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Beware wayward installations in winter weather

Beware wayward installations in winter weather
Martin Cummins

Published by Martin Cummins - UK Technical Service Manager, Bostik

Martin has been involved in the industry for over 20 years. He’s passionate about flooring in all its guises, with his particular expertise being in subfloor preparation products and adhesives. Martin is an active member of the CFA manufacturers committee and he sits on the CFA council. He aims to keep abreast of all the changes in the industry and feeds this knowledge back to installers to make sure when floors are laid they perform to their maximum potential.

While packing for my annual holiday to take me to warmer climes this year, I couldn’t help thinking what the weather would be like on my return. Winter seems to approach a lot more quickly than we’d like every year, and it brings extra challenges for all flooring contractors.

In an ideal world, an internal trade such as professional flooring really should not have any concerns about temperatures or humidity because sites and projects should be at ‘good’ ambient conditions.

However, based on experience throughout my career, I can confidently say this doesn’t happen. New-build projects sometimes have the same conditions as the outside weather, with no windows and heating only in localised areas where trades are working (or in the offices).

Refurbs often don’t have any heating at all and have trades moving through, which effectively gives a corridor for the outside weather to move inside. If we base our discussion on weather being cold and damp (even rainy) outside, then we can look at where the challenges and product limitations lie.

The cold weather brings a multitude of challenges to the installer. Regardless of the materials we supply as a subfloor and adhesive manufacturer, there are significant issues with floor coverings themselves.

Failure to get the building up to ‘acceptable’ temperatures will result in resilient floor coverings being a lot more rigid and difficult to work with. If the products are cold – and by cold we’re talking 15deg C and below – coving vinyl, cutting linoleum and general manoeuvrability all become problematic.

The colder the product is, the less flexible and resilient it becomes, making it far harder to install. Textiles are less problematic when temperatures aren’t so well controlled.

“The colder the product is, the less flexible and resilient it becomes, making it far harder to install.”

When it comes to damp atmospheres, the problems with timber come into their own. Following the manufacturer’s guidelines, you’ll read something along the lines of: condition and install the timber in the environment that the building will be in when in service. This is crucial as timber takes in moisture from the atmosphere quite readily and will acclimatise to ambient conditions.

Therefore, excess moisture in the timber at the time of install will cause it to shrink as it dries out over time. Although the best adhesive will keep the flooring bonded, it cannot prevent the upper surface shrinking back and causing cupping in the timber.

If floor coverings suffer a bit, what happens to the materials below them?

Cold smoothing compound products will react far more slowly and drying times will vastly extend. Note that all datasheets will advise on curing and drying times based on good ambient conditions but these are typically 20deg C+ and 60% RH, so don’t expect the same performance at low temperatures.

To give you a fighting chance, you should avoid storing bags and bottles in the back of a cold van overnight. Owing to their bulk density the powder will be difficult to warm up again, while liquids can freeze, making them unusable. It’s usually said temperatures below 5deg C can prevent a loss of moisture from products, so not only will the curing of the compound be slowed down, but they may not even dry out!

Don’t accept working in such cold conditions or you’ll find yourself facing significant problems with smoothing compounds.

Given long enough, products may still work above 5deg C but it’s a timely challenge to get the polymers to work and the product to trowel out effectively.

You need to be at a minimum of 10deg C to get a reasonable performance, so fight for good conditions every time. If time is of the essence, look at the faster curing and drying products such as SCREEDMASTER SL C 910 SPEED 30, which will give you the best drying pattern, albeit they may still be elongated to overnight or longer.

Water-based products will be affected by temperature, and more so when coupled with high humidity and dampness. Most primers are water-based so drying will be delayed but the bigger issue is with adhesives.

In bygone days when solvent-based adhesives were acceptable, the problems were much less prevalent and conditions never needed to be particularly good – now they definitely do. Adhesives are generally thicker products.

“In bygone days when solvent-based adhesives were acceptable … conditions never needed to be particularly good – now they definitely do.”

Even under good conditions, it takes time for the water to evaporate and create the required tack to bond the flooring. In the cold, their viscosity (thickness) increases and they want to hold onto their moisture, which can greatly extend the tack time.

The amount of tack can also be significantly less when a polymer/adhesive is cold, so bonding the floor covering will be more difficult, particularly when the floor coverings themselves are more rigid.

A bigger concern is when using pressure sensitive products, such as tackifiers or adhesive tapes. Low temperatures rob them of their main performance characteristic: stickiness. In addition, cold or damp conditions often result in condensation on surfaces, which will negate the adhesion we’re trying to attain.

Finally, the product ranges that rely on the reactivity of materials, such as two-pack epoxies or even PU products, will have a much slower curing time in the cold. If the temperatures drop below 8deg C, this can permanently affect the curing mechanism, particularly with thin film epoxies such as DPMs.

“If the temperatures drop below 8deg C, this can permanently affect the curing mechanism.”

They’ll never fully cure so will not give the required performance to fulfil their function. As with pressure sensitive products, surface condensation also results in poor adhesion to the substrate when bonding with epoxy products. So, again, get the temperatures up.

In summary, in cold and damp conditions:

  • Resilient flooring products are difficult to use
  • Smoothing compounds do not cure efficiently
  • Primers will not form a film
  • Adhesives cannot dry or tack off effectively and fail to hold the floor coverings
  • Pressure sensitive adhesives will not adhere
  • DPMs don’t cure effectively

I haven’t even discussed what may happen when the building begins to warm up and materials expand, bubble, tent, de-bond, warp etc.

Snagging becomes a significant expense and time drain on the contractors, with manufacturers sometimes needing to visit projects to assess exactly what’s gone wrong.

Let’s avoid these lengthy snagging lists and put the pressure on main contractors. You should only carry out your work in accordance with British Standards and manufacturers’ guidance – prevent the issues and protect your profits while enhancing your reputation.