About dilatation

The heating screed, under the influence of the heating, expands by 5 to 10 mm, depending on its size. With inside insulation, the load-bearing screed, and particularlty the walls are in the cold and thus do not follow this dilatation, that is why a dilatation joint must be put placed all around the heating screed, so as to prevent this one from not pushing the walls which would crack, because the dilatation pressure is huge.

With outside insulation, this problem does not existe because the walls are almost at the same temperature than the heating screed. The joint is nevertheless placed, but there is no risk if its thickness would have been badly estimated, or in case it would have been badly set up.