Structural engineered flooring is among the most stable wooden floor products available and is therefore
ideal for use with under-floor heating (UFH).
However, to obtain the best performance of your floor in the long term it is important to follow these
guidelines. As there is no reliable way of recording or monitoring the heating-system settings and room conditions over time, it would be impossible to prove or disprove whether all the guidelines had been
followed: therefore, we cannot give a guarantee. We are however working in conjunction with a couple of
underfloor heating manufacturers who are testing the product vigorously with a view to putting a guarantee
in place in the future.
Make sure the UFH system is installed, fully working and tested before installing your floor; you risk
causing irreversible damage if you cannot fully control the system and do not restrict the operating
temperature according to the guidelines below.
In practise the flooring is almost certain to shrink when used with UFH, and there will be some movement of
the floor. This is due to the relatively high moisture content; the solid-wood wearlayer is about 10% and the
ply core about 14% when the planks come out of the factory, and these levels cannot be reduced in
advance through re-kilning, for example, without affecting the integrity of the plywood.
After a months use with UFH, these levels can drop to 6-7%; this loss of moisture manifests itself as
shrinkage. If the moisture loss is severe, there can be a breakdown in the cellular structure of the wood,
leading to splits in the wear-layer.
For maximum satisfaction, these effects need to be minimized and we recommend
The manufacturers preferred method of UFH is water/piped systems rather than electric mats or film.
Manufacturers recommend using the 189mm board rather than the 220mm for UFH and where possible,
each plank should be fixed in place, either stuck or secret-nailed/screwed. If planks are loose-laid there will
be an accumulation of shrinkage in one place, which may mean a gap of 1cm or more somewhere in the
floor. Instead, the effect of shrinkage will be limited to about 0.5mm on each plank.
If floated as a raft – boards stuck together, but not fixed down – the whole floor may move in an
unpredictable way, especially if the room is irregularly shaped.
Some species are more suitable for use with UFH than others – merbau, walnut and oak are particularly
stable. On the other hand, the more “lively” species – hard, brittle woods, such as maple, jatoba and larch –
tend to react by splitting and moving more readily. We recommend these species are not used with UHF.
Wood should be sealed as soon as possible after laying. Oiled floors should be fed and maintained more
often than conventional, non-UHF oiled floors.
The use of standard, micro-bevelled planks will minimise the visual impact of shrinkage. A square-edged
board will show up the shrinkage much more through slight gapping.
Installation on a screed based system.
The screed must dry naturally to below 4% moisture content – the UFH should not be turned on before the
correct moisture level is achieved. The screed must be level to +/-3mm over 3m.
An MS Polymer adhesive such as Proflex, should be used, this will act as both adhesive and moisture
barrier. For increased peace of mind a coat of Proflex Fastrack DPM could be applied to the screed before
After fitting the flooring adhesive should be allowed to cure for 2 days before the heating system is turned
For all types –
The maximum temperature at the underside of the wood should be 26C and Relative atmospheric humidity
should be maintained between 40-60% – using climate control or a de-humidifier.
The heating system should initially be turned on at the ambient temperature. It should then be raised at no
more than 1C per day until the desired temperature is reached.
The room temperature should be maintained between 20-23C
The heating system should be run in strict accordance with the manufacturers’ instructions.
Beware of leaving slid furniture and/or heavy rugs in one position for any length of time. If the floor is
“capped” in this way, the wood may be affected by excessive heat, which cannot escape normally. This will
lead to cupping or gapping, from which the floor may not be able to recover.