Can expanding foam damage a dpm?

22 Oct 2012
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United Kingdom
Insulating the kitchen floor in an old house, dpm is down with insulation on top, but as the walls are no where bear straight leaving a few gaps here and there of 10-20mm.

Can these be filed with expanding foam before being screened? Will this damage the dpm?

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You mean the dpm is so tight it can't be made to touch the walls?

The foam shouldn't damage the dpm. Although you could trowel some mortar down there.

You will need an insulation upstand to thermally break the screed from the wall.

In any case leave the dpc slightly protruding up above the FFL, and tuck it under skirting boards.
Thanks, it will have edge insulation around the room with the dpc standing 50 mm above ffl, the dpc can be moulded to the little variances in the wall, the issues that it would be nightmare to trim the insulation to fit these little areas.

My only concern was hearing expanding foam can cause plastics to deteriorate and don't want to damage the dpm
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Just slop a weak mix of sharp and cement down there. Cheaper than foam. Ultimately any tiles/floor covering or skirting should cover these gaps.

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