All wooden floors are beautiful but if you want to be certain your new floor stays that way make sure the installation is done right, especially when the sub-floor is new concrete.
Wooden flooring comes in a wide range of forms but the one thing they all have in common is that they are beautiful, low maintenance and hard-wearing. Solid wooden flooring is perhaps seen as the highest quality product but engineered wood offers the same look and feel but is more practical in terms of how it contracts and expands so is much more suitable for, say , a room with underfloor heating or a room subject to extremes of temperature, like a conservatory. Engineered planks are made of layers of real wood and also a layer of MDF or plywood so have much greater rigidity so are also better for larger rooms.
Whatever type of wooden floor you choose they can all be installed over a concrete sub-floor or concrete screed floor. However, the concrete must be completely dry before installation begins. A new screed floor can take up to a month to fully dry out, or even more, depending on its thickness and the temperature and humidity conditions of the room. Concrete slabs can take up to 2 months to dry out fully so do not be tempted to rush the installation. If you do you could end up with a warped floor.
But even old floors should be checked for moisture content because existing damp problems could also cause a problem with a new wooden floor if not dealt with before installation. It is almost always advisable (unless you live in a hot, dry climate) to use a damp proof membrane (DPM) over the concrete.
Most of the problems that occur after a wooden floor was been laid on a concrete sub-floor are due to poor preparation or installation so preparing the sub floor fully and installing correctly should avoid any problems. As well as being fully dry, the concrete should be level so, if necessary, use a self levelling compound. If you don’t think you are up to the job then get the help of a professional.
Don’t forget that there can also be problems with the wooden floor itself if it has become damp during storage so allow the wood to acclimatise to your room by storing it there for at least 2 days before installing it.
There are 3 main ways of fitting a wooden floor over concrete:
This is where the wooden flooring is laid on a special underlay which has adhesive on the upper side but otherwise no nails or separate adhesive are used.
Check which adhesive is suitable for the type of wooden floor you have chosen as some adhesives are only suitable for planks of certain widths.The adhesive needs to be a flexible adhesive to allow for expansion and contraction of the wood and it is applied directly onto the sub-floor and then the wooden planks pressed down firmly on top. Don’t forget to wipe off excess glue before it dries. Also remember to leave a 10mm expansion gap at the edges of the room, including in the doorways and leave the floor to set for at least 12 hours before walking on it.
Nailing a wooden floor over a concrete subfloor requires the use of wooden battens placed at regular intervals (on top of the DPM) to which the wooden floor is actually nailed.You will need to use a nail gun and the nails are usually driven through the “tongue” of each plank so that they are not visible once the “groove” of the adjacent plank is placed into position.
This method also requires a 10mm expansion gap around the edges of the room.