Focus on floors: your questions answered

We've picked some of the most frequently-asked questions from the hundreds answered by F. Ball’s technical team in the past few weeks.

Q. A customer wants vinyl tiles installing over cracked ceramic tiles. What’s the best course of action?

A. As long as the tiles are sound and well bonded to the subfloor, you don’t need to remove them. You can apply a levelling compound before installing new floorcoverings. Make sure to prime beforehand – Stopgap P141 is F. Ball’s primer designed especially for use over non-absorbent surfaces, such as ceramic tiles. You should select a levelling compound that offers high strength and excellent self-levelling properties, such as Stopgap 300 HD. Also, choose a vinyl adhesive with pressure sensitive characteristics, like Styccobond F46. The instant grab afforded by such adhesives will help with placement of vinyl tiles.

Q. I’m looking for a low VOC adhesive to secure carpet tiles that have come loose in office areas.

A. Styccobond F41 carpet tile tackifier dries to create a permanently tacky film to prevent ‘loose-lay’ carpet tiles from moving under normal traffic, whilst allowing individual tiles to removed if they become worn or damaged. It can be used to replace individual tiles and is also solvent-free and certified EMICODE EC1 Plus, making it suitable for use in areas that need to remain in-use while the installation takes place. Styccobond F41 has recently been reformulated to be easier to apply and faster to dry, as well as offering improved coverage and tack.

Q. How can I be sure that the adhesive I choose is compatible with a particular floorcovering?

A. You can check the manufacturers guidelines. Alternatively, you can consult F. Ball’s Recommended Adhesives Guide (RAG). It’s the industry’s most authoritative guide to floorcovering and adhesive compatibility and features 6,000 up-to-date adhesive recommendations for floorcoverings, endorsed by around 200 leading international manufacturers. You can get it on the F. Ball website, as an app, which can be downloaded for free and as a printed booklet.

Q. How should I prepare a newly-installed concrete screed ahead of installing vinyl floorcoverings?

A. First, make sure the screed is suitably sound, smooth and dry. Newly-installed screeds will have a layer of laitance – a crust of cement and fine aggregates formed on the surface of the screed as it dries – which will need removing by mechanical means. If it’s not been long since the screed was installed, it’s likely that it will contain a high level of residual construction moisture. Conduct a moisture test using a digital hygrometer to determine levels of subfloor moisture. If a moisture test indicates subfloor relative humidity (RH) levels are above 75% (65% if wood floorcoverings will be installed), you’ll need to install a waterproof surface membrane, such as Stopgap F77 or Stopgap F78, before proceeding to the next stages of the installation. You should then prime the subfloor before applying a suitable levelling compound.

Q. I’m preparing to install floorcoverings over a calcium sulphate screed and a digital hygrometer is giving a reading of 92% RH.

A. The screed is far too damp to proceed with the installation of floorcoverings. Doing so would risk floor failure as the moisture will rise up to the level of the floorcoverings, attack adhesives and potentially causing complete floor failure. The only solution is to let the screed dry out properly, until the reading is below 75% (65% if wood floorcoverings will be installed). This can be speeded up by ensuring areas are well-ventilated, by opening windows and doors or using a dehumidifier, as well as by turning on any underfloor heating system to encourage the evaporation of moisture. Bear in mind that calcium sulphates screeds dry from the bottom up, unlike concrete, so a moisture test may deliver a positive reading right up until the subfloor is completely dry. You might not have to wait very long.

Q. Can Stopgap 300 HD be filled?

A. Stopgap 300 HD is suitable for preparing both absorbent and non-absorbent subfloors in areas that will be subject to light to heavy use and can be applied in thicknesses up to 20mm. If you are looking for a levelling compound to raise the level of a subfloor above 20mm where the area will be subject to heavy loads or high foot traffic, you can use Stopgap 600 Base before capping with Stopgap 300 HD. If the reason for filling is to repair cracks in the subfloor, you should use a repair compound, such as Stopgap 400 Repair before applying Stopgap 300 HD.

Our technical team are on standby to answer questions about your projects and F. Ball products from 7.30am – 5.00pm, Monday to Friday.

Site conditions vary. Don’t rely on these specific responses for your own project. If you are unsure about any technical issue relating to specific flooring installations, contact the F. Ball Technical Service team on 01538 361633 or consult the product data sheets available from F. Ball’s website.