ᐅ Sealing the basement floor with a welded waterproofing membrane

Hello experts,

we are planning to install the insulation beneath the screed ourselves. This is to reduce costs and ensure a "clean working method through own labor."

Now a question: In the basement, a waterproofing membrane will be applied to the floor. We still need to run a water pipe through the basement corridor. Should the waterproofing membrane be installed under the pipe, or should the pipe be laid on top of the membrane?

Thanks and best regards,
Christian

On the roofing membrane. If you want to do it absolutely perfectly, bond the water pipe to the roofing membrane using bitumen strips, not with perforated tape.

Hello Christian.
The correct position for laying the waterproofing membrane has already been explained by "does02."
If there are no other installations on the covered raw floor slab (in my professional experience, this can be different), then run the pipe parallel and close to the wall.
The problem otherwise arises with the insulation, which would have to be cut out if the pipe runs across the room.
You did not specifically ask about how far up and how to secure the waterproofing membrane along the walls, but I believe you are clear about the procedure.
Best regards, KlaRa

Hello Klara,
Thank you for your reply. Could you please describe the lateral extension and the attachment?
How high should it be, and what should I do in the corners? Good luck

In this case, the waterproofing (which I assume here) is used to protect against moisture rising from the ground slab from behind. Other types of stress cannot be withstood by a waterproofing membrane that is not adhered to the raw floor.

The optimal solution would be to attach the waterproofing membrane laterally to the horizontal barrier. This refers to a bitumen sheet, usually installed in strips during construction on the second row of masonry as a capillary break. If a proper connection to the different building materials were made here, for example using "Triflex BWS," this would create a transition truly compliant with the current state of the art.

However, the bitumen sheet is often missing.

In that case, the waterproofing membrane should at least extend several centimeters above the finished floor level and be fixed there with a narrow clamping strip (to ensure a firm hold against the wall). The downside is that if there is a lot of moisture in or under the ground slab, in the worst case, without a horizontal barrier, moisture could rise through the cross-section of the wall plaster and be released into the indoor air.

"There's no need to panic," as the saying goes. The edges of the membranes on the raw floor must be tightly sealed with suitable sealing tape. Otherwise, the whole effort is pointless!!

Good luck: KlaRa