid common causes of floor failure. Stephen Boulton, Technical Service Manager at leading manufacturer of subfloor preparation products and adhesives, F. Ball & Co., talks through achieving a long-lasting professional flooring finish in these settings while working to tight deadlines.
F Ball & Co. Ltd.
Installing floorcoverings in any environment requires proper subfloor preparation to ensure a long-lasting professional appearance. Incorrect or insufficient preparation can create the potential for floor failure, leading to costly recalls and remedial work. In educational settings, there can be additional pressure for projects to be completed as quickly as possible. Fortunately, the latest fast-track subfloor preparation products and flooring adhesives enable flooring contractors to do in a day what would have once taken a week.
Before undertaking any flooring installation, a thorough assessment of the subfloor should be completed to ensure it is sound, smooth and free of contaminants. If the subfloor is a newly-installed screed, laitance may still be present, and floors that are being refurbished may be contaminated with old adhesive residues. To avoid costly floor failure, both laitance and contaminants should be mechanically removed before proceeding with a flooring installation. Dust or debris should also be swept away, and damaged subfloors should be repaired with an appropriate floor repair compound.
Safeguarding against moisture
Unmanaged moisture, whether residual construction moisture or rising damp, is one of the leading causes of floor failure, causing adhesives to de-bond, carpet underlays to rot, wooden floors to warp and resilient floorcoverings to blister. Moisture can also lead to the growth of mould and bacteria, which can potentially cause a health risk. A moisture measurement test should; therefore, be conducted as part of any flooring installation to ascertain if excess moisture is present, and appropriate action can be taken if necessary, such as application of a waterproof surface membrane.
To comply with British Standards, subfloor relative humidity (RH) levels within the subfloor should be measured using a pre-calibrated hygrometer. If RH levels exceed 75% – or 65% when installing timber floorcoverings – a moisture management solution will be required to stop excess subfloor moisture damaging floorcoverings and adhesives and potentially causing floor failure.
Liquid waterproof surface membranes are the usual moisture management solution. Two-coat, water-based systems are available that create a barrier against residual construction moisture where RH levels are up to 95%, and dry within two hours.
Epoxy waterproof surface membranes are also available, in single-coat, fast-drying formulations, that will provide protection against RH levels
as high as 98% in areas of residual construction moisture or rising damp.
Once the subfloor is suitably sound, smooth and dry, or a suitable moisture management solution is in place, in almost all circumstances, it is essential to prime the subfloor. When used over non-absorbent surfaces, such as waterproof surface membranes, priming promotes adhesion between the subfloor and subsequently-applied levelling compounds. Applied over absorbent subfloors, such as concrete, sand/cement screeds or plywood, priming also prevents the unacceptably rapid loss of water from the levelling compound into absorbent substrates, maintaining its working time.
Priming also prevents ‘pinholing’; 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.
Creating a base
Once the subfloor is primed, the application of a levelling compound is recommended to create a perfectly smooth and sturdy base for the receipt of new floorcoverings.
The fastest setting products on the market are ‘walk-on’ hard in 30 minutes and ready to receive new floorcoverings from 45 minutes, allowing installations to proceed faster than ever. In education facilities, it is important to select levelling compounds that are low odour and protein-free. This ensures they are suitable for the most sensitive environments.
As has been stated, in most cases, old adhesive residues must be removed before installing a levelling compound. However, there are specialist high-performance levelling compounds available that can be applied directly over bitumen and adhesive residues which offer significant time-saving benefits for contractors. One such product, F. Ball’s Stopgap 1200 Pro, takes as little as 60 minutes to set and is ready to receive floorcoverings from as little as four hours. In most applications, including when it is applied over old adhesive residues, it is not essential to prime beforehand, saving further time.
In some areas of schools, colleges and universities, such as corridors, floors will be expected to receive high levels of daily foot traffic, so using a high-strength levelling compound will help ensure long-term durability of the floorcovering.
Choosing the right adhesive
The contractor can then select a suitably fast-working adhesive to install appropriate floorcoverings. The choice of adhesive will be determined by what type of floorcoverings are being installed and where, but there are options for when time saving is a priority.
Vinyl, which is easy to clean and maintain, is popular in educational facilities and is best adhered by an adhesive with good initial tack and high final bond strength. Nowadays, acrylic and vinyl adhesives are available that build up a strong enough bond to allow for foot traffic in less than an hour after the application of floorcoverings.
Carpet tiles are another popular choice for areas such as libraries or common rooms, not least for their ability to be removed and replaced if individual tiles become worn or damaged. For this floorcovering, a carpet tile tackifier provides a permanently tacky film that prevents the tiles from moving laterally under everyday traffic, while allowing individual sections to be lifted and replaced with ease. Carpet tile tackifiers are available that, once applied, only take 30 minutes to form a permanently tacky film ready to receive floorcoverings.
It is advisable to always check the compatibility of particular floorcoverings and adhesives. To do this, contractors should consult the adhesive manufacturer’s recommended adhesives guide or see the floorcovering manufacturer’s instructions.