What is the condition of your subfloor?

For optimal results for your new flooring it is very important that the subfloor is dry, even, firm and clean.

i. Dry

With an electronic moisture meter, available at most DIY Stores, the humidity of the substrate can be checked before you install your wooden floor.

If you are unsure about the residual moisture in the subfloor or if there is a chance that moisture can rise from the substrate, take precautions and install an extra polyethylene moisture barrier film.

For sand cement subfloors with a residual moisture content of up to 2.5% it is possible to use a vapour barrier primer.

ii. Even

For a perfect installation of your Lalegno floor it is essential that the subfloor is completely stable, flat and smooth. So check the subfloor thoroughly, especially when renovating.

Stable, flat and smooth, that means that no height differences occur between the different parts of the subfloor. With a straight rod of respectively one or two meters, you can determine the height differences that occur. Depending on the installation method and the substrate the differences per two meters should amount to maximum 3 to 6mm. Follow the guidelines in the table below closely for a successful result.

Subfloor

 

Floating installation

 

Nailed installation

 

Glued installation

 

(Semi)soft subfloor

 

Not applicable

 

Not applicable

 

Not applicable

 

Sabulous clay

 

Not applicable

 

Not applicable

 

Not applicable

 

Wooden joists

 

Not applicable

 

Per 1m:  max. height difference 5mm
Per 2m:  max. height difference 6mm

 

Not applicable

 

Wooden subfloor

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Per 1m:  max. height difference 2mm
Per 2m:  max. height difference 3mm

 

Existing wooden floor

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Per 1m:  max. height difference 2mm
Per 2m:  max. height difference 3mm

 

Existing tile floor

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Not applicable

 

Per 1m:  max. height difference 2mm
Per 2m:  max. height difference 3mm

 

Anhydrite subfloor

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Not applicable

 

Per 1m:  max. height difference 2mm
Per 2m:  max. height difference 3mm

 

Sand cement subfloor

 

Per 1m:  max. height difference 3mm
Per 2m:  max. height difference 4mm

 

Not applicable

 

Per 1m:  max. height difference 2mm
Per 2m:  max. height difference 3mm

 

If the surface is not sufficiently flat, in most cases that can be solved with a levelling agent.

iii. Firm

It is also important that the surface is sufficiently hardened and is firm.

The strength (surface cohesion) of the subfloor must be at least 0.5 N / mm². There are complicated measurement methods to determine whether screeds satisfy those requirements, but easier is to use a glue spatula or sharp object and scratch the surface. If parts of the screed come off the floor screed is not sufficiently firm and a reinforcement agent needs to be used.

Check the subfloor for cracks and loose parts. Fissures and cracks can usually be repaired or filled with suitable products. It’s better to remove loose particles and then fill the screed up again.

If you are faced with a screed that is crumbling or porous, it is best to use a special primer for weak subfloors. There are also primers which are specifically suitable for the reinforcement of cement or anhydrite screeds, both in the depth as well as on the surface.

iv. Clean

Before you start with the installation of your flooring, make sure the area is completely dust and grease free and that all traces of paint, glue, stucco, plasterwork, grease, oil, etc. have been thoroughly removed.