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Not your typical winter working warning

Choose the right products, condition and acclimatise the materials in the intended environment, and very little should go wrong with respect to the temperature, says Steve Thornton.

THERE’s an annual tradition to warn of the coming of winter, the cold conditions and the chaos that ensues within the flooring industry. We’ve all witnessed the impact that this has on building sites and the environments where our products are applied and installed.

But difficult site conditions aren’t unique to winter – what about summer? This can also be a tricky environment to navigate, and what about everyday situations where the conditions fluctuate?
The reasons that the cold spell can cause such an impact on product performance are actually present throughout the year.

The effects may be the polar opposite in the summer, but they exist in almost every installation to a lesser or greater extent.

Ambient temperature
Temperature plays a critical role for any installation. The key element for temperature during the installation is not necessarily what the temperature is, it’s whether the temperature is stable. Standards dictate that temperatures need to be ‘steady’, which is between 18deg C and 27deg C before, during and after installation, and the critical word in that statement is ‘steady’.

Achieving these temperatures and maintaining them is difficult in winter but also troublesome in summer. Often, heating or temperature control will not be provided during summer months and applications and installations will go ahead in very hot conditions.

This is the opposite in winter, where the heating may be non-existent, but the installations still go ahead in very cold conditions.

Extreme conditions
Summer 2023 saw temperatures reach more than 30deg C, albeit briefly. What issues does this cause? Well, quite a few, surprisingly. First, it’s likely any material to be used is already very warm owing to being stored in the back of transportation vehicles that have very little protection from the heat, or maybe stored on pallets outside the job site.

In the case of smoothing compounds, resins and adhesives, this can speed up their reactivity and/or reduce the working time significantly. So, when you mix a smoothing compound and it has been stored in the back of a van or on a pallet in the baking heat, the reactivity is increased and it’s already wanting to set quicker. Then you pour it out into a very warm environment with very low humidity and this speeds things up further. During winter, the cold weather can have the opposite effect on product performance.

Floorcoverings and accessories can also get very warm when stored in these conditions. This means they can only really get cooler – drastically increasing the chance of shrinkage. In the winter, you guessed it, materials are very cold and can only get warmer – leading to expansion.

Subfloor temperature
The minimum advised subfloor temperature is 10deg C, and this is where things get a little more precarious. We can install flooring with an air temperature of up to 27deg C, but we only need 10deg C for the floor temperature? This is where we come back to the word ‘steady’.

If the air temperature is steady, then the floor temperature will gradually rise and start to mirror that of the air. The air is easy to heat, but the thick concrete slab is much more difficult, so whatever it gains in temperature throughout the day, it loses again overnight – much more quickly than it gained it.

It’s a good way to tell whether the site conditions are controlled, as the temperature of the slab should be within a few degrees of the air. If it isn’t, you need to make allowances.

The effects on product performance
Now that we’ve looked at some of the environmental issues that can occur onsite, let’s have a more in-depth look at the knock-on effect these can have on product performance.

You’ve put the smoothing compound down and it dries too quickly, then you come back the next day and sand it to try to get rid of the trowel marks and spike roller marks that remain. Then you feather all the floor to repair the bits you couldn’t sand out, then you sand it again and vacuum the floor and you’re ready to go.

That’s a lot of unnecessary work, all because the site conditions weren’t controlled and stable. In winter, the smoothing compound may not be dry the next day, which can be equally frustrating for all interested parties.

You spread your glue to the entire room, and you get your nice warm LVT tiles out and start to fit them. Because the weather is warm, it’s likely the humidity is low – this means the air is starved of moisture. The air is thirsty, so all the moisture that is in the adhesive, which wants to evaporate, is being sucked up by the air much more quickly than usual. This reduces the waiting time, ‘great’ you may think – I can get fitting it sooner. But this also vastly reduces the open time – meaning you have a much smaller window in which to work – not so good. Dry air will keep sucking all the moisture out relentlessly and now the chance of late placement into the adhesive is greatly increased. When it’s cold, airing time is increased and the chance of going in too early and trapping excess moisture in the adhesive is likely.

Then your nice, warm LVT tiles are laid onto a much cooler floor and they do not like it. We all know that flooring has a high likelihood of expanding if it gets warm, and contracting if it gets cold. Day turns to night, and the nice warm air starts to cool down. The tiles that were happy and cosy at 30deg C were placed onto a colder floor, and then the entire room gets colder, and this is before the adhesive has gathered its full strength.

So, the flooring contracts and gaps form at joints and perimeters. In winter when the floors are cold, and the heating is turned on later in the project, the floors expand and things start to lift at the joints – either way, it’s not ideal.

There are many aspects to consider for installation environments, some are mentioned above, others may include ventilation, dew point and condensation, thermal shock, thermal cycling, or solar gain.

The fact is that it doesn’t really matter whether it is winter, summer or anywhere in between. The installation environment is critical at all times of the year.

The conditions should match the final intended conditions of the building as best as possible. And the key word is ‘steady’ – keep the conditions controlled and stable. Choose the right products, condition and acclimatise the materials in the intended environment, and very little should go wrong.
Steve Thornton is technical manager – wall and floor at Bostik

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