Can I lay tiles on a fresh screed?
Next week the screed will be laid in the new building. Up until now, I thought it had to dry for at least 6 weeks before the tiler could get to work. Now the contractor says it can be done as soon as it's ready to be walked on, and that the tiler can start right away, and we have to take care of getting the tiles.
That is, either immediately or in 6 weeks. Where's the logic in that and how can the screed dry if there are large tiles (60 x 60 cm) on it?
Answers
It doesn't have to dry for 6 weeks, it has to dry for x weeks and then the residual moisture is measured. Each room should have a small hole in the middle with a plastic wand, that's where you take the measurements.
There are additives that make the screed dry faster (very fast).
I would also consider the following:
The screed should not lose moisture too quickly, such as at the top, so it doesn't "sand" (my layman's understanding). If the tiler "wants" to work only with difficulty in the "haze" and plows all the windows, the screed may be laid unfavorably and unevenly.
If necessary, negotiate with the tiler that only the windows in the appropriate room will be open, but not the windows across the hall to avoid cross ventilation.
The tiler will measure the residual moisture and proceed only if it meets the requirements.
Are you sure no quick-drying screed like anhydrite screed has been laid?
It is correct to say that wet screeds can only be laid after determining that they are ready for laying (in this case because they have dried out). It is the task of the floor layer or, if a screed with additives was used, the task of the screed layer to indicate HOW the residual moisture content of the screed should be measured and at what value the screed is ready to be laid.
There are screed additives that deliver on the manufacturer's promise. This means that it is quite possible that the screed will be ready to be laid in a few days. In the case of some additives, it even happens that once the screed is established ready to be laid, the screed must be laid immediately to eliminate the possibility of re-wetting. This is rare, but it exists!
