ᐅ Interior plaster on exterior wall not fully applied

Created on: 19 Aug 2019 18:13
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Platzhirsch85
Hello everyone,

We are currently having a house built by a general contractor (external wall structure: aerated concrete - mineral wool - brick veneer). At the moment, the plasterer is working inside (walls are being coated with lime-cement plaster). Some pipes run surface-mounted in room corners and are planned to be later covered with drywall panels (e.g., flue pipe for the gas heating system).
Currently, there is no plaster behind these pipes. The aerated concrete is visible (see photo).

So far, I have assumed that the internal plaster forms the airtight layer on the external walls. For the same reason, socket and switch boxes in the external walls were fitted with airtight membrane boxes. This seems to be counterproductive if large areas behind surface-mounted pipes lack internal plaster. In my opinion, the drywall cannot take over the function of airtightness, can it?

The issue of plastering walls behind pipes probably exists on almost every construction site. How is this usually resolved?
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Bookstar
20 Aug 2019 19:33
To be on the safe side, I would simply cover it thoroughly with dirt.
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guckuck2
20 Aug 2019 19:47
Is dirt the new expanding foam?
B
Bookstar
20 Aug 2019 21:21
In our everyday language, we use this term for anything that is roughly spreadable, such as plaster and mortar.
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Platzhirsch85
20 Aug 2019 21:24
These Wedi boards seem to me to be a viable solution.
We have a similar issue in another area, but there, manual re-plastering is not 100% feasible. Therefore, re-plastering cannot be the sole solution.

The plasterer suggests installing a vapor retarder inside the boxed-in area. However, it is questionable how well this can be attached to the plaster.

If the joint edges between the Wedi boards and the plastered wall are properly jointed, then doesn’t this create the airtight layer?
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Nordlys
20 Aug 2019 21:53
Just apply an acrylic sealant bead along there, and it will be sealed.
wrobel21 Aug 2019 07:11
Hello

That still won’t be enough.
The waterproofing to the ground floor and to the membrane behind the drywall is still missing.


Olli