ᐅ Sealing the foundation slab before the roof is installed

Hello,

When is it common to waterproof the concrete slab from the top, I mean at what stage? The construction company plans to do this before the roof is installed. Is that a good approach? Won't rainwater then accumulate inside the house?

Regards,
Daniel

Hello,
I would have sealing done after roofing is completed and before the rough-in installation of electrical and heating systems.

Best regards

Thank you for your reply,
What disadvantages would I face if it happens beforehand?

If I understand correctly, he even plans to waterproof first and then build the partition walls on top of that.
That would basically be wrong, wouldn’t it?
But it would confuse me, since he is a guild master himself.

winnetou78 schrieb:
Thanks for your reply,
What disadvantages would I have if it happens beforehand?

If I understood correctly, he even plans to waterproof first and then build the partition walls on top.
That would basically be wrong, wouldn’t it?
But it confuses me, since he himself is a guild master.

Your wall(s) should be built on a bitumen-like damp-proof membrane, not directly on the concrete slab. In our case, these were individual strips. The waterproofing was then "welded" with a torch after the roof was installed. As a layperson, I couldn't see a significant difference between the strips and the final waterproofing.

He doesn’t do that. He probably also lays a black membrane under the interior walls and doesn’t place the blocks directly on the concrete, but then he will most likely apply a bituminous torch-on membrane in the traditional way. He can also do that on the roof. You just sweep out any small puddles. Maybe the roof truss manufacturer gave him a late delivery date and he wants to keep things moving. Karsten

There are some penetrations in the slab that cannot be sealed 100%. When it rains for several days, water accumulates on the slab and seeps under the waterproof membrane. It then remains trapped there for several months.
In addition, the slab is still damp. Why not allow it to dry out a bit longer?