ᐅ Base waterproofing of the slab edge – correct positioning of the waterproofing?

Hello everyone, (I know the forum cannot provide legally binding advice)

our house is built. Phew. An inspector came and criticized the base waterproofing of the slab (as shown in the photo in red and orange) – they said this violates DIN XYZ (13967?), and that the base waterproofing must run along the green line (directly on the concrete slab). However, they could not clarify whether we are in a grey area and it is still acceptable, or if it is definitely not allowed. The builder says that with our method, no rising groundwater will reach the wooden house – and that it is much cleaner and more practical to install this way.

Now my question: for a timber frame house (or any other type of house), where should the base waterproofing be installed: before or behind the insulation?
Could this cause us problems in the future?

Best regards

Some people come up with interesting ideas – of course, the base waterproofing goes behind the insulation. Keep it simple: ask your builder to provide the manufacturer and product for the base waterproofing system, and to show you a base detail or construction drawing from the manufacturer that illustrates their method.

Schischuh schrieb:

Where should the base waterproofing be applied on a timber frame house (or any other type of house): in front of or behind the insulation?

I agree with @Harakiri. The insulation belongs on or in front of the concrete slab, with the waterproofing applied in front of it. However, it is quite common—usually only around the window waterproofing—that the waterproofing is applied over the insulation if the insulation is already in place when the windows are installed.

At the base, only capillary inactive insulation material suitable for this purpose should be used, so the insulation can be placed behind the waterproofing. As you described, the waterproofing can be damaged or deteriorate over the decades due to plant growth and movements of stones or similar factors, allowing water to penetrate.

How severe this is, the building inspector will know better. I just know that it should be done differently.

And the then waterproofing in the base or basement area should also be applied doubly (?) and, of course, fully adhered over the entire surface. Often, the torch is only applied spotwise. If it fails at one point, water can get behind the insulation, but with full-surface adhesion, this cannot happen.

But... Why pay an inspector if they can’t determine whether the damage is serious and needs immediate repair? They can’t just say, “It’s not done properly, but I don’t know if it really needs to be replaced now,” can they?! They present themselves as experts...

What has become of this topic? We have exactly the same situation. The foundation was constructed as a waterproof concrete slab, and a horizontal damp-proof course is in place. However, a vertical damp-proof course has not yet been applied and is planned to be installed from the outside onto the insulation of the slab and then extended upwards. The expert says this is highly unusual and, to his knowledge, not permissible. We have been waiting for about 3 months for the technical approval documents, which the site manager and construction company have yet to provide.

unitist schrieb:

What happened with this topic? We have exactly the same situation. The foundation was made as a waterproof concrete slab (WU slab), and a horizontal damp-proof course is in place. However, a vertical damp-proof course has not yet been installed and is supposed to be applied from the outside onto the insulation of the foundation slab and then extended upwards. The expert says this is very unusual and, to his knowledge, not permitted. We have been waiting for about 3 months for documents regarding the building approval, which the site manager and the home builder have yet to provide..

In our case, the ball is still in the home builder’s court...