Solid Oak should NOT be floated. We do not recommend this as a fitting method for solid flooring. Battens or joints must be set at intervals designed to support header joints. The batten centre is dependent upon the grade of timber used. More support should be given to lower grade flooring. Battens must be a minimum of 36mm in depth to allow support. The very best method of fixing for solid flooring is by nailing to 18mm plywood. This offers all round support for boards.
When under-floor heating is in use, always try and move away from solid timbers and more towards engineered products if possible. Shrinkage can be a real problem over under-floor heating with sold flooring. Our advice is that solid flooring is not laid over under-floor heating. The extremes of temperature that it would have to face when the heating is switched on and off would cause real problems.
This method is usually done by using a secret nailed gun. The secret nail will be fired at a 45% angle through the tongue of the batten or ply substructure. When installing unfinished flooring over 130mm width, there will be a need for face fixing.
This can be done by screw or by pellet. The holes can be covered using a filler product.
There are some installations where nailing is not possible due to the height allowance, ie: 18mm ply and 22mm solid timer = 40mm build up. Where this is the case, a suitable adhesive will suffice. This will most probably require a trowel-down application. It is important to ensure firstly that the sub-floor meets the required moisture tolerances. Once this is established, it is then vital to make sure that the sub-floor is clean and free of any contaminants.
The sub-floor must be swept and free of dust.
When adhering solid wood floors to the sub-floor, it is important to work on small areas, no greater than 1m2 at a time. It may be necessary to clamp the floor as you go along the line; ensuring tension is kept at all times. It is advisable to face fix any boards in excess of 100mm width to restrict natural movement and avoid cupping problems.
Expansion gaps must be left for the floor to move and expand naturally. This must be calculated using the following formula:
1.5mm expansion x metre width = minimum expansion gap in mm
It is important to base the calculation on the width rather than length, as wood expands more widthways than lengthways. As a rule of thumb, it is always advisable to leave at least a 2mm 'washer' gap every 8 - 10 rows.