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What has to be done to a floor before you can lay a wooden floor on it? If you do not properly prepare the underlay, then you are guaranteed to encounter problems with your wooden floor later on. But first you must choose:
Is it a new building or a renovation?
Are you removing an existing floor?
Will you be laying a wooden floor on top of an existing floor?
Determine thickness: make sure you know the thickness of the finished floor so the chapist can pour the screed to the right level.
Start properly: choose a good professional. He or she will always lay PVC sheeting first, to hold back rising damp from the ground. Even above the ground floor! In addition, ask for a reinforced screed. Then they will add a special product, or incorporate gauze to make everything even stronger. If you are considering doing this yourself, remember that pouring screed is work for skilled professionals. It has to be very smooth. It is a craft in itself.
Patience is a virtue. But how long should you wait? You can expect to wait for one week per centimetre, to 5 cm thickness, but that varies. A screed above 5 cm takes about 2 weeks per centimetre to dry. (eg a 8 cm thick screed, you can count 12 weeks). Thick screeds dry more slowly. But waiting is crucially important. For a screed without underfloor heating, there must be no more than 2.5% residual moisture. For a screed with underfloor heating, no more than 1.8%. You have to measure this with a moisture meter. But you are actually better off having a professional do this too.
Finally, make sure that the area is well ventilated. This helps speed up the drying process. But do not use a hot air blower! This will create condensation, and therefore mould. You have to open the windows. Even in the winter. You can only turn the heating on after a minimum of four weeks, but even then there must still be a draught.
In short: have the screed poured by a professional and ask your parquet installer to measure the moisture content via the CM method.
Then there are three possible scenarios:
The screed is not damaged and there is foil under it: you can lay the wooden floor straight away.
The screed is not damaged and there is not foil under it: you must apply an epoxy layer on the screed to block rising damp. After that, you can lay the wooden floor.
The screed is damaged and there is foil under it: you have to level it. To do this, you need to use a selflevelling compound. It is a self-flowing product, but you still have to spread it with a spatula, and it dries quickly. If I were you, I would ask a professional to do this.
This is also an option, as long as there are no loose tiles. You first have to degrease the surface properly, then roughen the floor with a diamond disc, and finally always apply an epoxy layer to block moisture from the ground. You can then lay the wooden floor normally.
Our experts are ready to help you with free advice. Don’t hesitate to contact Pieter and his colleagues by email or telephone.
