On which substrate do you install your wooden floor?

Everything starts with the substrate for your flooring. What type of underfloor you have, determines the technique and the materials that you use to install your floor.

i. Vinyl, carpet, cork, laminate and other soft or semi-soft surfaces

First, remove these floor coverings and then follow the tips related to the layer located underneath them.

ii. Sabulous clay

Installing wooden floors directly onto a sandy surface is not a good idea, because the in this way the wooden floor is directly in contact with the moist surface and this way your wooden floor is subject to the effects of soil moisture. Dig out the sandy surface and then place a plastic film that prevents moisture from penetrating. Then comes a concrete surface and then a screed, possibly with a floor insulation or underfloor heating. Please ask a specialist for advice.

After installation of your new subfloor, follow the guidelines that apply to it.

iii. Wooden flooring joists

Make sure that the joists are firm and completely level. In order to prevent the floor would bend too much, the maximum distance between the centres of two neighbouring joists should not be more than 40 cm.

Wooden floors of a minimum of 20mm thickness can then be placed perpendicularly to the joists and be nailed in the tongue. Thinner wooden flooring does not qualify for this installation technique.

iv. Wooden subfloor or OSB-panelling

Of course you can also install a sub-floor on the wooden joists. OSB boards are often used for this purpose. It is very important that they are applied on the joist structure firmly, stable and level.

One advantage of this technique is that you can decide in which direction you place the floor boards, because it is no longer necessary to lay the planks perpendicular to the joist. Moreover, you can now also choose a thinner type of flooring (15 or 10mm, depending on the thickness of the OSB), giving you more choices.

v. Existing wooden floor

Also on top of an old wooden floor you can put a new one. Just make sure the boards of the old floor are stable, level and smooth, firmly attached and not damaged by insects or signs of moisture or mould.

Install the new boards at right angles to the old boards. Here it does not matter what the thickness of your floor is.

vi. Existing tile floor

An engineered floor can be installed on top of an existing tile floor or other hard or glassy substrate (e.g. Ceramic tiles, enamel tiles, polished marble, natural stone). That's a better solution than removing the tile floor first because you avoid the risk that the underlying pipes or screed are damaged.

Make sure that any loose tiles first cemented and stable, flat and level. It is best to apply a levelling agent.

If you want to glue your wooden floor to the tiles, it is best that you roughen the tile surface first, so the parquet adhesive adheres better to the tiles. This roughening can be done with a diamond blade. You can instead also choose to use an adhesion promoter. That will save you some work.

vii. Anhydrite subfloor

Anhydrite is a self-levelling floor screed, based on plaster. This screed technique is now increasingly used. To successfully install a wooden floor on this type of surface, you should pay attention to a number of elements:

  • Determine the moisture content of the screed with an electronic moisture meter or a calcium carbide bottle. The anhydrite screed may contain up to 0.5% of moisture. (If the floor is combined with underfloor heating the anhydrite surface should contain also┬áno more than 0.5% moisture.) If this moisture content is higher, you have to let the substrate dry out.
  • If the surface is sufficiently dehydrated and in optimum condition you can now start with the floating installation of your floor.
  • Would you like glue the floor to the substrate, then you take a few extra measures:
    • When the anhydrite has dried a thin layer of calcium sulphite is formed on the surface of the floor which is detrimental to the adhesive bond and, therefore, has to be sanded. You can do this by using a coarse sanding disc with titanium or diamond grit.
    • The dust released after the sanding of the floor impedes a good adhesive contact. So vacuum thoroughly after sanding.
    • Furthermore, it is recommended to improve the adhesive bonding additionally with a primer suitable for anhydrite.

viii. Sand cement subfloor

Also when dealing with a sand cement screed you should make sure that it is fully dry and in good condition before you begin the installation of your floor. The exact determination of moisture content should be done with an electronic moisture meter or a calcium carbide bottle. For cement, the maximum moisture content is 2.5%. (If you combine the floor with underfloor heating it is maximum 1%.)

You can then proceed with a floating installation of your floor or glue it to the subfloor.