Cracks in new floor screed

laragh

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There are a few cracks in my new floor that has been laid in my new house.
The screed is a sand+cement mix laid to a depth of 80 MM throughout the house. It was let cure naturally for about six weeks before the underfloor heating went on. When the heat was put on it was built up slowly over a week (as recommended).
The heat is now on 3 weeks and there are a number of cracks in the floor. These are mainly at door openings and would stretch accross the width of the door. The cracks would be about 1 - 2 MM wide although there are one or two wider ones.
There is also a fairly wide crack (3- 4 MM) at a joint where one days flooring was completed and the next days started.

Should I be filling these cracks before tiling/ wooden floors are started?
If so, how should I fill them?
Would a dry sand cement mix swept into the cracks be OK?
 
Try squegeeing a slurry of floor levelling compound into the cracks, it's flow and workability will suit the job better than sand/cement.
 
Thanks for that Carpenter!

One question- how does this floor levelling compund react when subject to heat from an underfloor heating system?
 
Levelling compound dries very quickly, it has some additives in addition to its cement content to enhance its properties. I wouldn't forsee any problems as long as the temperature wasn't too high.
 
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