How To Lay Oak Flooring On Concrete
Traditionally solid oak flooring was laid by simply sending a nail straight through surface of the boards, at even spacing into the floor joists below. Nowadays, thanks to the introduction of tongue and grooved boards, what is known as secret nailing or screwing is the preferred method. This process involves using a nail gun or power driver to send the fixing through the tongue of each board (at a 45 degree angle), into the sub-floor or joist.
As time has progressed the need to fit oak flooring into ever changing conditions has increased. One such area is laying an oak floor over a concrete sub-floor.
One method to overcome this, when laying a solid oak floor, would be using the above method of laying out battens. The solid oak flooring could then be simply nailed or screwed down. This method however can prove to be unsuitable to some as the battens can lose all important room height.
A more commonly used method nowadays is to glue down your oak floor using a flexible adhesive. When doing this it is vital that you choose a glue which has been made specifically for this job. The adhesive needs to be strong enough to keep your flooring in place, yet flexible enough to allow for some natural movement in the wood. When glueing down solid oak flooring onto a concrete sub floor, our recommendation is that you do not glue a board which is wider than 120mm. The wider that a solid oak board is, the more prone it is to movement and cupping. When glueing a wider board down, you are increasing the risk of problems occurring.
What do you do then if you want a wider board than 120mm, but you are planning on glueing to a concrete sub-floor? If this is the case, we would recommend opting for engineered oak flooring, rather than solid oak flooring.
From above, engineered oak flooring looks exactly the same as a solid oak floor. Our engineered boards consist of a 6mm top layer of solid oak, which is bonded to 14mm of Siberian Birch ply. This makes the boards a lot more stable and less prone to problems such as cupping. This enables you to use a more wider variety of widths when laying onto concrete.
A final option for laying over concrete would be to fit using the floating floor method. This method however is not recommended for use with a solid oak floor because of the reasons outlined above. Therefore an engineered is only suited for this process. The floating floor method simply involves laying your engineered oak boards, without any direct fixing to the sub-floor. For this, the floor quite literally “floats" over the top of the concrete, with the tongue and grooves glued together.
Whatever method you decide upon when laying oak flooring over concrete, it is vital that the concretes moisture level is below 4%. This can be done using a moisture metre.