ᐅ Horizontal waterproofing of the foundation slab

Created on: 26 Jan 2017 20:54
J
joho78
Hello!

I’m interested in your opinion again.
In about one week, the screed will be poured (plumbers and electricians are currently busy). Now the following issue has come up:

- We don’t have a horizontal damp proof membrane on the slab (no basement) and the screed installer has pointed out that this apparently does not comply with the standards.

- We don’t have a horizontal damp proof membrane because the builder said it wasn’t necessary since we have a 40 cm (16 inches) capillary-breaking layer (Geocell foam glass gravel). This was also recorded in the contract protocol and the construction meeting minutes.

- The architect also confirmed the non-necessity with a building physics calculation, which is documented in the construction meeting minutes.

=> Our concern now is what, for example, the insurance company would say in case of a pipe leak. Could they refer to the standard and possibly reduce the payout in case of damage, even though the non-necessity was confirmed by our professionals?

Here is the structure again (as mentioned, no basement, so directly on the ground):

200 mm (8 inches) gravel
400 mm (16 inches) foam glass gravel (capillary-breaking)
200 mm (8 inches) concrete
110 mm (4.3 inches) EPS granulate
70 mm (2.75 inches) cement screed
10 mm (0.4 inches) tiles

What do you think? Should we definitely add a damp proof membrane?

Best regards
Jochen
N
Nordlys
22 Jul 2017 12:56
So, this is how it was done here. Concrete slab. On top of that, a bitumen membrane welded on with a gas torch. Then the cables and pipes. On top of that, insulation made from a type of expanded polystyrene, but significantly more compression-resistant. Over that, a foil, and on the foil, the heating pipes. Then the screed. The screed is separated from the walls by a blue foam strip. In the bathrooms, a waterproofing coating is applied on the screed. In the other rooms, a leveling compound is used—something from Mapei, as indicated on the bags. On top of that, either tiles or vinyl flooring; for vinyl, a kind of primer is applied in between, also from Mapei.
This construction method is actually standard here, although the material manufacturers are not always the same. Karsten