Be alert for a dewpoint situation

‘‘The dewpoint is really neglected,’ says technical sales adviser Erik Schutte. ‘We always pay attention to ambient temperature and ventilation, but in fact, a dewpoint situation can really ruin your project. Therefore, always stay alert.

The dewpoint is the temperature at which water vapour in the air is at its maximum. There is then 100% relative air humidity. Everyone knows that when the temperature drops, water vapour will condense. This condensation can settle on colder surfaces such as floors and walls. This physical process takes place all year round, in summer and winter, and can lead to moisture problems – before, during and after finishing the floor or wall.

With the large temperature differences we’ve been experiencing recently, it’s certainly important to stay alert. If you come into work and there’s condensation on the inside of the windows, the alarm bells should start ringing. Don’t start working before first measuring the dewpoint temperature. There are handy tables and meters for that. We also provide information on the specification sheets. As a rule of thumb, the floor temperature should be at least 3 °C higher than the dewpoint temperature.

As I already mentioned above, the dewpoint often isn’t taken into account, but I note that we’ve been getting more and more questions about it – for example, because a project failed. I last saw it happen on a project using LiquidDesign. We recommend a maximum humidity of 70% when processing LiquidDesign. If you start painting in a dewpoint situation, the paint will disbond and you’ll get blisters. A floor like that comes loose and you have to start all over again. The climate conditions absolutely need to be okay.

What applies to floors and walls also applies to the materials to be processed. Therefore, never start working immediately with a floor covering brought in from a colder or warmer storage area, bus or van. You should preferably let it acclimatise in the project environment for at least 24 hours in advance. The same applies to primers, levelling compounds and adhesives.

In some tiling projects, you can also need to deal with dewpoint situations, as a result of which, for example, the substrate remains moist for too long and adhesive or grouts don’t set properly. Therefore, by adhering to the processing instructions and safety margins stated on the specification sheets, you’ll always be doing things right. Do you still have doubts about the working conditions on site? Our Customer Service department and technical sales advisers are happy to give advice on your project whenever necessary.’