October 10, 2024, 11:19 am | Read time: 5 minutes

Does the old flooring need to be replaced? Before the new floor can be laid, the old subfloor must be prepared. This article reveals which steps are necessary.

Is it absolutely necessary to prepare the floor before laying new flooring?

There are only a few cases in which this work could be omitted, such as tiles that are still firmly bonded to the substrate. However, flooring manufacturers do not usually recommend this. It should also always be borne in mind that an additional covering automatically raises the floor, which can lead to doors no longer closing properly and having to be shortened accordingly.

When it comes to floor coverings that have to be fully bonded to the subfloor, manufacturers only provide a guarantee if the floor has been prepared according to their specifications. It is, therefore, better to actually carry out the preparatory work.

Why preparation is important

A subfloor that is not optimally prepared is noticeable in various ways. The following reasons speak in favor of preparing the floor before installation.

• Unevenness will show through on vinyl floors. This ruins the smooth appearance.
• This also applies to holes in the old flooring. Depending on their size, they give the impression of sinking into the floor when walking.
• Any unevenness will put the joints under tension if the flooring is clicked together. As a result, these can come loose.
• Moisture in the old flooring can cause the covering to swell, and mold can form.
• Adhesive does not adhere properly, and the new flooring is only loose in places.

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This work is necessary for preparing the floor

For a convincing result after laying a new floor covering, the same steps must always be carried out. It doesn’t matter what material the new floor is made of.

1. Remove the old floor covering

The first step is to thoroughly remove the old floor covering. Of course, depending on the material, this may involve more or less effort. However, thorough means that the old floor covering has actually been completely removed. This also applies, in particular, to adhesive residue from tiles or carpets.

When removing old ceramic tiles, it is almost inevitable that more or less minor damage will occur. These are removed in a later step.

2. Sanding the floor

Once the old covering has been removed, the substrate is sanded flat. A floor sanding machine (which is also available for hire) is used to remove old adhesive residue, filler, or other unevenness when preparing the floor.

Using such a machine always looks easier than it actually is. So first of all, approach the job carefully. As adhesives, in particular, are not usually harmless, it is advisable to wear a dust mask while sanding.

3. Inspection and possible sanding

After sanding, the surface should be absolutely even and look that way. However, even the most powerful sanding machine can reach its limits. Some tile adhesive residues can only be removed with a chisel.

4. Vacuum the substrate

The next step is to clean the surface with a workshop vacuum cleaner. This thoroughly removes sanding dust and other particles.

Caution: The usual household vacuum cleaner is not suitable for this work. The sanding dust is so fine that the filters in a simple vacuum cleaner become clogged more or less immediately. In the worst case, they become permanently unusable, or the appliance is damaged. You can also hire a workshop vacuum cleaner, which can also be used to clean the garage or cellar.

5. Priming

In this step, a so-called barrier primer is applied. It prevents moisture from seeping through from the floor. It also compacts the floor and binds dust residues from the previous steps.

Note: When purchasing, it is best to look for low-emission products. This contributes to a better indoor climate and health. It is also important to adhere to the drying time. A little patience is therefore required here.

6. Leveling

This step is optional when preparing the floor. Whether it is necessary depends on what damage the removal of the old flooring has left behind. If there are many visible irregularities, it will take far too long to fill them by hand.

This is much quicker with floor-leveling compounds. These are fluid and flow into the depressions so that the end result is a uniform appearance. The building material levels itself by flowing.

Depending on the nature of the substrate, it can be used either selectively or over a large area.

Caution: If the entire floor is treated with the leveling compound, it is essential to apply edge insulation strips around the surface beforehand. This material has two functions. Firstly, it interrupts the direct contact between the floor and the wall. This prevents or hinders the transmission of sound between the floor and the wall. This means that footfall sound cannot simply resonate through the wall when people walk on it.

In addition, the leveling compound expands slightly as it dries. The edge insulation creates the necessary space for this. This prevents stresses in the flooring that could later lead to cracks. Once the compound has dried through, the floor is finally ready for its new covering.