ᐅ Roof Insulation for KfW70 Energy Standard House – Concerns About Moisture Damage

Hello everyone,

I have a question regarding our roof insulation.
We are currently building a KfW70 single-family house.

I heard that the internal insulation should be built up like this:
drywall -> vapor barrier -> mineral wool -> roofing membrane -> roof tiles

We have double insulation installed. It is built up like this:
drywall -> mineral wool -> vapor barrier -> mineral wool -> roofing membrane -> roof tiles

I have now noticed that the mineral wool on the first insulation layer, right next to the vapor barrier, is damp. It looks like condensation from the inside. The building is still drying out.

Can you tell me if this setup is correct?

Thank you

Hello,
Moisture in the insulation layer is never acceptable. The overall construction is fundamentally sound.

What exactly is the layer structure?

Regards

hi,

from inside to outside:

gypsum board -> Isover mineral wool (exact type unknown) -> blue PE foil -> Isover mineral wool (exact type unknown) -> Catop XL SK vapor-permeable membrane -> roof tiles

thanks

Hi,

I actually wanted to know how thick the different insulation layers are...

I think it’s the construction moisture. Either it’s already so cold at the vapor barrier that the moist air condenses, or you have so much moisture in the room that the air is saturated. And nothing can diffuse out because of the vapor barrier.

So, ventilate and heat a lot.

Regards