ᐅ Water is present on the foundation slab or waterproofing membrane.

Hello,
here is our situation regarding a new construction project:
To apply the bitumen waterproofing membrane together with the insulation foam at the base of the building, we, as the clients, dug a small trench on the north side at the request of the builder. Apparently, there was too much concrete recycling material from the construction road there, and the site worker was not able to dig the trench quickly enough... anyway.
Now the work is done and the small trench is still there.
When it rains heavily, the trench currently fills up with water (gutters and downpipes are already installed, but the soakaway including rainwater drainage has unfortunately not yet been put in place). Water cannot be properly drained from the downpipe because the terrain slopes upward at the back of the lot, and the clay soil does not allow for digging the necessary gradient into the ground. The water then stands just below the insulation foam. An image is attached.
I am now wondering whether standing water pressing against the foundation slab could be harmful, both underneath the insulation foam and, in extreme cases, on the foam itself. Also, would it be better to leave the trench as it is for now or to fill it back in up to the bottom edge of the insulation foam before the next heavy rainfall?
What are your thoughts?

Best regards

vorkalmatador schrieb:

at the request of the developer

And if the developer wants you to build the walls up, will you do that too? You are probably paying a lot of money for your house, so don’t let the developer take advantage of you. They should coordinate the trades so that the work is done properly.

vorkalmatador schrieb:

I am wondering whether standing water pressing against the foundation slab is harmful, both under the polystyrene and, in extreme cases, even on the polystyrene itself, and whether it would be better to leave the trench as it is or to refill it before the next rain until the bottom edge of the polystyrene.

I would first check if the material used is suitable for that purpose. In my opinion, XPS or a similar product is normally used there. Polystyrene absorbs water.

The front is actually 1.5m (5 feet) away from the concrete recycling construction road, but unfortunately some material has been tracked in by the traffic. There’s nothing the developer can do about that, but I understand what you mean. Whether it is polystyrene or another material, I can’t say for sure. I will look into it.