UNDERFLOOR HEATING
AND CHAUNCEY'S TECTONIC™ OAK FLOORS

Our customers are often relieved to finally find a company that knows what they are talking about! We have lots of experience with supplying wooden floors to be used over underfloor heating and can now share the benefit of our experience.

EXPANSION & CONTRACTION:

The most important point to realise is that any wooden floor is subject to expansion and contraction, according to the amount of moisture in the environment. Hence your hardwood boards may contract slightly during winter months (as central heating produces a much drier atmosphere) and expand slightly during the summer when windows are open and the atmosphere within the house has more moisture. This seasonal movement is a normal characteristic of wooden floors and it never stops - regardless of the age of the wooden floor. This expansion and contraction can also be magnified when dealing with underfloor heating as the wood is subject to a higher than usual temperature and degree of moisture loss.

Please use the following fact and figures to determine the suitability of use of Chauncey’s Tectonic Engineered boards. We have further information on our Chauncey’s Blog about the importance of house climate when using wooden flooring over UFH. Please note that it is important to keep relative humidity in rooms within the range of 40%- 60% RH.

ENGINEERED BOARDS

For use over underfloor heating we would always recommend Chauncey’s TECTONIC™ engineered wide plank flooring – either in our ORIGINAL range or in our FSC range – or even in Chauncey’s specialist REGENCY AGED finish or in FRENCH RECLAIMED OAK.

TECTONIC™ flooring has a unique structure; layers of high-quality, water-resistant birch ply are glued together in opposing directions to form a base resistant to movement and finished with a kiln-dried, solid hardwood layer. 

You can choose to have either an overlay board of 15mm thick (11mm ply + 4mm oak wear layer)  or a structural thickness board with a total thickness of 20mm (14mm ply + 6mm oak wear layer). These TECTONIC™ boards give the appearance and the durability of a solid wide oak board, but also ensures even better stability than a traditional engineered board.  (see more details on the TECTONIC™ page).
The boards can be supplied unfinished, leaving you the opportunity to apply a lacquer or oil of your own choice, to produce a more natural looking floor.  We can also hand-finish these boards with lacquer or oil if a pre-finished board is required

TECTONIC™ flooring has been successfully used in many situations where different types of underfloor heating have been used and is extremely resistant to movement.  It is advisable to stack and acclimatise the boards as per our instructions to ensure the TECTONIC™ boards remain as stable as possible.  TECTONIC™ boards can be floated or glued directly to screed floors (using a flexible adhesive) or secret nailed to battens/joists (please see fixing below).

KILN DRIED SOLID BOARDS

We would always recommend engineered boards over UFH, not solid hardwood boards.  Once laid, Chauncey’s TECTONIC™ engineered boards look exactly the same as solid oak boards but will be much more stable.  If solid boards have cupped (due to over drying and contraction of the underside of the board, which can happen if UFH is inadvertantly turned up too high) there is no real remedy.  If you have to lay solid oak boards over UFH it would be best to use low constant-heat UFH rather than UFH that switches on and off several times a day

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Generally, the wider a board is, the greater the expansion and contraction of that board and so there is more likelihood of unwanted movement. Thus we would recommend that the width of solid oak boards used over UFH should be kept to a absolute maximum of 130mm.

Our solid hardwood boards are normally air-dried and then kiln dried to between 8 and 12% moisture content. We would not usually recommend further kilning as it can dry the boards too much and damage their structure. – and as explained before the moisture content of boards can not be ‘fixed’ – they will constantly respond to the amount of moisture in the environment. 

If you have to use solid oak boards (remember: the narrower the better) then we would recommend ‘loose laying’ the boards.  This means your fitter will lay the floor, cut it to size and simply push the tongue and groove boards together rather than fixing or nailing.  The floor can be lacquered or oiled like this and then used as normal (although it may squeak as the joints move).  The under-floor heating should then be GRADUALLY increased over a period of a couple of months until you reach the normal operating temperature of your underfloor heating.  This will gradually acclimatise the boards to the extra heat & moisture loss rather than the severe impact of extra kiln drying.  Once a normal heating temperature has been reached the boards can be taken up a few at a time and fixed either by gluing or nailing (see below).  However, seasonal variations and turning heating off in the summer months will still result in variable amounts of expansion and contraction in the boards.

FIXING THE BOARDS

We would recommend either secret nailing or gluing boards depending on the method of underfloor heating.  If a concrete screed has been used then gluing boards using either SIKABOND or Rewmar flexible adhesive is the best method to ensure a rapid heat transfer.
If battens have been laid, then the flooring can be secret nailed to this, but great care must be taken around any areas close to the pipes.  It may be advisable to use SIKABOND T2 glue (supplied in cartridges) to glue boards to any battens that are close to pipes to ensure that there is no damage to the pipes from nails. 

TECTONIC™ Oak Flooring can be laid as a ‘floating floor’ (i.e. where the T&G joints are glued together to form a floating  layer over the solid subfloor).  However,  this is not the best choice for installing over UFH as any air gaps left when installing ‘floating’ boards will act as barrier to the heat transfer.  If your subfloor is absolutely flat then floating may be a viable option using a specialist underlay which will aid the transfer of heat.
For more information on fixing Chauncey’s floors please look at the fitting diagram on our website or look at our YouTube film which outlines the best fitting method to choose.

GUARANTEES

It is advisable to be extremely suspicious of any ‘lifetime’ guarantees given with wooden flooring.  Inevitably, the condition of a floor depends on many factors, for example:

• how carefully the wood has been stored on site prior to laying;
• the condition of the subfloor;
• whether a DPM has been installed,
• how well the floor is laid;
• what finish is put on top of the boards;
• how well the finish is maintained;
• how much usage the floor receives etc.

In our experience the guarantees given by most flooring companies are usually fairly worthless once all the small print has been examined. 

At CHAUNCEY’S we rely on our good reputation – the majority of our business comes through word of mouth and recommendation. 
We don’t offer worthless guarantees, but we will do our utmost to keep our customers happy and in the unlikely event of a problem arising, we will always do our best to resolve it.