Underfloor Heating

Under floor heating systems create quite severe localised atmospheric conditions which can affect any floor laid on to them. However, as above, with a proper understanding and by following the correct procedures, the effects can be minimised.

Under floor heating systems will create an environment where the atmosphere gets particularly dry and below the 10% moisture content of normal floors.

There are two ways of addressing this problem.

1. Fit timber with a standard moisture content.

· Unpack the flooring and stack it in the room it is to be used in with the heating on and leave to acclimatise for about four weeks. Ensure that each board has a free circulation of air.

· Switch the heating off and lay in the normal way.

· Switch the heating back on and leave on for a week

· Switch heating off and allow to cool

· Fill any resultant gaps with resin or wax filler.

· Finish the floor with an appropriate floor sealer.

· Switch heating back on

With this method the floor may shrink slightly when the heating is on and fine gaps may appear. However, these are not a problem for most people.

2. Fit flooring that has been dried to an average moisture content of about 6%

· Unpack the flooring and acclimatise as above.

· Switch the heating off and lay in the normal way.

· Switch on the heating for around a week.

· Switch heating off and allow to cool

· Fill any resultant gaps with resin or wax filler.

· Finish the floor with appropriate floor seal.

· Switch heating back on.

With this method the chance of further shrinkage is greatly reduced if not eliminated. However it is very important that if the floor is laid in this way then the heating system is kept on low ALL THE TIME or most of the time and that on no account should it be switched off for long periods when the relative humidity in the atmosphere is high. If this happens then the floor may expand to the point where structural damage could occur.

ALL THE ABOVE IS GIVEN FOR GUIDANCE ONLY AND BRITISH HARDWOODS IS NOT LIABLE FOR ANY PROBLEMS CAUSED BY INCORRECT FITTING OF A FLOOR OR FITTING IN ADVERSE CONDITIONS

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Hardwood floors and underfloor heating.                                              

Underfloor heating systems can create lower moisture contents. In this case it is obviously not possible to alter the conditions in the room and so the focus should be on allowing for these conditions in your preparations. This can be done in the following ways;

i) Specification of your floor

Choose a fairly narrow board, narrow boards will show far less movement than wide boards. The boards should be 20mm thick and should incorporate a microbevel as this will serve to shadow any slight gapping.

Note that, due to the way timber is converted from the log, European oak will tend to be far more stable than American oak and, as such, is far more suitable for underfloor heating systems.

ii) Acclimatisation

Although, as mentioned above, all floors supplied by British Hardwoods are kiln dried to about 10% and their moisture content and storage conditions carefully monitored and controlled, we suggest a further period of acclimatisation prior to installation. This is done as follows;

Unpack all the flooring and ‘block stack’ within the room so that air has as much chance as possible to circulate around every board. Slowly turn the heating on to full operating temperature over a couple of days. Leave the boards to acclimatise with the heating on for about four weeks. You may want to move the boards around during this time so each has an equal opportunity to acclimatise. After four weeks turn the heating off and allow it to cool prior to installation.

Once installed slowly turn the heating back on for one week before undertaking any filling of gaps and finishing. Filling and finishing should be done with the heat off.

iii) Operation of the underfloor heating system.

* Do not exceed 28°C unless using the Stasis™ option *

Once the floor has been installed it is advisable to keep the underfloor heating system running, if just on very low, all year round. Relative humidity fluctuates greatly over the year. Cold air in winter will contain very little moisture, yet warm summer air can be very humid. If the heating is turned off completely throughout the summer then the floor, which will have dried out through the winter, is likely to absorb moisture and expand.