Nails through sealing membrane in the basement

So according to what I have researched, this foil on the floor slab does not protect against rising damp, but at most against water vapor diffusion. The sealing on the floor slab should not be damaged, but occasional penetration by such nails or dowels could probably damage a bitumen membrane. A foil sealing is generally more sensitive and such penetrations should be sealed again afterwards. However, in practice, such things are seen very often and are regularly not criticized (also by expert surveyors).

I will also send this to my expert. I would still be happy to hear from the OP about what has come up for him.

I’ll also send this to my expert. I would still be glad to hear from the OP what has come up for him.

Hi, I only have the information that it is apparently common practice, even if strictly speaking it should/should not be like that ....

Hello,

this is a vapor barrier, not a waterproofing barrier. Bitumen is elastic and sticky; if you drive a nail through it, there is no gap between the nail and the bitumen. And even if there were, the amount of vapor that could theoretically diffuse through is so minimal that it certainly won’t harm the insulation of the underfloor heating.

The purpose of the vapor barrier is to prevent ascending diffusion, or to reduce it so much that diffusion toward the interior is always faster from above than from below, thus preventing moisture accumulation.

All is well.

Best regards

Only the OP does not have a bitumen waterproofing, but a plastic one (Katja?). It would be interesting to see how it behaves there...

Hello,

oh, my mistake, I overlooked that. I still stand by it. Due to the penetrations, so little diffusion will take place that diffusion always occurs faster upwards. Thus, no trapped moisture can form. The foil does not help against pressing water anyway, that is not its purpose.

Best regards