ᐅ Window reveal preparation before installation... skim coat?

Created on: 13 Apr 2020 13:22
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lin0r87
Hello everyone,
we are now about to install the windows… As far as I know, the window reveal must always be filled before installation. This has been done everywhere, but as a layperson, I’m not sure if this is correct..? My site manager tends to agree with everything and so does not have much expertise (a request for a replacement has been made).

From the picture, it can be seen that this was done only with cement mortar.
The exterior wall structure is: 1cm (0.4 inches) plaster (interior), 17.5cm (7 inches) Poroton brick, 16.0cm (6.3 inches) insulation, 1.5cm (0.6 inches) plaster (exterior).

Friends who have recently built their homes say that a smoothing coat must still be applied. Is that true, or would this work as it is (see picture) to ensure airtightness?

Innenansicht einer Baustelle: Backsteinmauer, Metallgerüst, Holzbauteile, Ziegelsteine auf dem Boden.
11ant15 Apr 2020 15:28
guckuck2 schrieb:

Sort of, since the internal membrane is glued against the reveal, which is also difficult without a smooth surface.

I agree – I asked here because I have also seen constructions with angles in ETICS systems, which would be a separate matter to discuss.
guckuck2 schrieb:

The same issue applies on the outside, as the Poroton bricks also have grooves there, where a membrane is glued.

Would you therefore recommend Poroton brick builders to choose a different type of brick around the reveal area?
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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guckuck2
15 Apr 2020 15:38
11ant schrieb:

Would you therefore recommend that builders using aerated clay blocks choose a different type of brick for the reveal area?

Why, if a smooth plaster finish can create a suitable base?

It is simply an additional step that is not really necessary with smooth masonry.

I would not complicate things further by mixing in other building materials.

However, I am not a civil engineer.
lin0r8729 Apr 2020 14:04
I have an update regarding the window reveals.... Everything seems to have gone well. An inspection took place and it was quite favorable in a positive sense.

The windows have now been installed.

Two-story house under construction with scaffolding, orange brick walls, roofing membrane, and safety netting.


Construction site with scaffolding and orange brick facade; a person is standing at the bottom right.


Construction site: two-story building made of red bricks with scaffolding, safety netting, and open entrance.


Multi-story brick building in shell construction, surrounded by metal scaffolding and ladders.
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guckuck2
29 Apr 2020 16:22
It’s hard to see on the phone, but isn’t the external waterproofing layer still missing? I don’t see any membrane, only foam.
lin0r8729 Apr 2020 18:08
guckuck2 schrieb:

It’s hard to tell on a mobile, but isn’t the external waterproofing layer missing?
No membrane visible, only foam.

That’s true!
I just checked with my installer, and he said that a sealing tape on the inside is sufficient, combined with proper foam sealing on the outside.
The reason is that any remaining moisture can escape between the foam and the sealing tape (inside) instead of being trapped.
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dab_dab
29 Apr 2020 20:57
That’s why, as far as I know, there are window connection tapes designed specifically for interior and exterior use. The exterior tapes are then more vapor-permeable than the interior ones.

That doesn’t mean it’s impossible otherwise; I can’t really judge that.