ᐅ Vapor retarder on screed in the attic?

Created on: 13 Oct 2021 09:43
S
Scout
S
Scout
13 Oct 2021 09:43
Hello,

our attic is going to be converted. We have a cement screed that has been left exposed for three years now. Floorboards will be installed (not glued).

Is a vapor retarder absolutely necessary here? Or can we start directly with the impact sound insulation?
KlaRa13 Oct 2021 11:56
Hello questioner.
If the floorboards are to be installed (screwed/nail­ed) on battens, you only need to ensure a sufficient edge gap for ventilation.
If the floorboards are to be laid on a screed surface (previously leveled with a suitable compound), or if there is a bathroom below the attic, a vapor barrier (PE foil, at least 0.15mm thick, overlapped at the seams and extended up the sides to the top edge of the floor) should definitely be used.
Good luck: KlaRa
S
Scout
14 Oct 2021 11:17
Hello and thank you.

Does it make a difference if the floorboards are clipped, meaning they are not fully bonded to the subfloor? I am using 3mm (0.12 inches) thick corrugated cardboard as impact sound insulation, with the floorboards installed on top. There is a bathroom directly below, and according to the floor plan, another bathroom will be built directly above it.
KlaRa14 Oct 2021 12:23
You wrote: "the attic is going to be converted in our house."
Then you continued: "... but directly above in the floor plan, another bathroom is planned."
Here, there is inevitably a misunderstanding, because if the attic is being converted, another bathroom cannot be located above it (since the roof structure is above).
Furthermore, when it comes to moisture from a screed, how the parquet flooring elements are joined together later is irrelevant.
Once again: When installing parquet flooring directly on a screed (without battens), a vapor barrier must be used!
Best regards, KlaRa
Tolentino14 Oct 2021 13:14
No, he means that in the attic there is a bathroom planned exactly where the bathroom is located in the floor below.
The question is, is parquet flooring planned there (in the attic) despite the bathroom?
On the other hand, since waterproofing is required in the bathroom anyway, he can probably skip an additional vapor barrier?
S
Scout
14 Oct 2021 13:17
There is already a bathroom on the upper floor. The attic above is planned to have a bathroom in the same location later on. Currently, only the drywall partition walls have been installed upstairs; the attic bathroom will be added after the floorboards are laid. For now, the bare screed remains there.

Everything else is intended to be a room (studio), which will be covered now. OK, so a vapor retarder must be installed over the dried screed first, then the impact sound insulation, and finally the floorboards.