Under floor heating ( UFH )

All of our flooring systems are suitable for installing over a UFH system, our concrete/resin floor systems are more efficient over UFH and is natural, warm to the touch.
We have put together a few basic steps when considering choosing UFH.

It would be highly recommended that a certificate is obtained from the company that installed the UFH system to ensure that ist is fully operational with controlled temperatures so that the surface temperature does not exceed 27 degrees centigrade, preferably with flow control valves and not thermostats.

Choice of System
Please refer to https://www.uhma.org.uk/ for the best type of system to use to correspond with your current floor type, height restrictions.
Mat systems are acceptable for background heat and many are now getting effective but generally hot water systems are more efficient.
Heated wire systems should be switched off for 7 days after the floor covering has been installed.

Some of the hot water systems do not control the boiler temperature properly which can lead to hot spots and other issues affecting whatever you lay on the floor.
Please make sure the pipe temperatures are controlled by the valves and not the thermostat, and the again the heat must not exceed 27 degrees centigrade which is the maximum for soft floor coverings as well..i.e LVT

Floor types
Concrete sand and cement or Anhydrite/Gypsum
Currently anhydrite floors must be treated differently to traditional sand and cement floors, as flooring installers are realising to their detriment.
Please follow this link for further information and technical paper on these calcium based screeds :

Anydrite screeds are a mixture of screeding sand and gypsum binder, these will require more time for the drying process, moisture drying from the base upwards.
A typical dpm can not be applied as the moisture will break down the dpm coating via a chemical reaction called Ettringite.

Pre-installation measure
Make sure the system has been commissioned as per the individual manufacturer.
Water fed system, gradually increase the temperature of 5oC per day up to the maximum flow temperature(over 4-5 days).
Once this temperature has been reached , hold for a further 3 days, before gradually lowering the temperature at increments of 5degrees per day.
The above is a guide only, the manufacturers guidance must be sought prior.

Problems with decorative or Resin floor finishes with UFH
Please note the most common issues:
1. Dramatic changes in the surface temperature
2.Hot spots in the floor
3.Lack of heat distribution
4.Hugh humidity in the room
5.Temperature of the floor rising above 27degrees

Tell tale signs of the effects of the above
1. Cracks or hairline fractures
2.De lamination
3.Lack of effective heat transfer through the floor finish.

Please note: No floor finish must be installed without the UFH commissioned.
After commissioning, the installer should provide documentary evidence of commissioning, particularly the temperatures achieved at the finished sub floor, and these should be available to the trades that follow. This documentation should fully explain how the surface temperature of the screed is controlled by the flow valves.
Never exceed 27 degrees centigrade.

Always try to avoid taking the floor from one extreme of heat and humidity to another within a very short timescale.
If you do turn off the system and the floor gets cold as it can in the summer then you must turn the system back on in a controlled fashion as you would when commissioning the system. If you turn it back on to full heat this will “shock” the flooring.

Resilient flooring BS8203:
Underfloor heating will cause problems if the temperature at the interface between the subfloor and flooring exceeds 27oC, or is subject to rapid fluctuations in temperature.
There has been been discussions between various UFH manufacturers at where the temperature should be measured,
The CFA has issued a joint guidance which states that resilient flooring should not exceed 27oC at the underside of the floor covering(adhesive line), some may refer to this as the interface temperature.