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How To Enjoy A Problem Free Cosy Winter

John Alcock on underfloor heating

UNDERFLOOR heating is a topic I’ve covered in the past. I think it’s a great idea, not least because it’s often more economical to run than traditional alternatives.

There are also benefits in terms of space and the appearance of rooms since you don’t need to fit radiators. However, several recent technical support visits have highlighted the potential pitfalls for flooring contractors when working on properties where an underfloor heating system, (or UFH to use the shorthand version) has been installed.

As the popularity of UFH increases, flooring contractors need to know how to work with it and reduce the risk of problems, as well as manage what is expected of them from above.

One such visit was to a new build project for a local authority in Yorkshire, working to strict deadlines to have the building opened for a certain date.

The UFH had been installed with the screed laid soon after that. Although no problems had so far been encountered, the flooring contractor was being pressured by the main contractor to get the floors finished as soon as possible to meet the deadlines.

However, the relative humidity of the subfloor was still pretty high, and the UFH system was not yet switched on.
The danger here is that leaving the first

‘firing’ of the UFH until after the floors have been finished, and potentially to not under take a proper commissioning process, could mean the floor drying out too quickly and experiencing problems such as cracking of the subfloor and delamination of the finish. Then those involved face the usual discussions as to who is at fault and who should pay to put things right.

So what is the best way to deal with UFH, and how should these systems be commissioned? The latest CFA Guide to Contract Flooring is a great place for sound advice on this subject.

Essentially, making sure any UFH system is properly commissioned is crucial to keeping any problems to a minimum. The commissioning process should start by switching the system on at ambient water temperature for three days. From here, the temperature should be raised by a maximum of 5degC per day until the design
temperature has been achieved.

After leaving the system running at this level for at least four days, the process should be reversed until the ambient temperature is reached again. From here, the floor can be tested for moisture and the finish fitted.
Clearly, it seems that on some projects this sort of process is difficult to follow properly.

As with the above example, it may be that the flooring contractor is instructed to fit the finish early by the main contractor, or that the UFH may not have been fully installed and set up ready to run before flooring work is scheduled to finish.

So where does that leave the flooring contractor? The main thing is to be aware of the dangers of not commissioning the UFH properly, and to ensure that the main contractor is aware of this too.
It’s important that everyone involved understands the potential problems involved, and that there is clear responsibility should the decision be taken to finish the floor without first properly commissioning the

UFH system.

John Alcock is technical specifications manager at Bostik

T: 01785 272727

This article has been reproduced from the Contract Flooring Journal website. You can find them at