Ensuring proper site conditions is the way forward, says Rob, as prevention is better than cure.
There are many factors that affect the installation of floorcoverings in new build projects. Sites often lack windows and heating with multiple trades moving through, which effectively creates corridors for outside weather conditions to penetrate the building. This means indoor conditions can match the cold, damp weather outside. On the flip side, high temperature and solar gain can also have a knock-on effect on installations. Both scenarios share a potential decremental effect on the overall application of the subfloor preparation and adhesive products, and the floor coverings themselves.
This is why a collaboration between all stakeholders is crucial to maintain appropriate conditions before, during and after installation.
While the construction industry should ideally prevent these issues, the reality is different. When visiting construction sites, it’s not uncommon to find buildings that aren’t fully weather- and watertight, and within acceptable temperature ranges.
Cold weather and humidity
The CFA’s winter warming campaign sets the scene well – without correct heat levels on site, installation failure is likely. While air temperature is crucial, it’s equally important to assess the subfloor temperature as it often differs from the ambient temperature. In most cases, the subfloor surface temperature should be no less than 10deg C.
For a cement-based substrate to dry properly, the relative humidity in the air above needs to be lower than that of the substrate. Otherwise, it’s not going to dry naturally.
Since ambient temperature (the average temperature of an environment) can vary significantly, it’s essential to assess the extremes.
Materials should typically be acclimatised within a range of 18deg C to 27deg C, though specific ranges depend on the product (manufacturers can provide exact specifications). This prevents adverse effects on cure times of smoothing compounds, adhesives, and the flooring itself once adhered and cut into position.
Area temperature and humidity must be as close to the conditions in which the floor will ultimately be used, and these conditions should be attained 48 hours prior to the installation. Flooring materials should then be unpacked and allowed to acclimatise in the room before installation. It is equally important that these conditions are maintained throughout the installation of the flooring and for 24 hours afterwards, or until the adhesive has cured.
Materials
Each layer of the installation has different optimal temperature requirements for best results. Smoothing compounds and liquid DPMs are susceptible to low temperatures, leading to extended drying times that can disrupt project schedules and potentially cause product failure. While product datasheets specify curing and drying times, these are typically based on good ambient conditions of 20deg C+ and 60% Relative Humidity, so we can’t expect the same performance at lower temperatures.
Today’s diverse range of floorcovering materials each respond differently to temperature. Resilient floorcoverings require flexibility, but low temperatures cause them to stiffen, making them difficult to apply. Cold conditions can also make rolls of flooring difficult to unroll without cracking and harder to lay. Tasks like coving vinyl, cutting linoleum, and general manoeuvrability all become more challenging with cold materials.
Again, it’s essential with most floorcoverings that they are laid in the same humidity conditions as would be expected in use. We need to be cautious when using temporary heating equipment to warm buildings to achieve the required temperature, as it can also increase the humidity to a markedly higher level than would normally be expected.
Also, turning off heaters at night in cold weather will lead to condensation as the air cools, causing water pooling on the surface of the floor, so heating needs to be maintained.
Fitting floorcoverings in new buildings before heating and humidification systems are operational can lead to significant dimensional stability problems and must be avoided. This includes proper commissioning of underfloor heating systems that I have previously covered in another article.
To reduce the likelihood of failure, avoid storing materials in the back of a cold van overnight as liquids can freeze, making them unusable.
Temperatures below 5deg C inhibit loss of moisture from products – not only slowing compound curing but potentially preventing drying altogether.
Water-based products are also significantly affected by temperature, especially in high humidity and damp conditions. While drying delays affect most water-based primers, adhesives face greater issues.
Even under good conditions, water-based adhesives need time to evaporate moisture and develop the required tack to bond the flooring. Cold temperatures increase viscosity (thickness), causing the adhesive to retain moisture for longer, significantly extending tack time on certain products.
There are also concerns when using pressure-sensitive products, such as tackifiers or adhesive tapes. Low temperatures take away their main performance characteristic – stickiness! Cold or damp conditions can also result in surface condensation.
In summary, cold and damp conditions make products more difficult to use.
Dampproof membranes don’t cure as effectively, primers don’t form films, smoothing compounds do not cure efficiently, adhesives don’t dry or tack off properly, and pressure sensitive adhesives do not adhere to floorcoverings.
British Standards, manufacturers’ guidance, and best practice help prevent these issues while protecting profits and reputation. BS 5325, BS 8203, BS 8204 and BS 8425 advise that for the installation of most floor coverings, the room temperature and humidity should create a steady work area temperature between 18deg C to 27deg C. It’s also important for this to be maintained.
As a collective, let’s ensure proper site conditions, as prevention is better than cure!
Rob Russell is technical consultant at Bostik UK
