Roof gone, bitumen membranes applied and still water ingress

Hello everyone,

We are in the middle of an extension with timber frame construction on a solid house.
In other words: the roof structure is gone, the walls and two chimneys have been dismantled, and the flat, bare concrete ceiling is exposed.
The construction company has now welded expensive V60 bitumen sheets and covered everything with tarps after the leveling strips were applied – as moisture protection.
Unfortunately, unsuccessfully.
In the depressions of the tarp caused by the already applied strips, huge pools of rainwater have formed. However, through other holes in the tarp, water has collected underneath on the bitumen sheets. These did not remain waterproof, so the masonry around the chimneys on the ground floor and also down to the basement has soaked up a lot of water. Now the question is how to proceed further. The company has set up two drying devices: "it will dry again."
The wall has turned yellowish, everything smells musty after a week now. Almost all interior walls are affected, also a wooden ceiling and part of a kitchen.
Shouldn't the plaster be completely removed here, etc.? How do we proceed from here?
Meanwhile, the upper floor and the roof are in place so that no new water can enter.

Best regards

Daniel

A V60 bitumen membrane is rather inexpensive (4€ per m²?) As a layperson, I see a high risk that this rather cheap welding membrane will fail, as happened to you. I consider this to be a major defect. Urgently find an independent building expert!

A V60 bitumen membrane is rather cheap (4€ per m²?)
As a layman, I see a high risk with a single layer that this rather inexpensive torch-on membrane will fail, as it did with you.
I consider that a serious defect. You urgently need to find an independent building expert!

Well, the coating cost us 2500€… Now we are left with damp walls. Thanks for the tip

Presumably, the contract was to keep the house dry during the construction phase. This was not achieved. A contract for work owes performance. 2500€ includes a little material and a lot of labor. Suitable for a temporary seal, but you (actually the contractor) were unlucky that there was heavy mold. He now has to fix that again. It may be that he will not do this voluntarily because his insurance takes it from the living, and if he pays for it himself, the project is a loss-making business. Therefore: call an expert.

Call an expert

I would do that too. Nevertheless, I would be optimistic that the interior of the house can be dried out again. It is not the first house to be dried out.