ᐅ 42.5 cm aerated concrete and 400 cm wide windows with external venetian blinds
Created on: 23 Jan 2025 16:32
S
Steffen_S
Hello everyone,
We hope to start our single-family house construction project this year. We are building a single-story house, and I would like to build monolithically with 42.5 cm (17 inches) aerated concrete, so without additional thermal insulation.
My father is very involved and, as an experienced "construction phase" person, he is quite skeptical because for him only 36.5 cm (14.5 inches) hollow brick with external thermal insulation system (ETICS) comes into question. He sees many problems with the roller shutter / venetian blind boxes in connection with thermal bridges and plaster cracks.
I would like to better understand this topic and have done some research with the following results:
42.5 cm (17 inches) thick wall, with two fixed glazed windows of 400 cm x 250 cm (157 x 98 inches).
Right above the window, one can install, for example, pre-insulated venetian blind boxes. These are (if I understand correctly) exactly 42.5 cm (17 inches) deep and insulated. The maximum width of up to 500 cm (197 inches) seems to fit – does anyone know if these are really custom-made in 400 cm (157 inches) lengths, or are we talking about 2 x 200 cm (79 inches)?
A = 42.5 cm (17 inches)
B = 29.0 cm (11.5 inches)
It seems there are no ready-made, load-bearing aerated concrete lintels for spans over 4 m (13 ft).
Since we are building only a single story and the timber flat roof will rest directly on the wall at the top, could one then use aerated concrete U-blocks (42.5 cm (17 inches) deep, 49.9 cm (20 inches) wide) to make a ring beam, which in the area of the window openings would simultaneously serve as a lintel?
This way, you would ultimately avoid material changes—except in the area of the venetian blind boxes.
You would still embed reinforcing mesh across these transitions anyway to prevent plaster cracks caused by different material expansions, correct?
Thanks for some explanations—I just want to better understand the whole topic.
We hope to start our single-family house construction project this year. We are building a single-story house, and I would like to build monolithically with 42.5 cm (17 inches) aerated concrete, so without additional thermal insulation.
My father is very involved and, as an experienced "construction phase" person, he is quite skeptical because for him only 36.5 cm (14.5 inches) hollow brick with external thermal insulation system (ETICS) comes into question. He sees many problems with the roller shutter / venetian blind boxes in connection with thermal bridges and plaster cracks.
I would like to better understand this topic and have done some research with the following results:
42.5 cm (17 inches) thick wall, with two fixed glazed windows of 400 cm x 250 cm (157 x 98 inches).
Right above the window, one can install, for example, pre-insulated venetian blind boxes. These are (if I understand correctly) exactly 42.5 cm (17 inches) deep and insulated. The maximum width of up to 500 cm (197 inches) seems to fit – does anyone know if these are really custom-made in 400 cm (157 inches) lengths, or are we talking about 2 x 200 cm (79 inches)?
A = 42.5 cm (17 inches)
B = 29.0 cm (11.5 inches)
It seems there are no ready-made, load-bearing aerated concrete lintels for spans over 4 m (13 ft).
Since we are building only a single story and the timber flat roof will rest directly on the wall at the top, could one then use aerated concrete U-blocks (42.5 cm (17 inches) deep, 49.9 cm (20 inches) wide) to make a ring beam, which in the area of the window openings would simultaneously serve as a lintel?
This way, you would ultimately avoid material changes—except in the area of the venetian blind boxes.
You would still embed reinforcing mesh across these transitions anyway to prevent plaster cracks caused by different material expansions, correct?
Thanks for some explanations—I just want to better understand the whole topic.
Harakiri schrieb:
Regardless of everything else, this is not necessarily correct – the U-value of a wall with insulation changes almost linearly with the corresponding thickness of the insulation layer. As I mentioned, I’m not a professional, but I remember the various calculation models we worked on with our engineering firm. Since we had abundant access to insulation, we could have increased it almost indefinitely. In this context, I recall their statement and the calculation models showing that doubling the amount of insulation would not lead to a doubled insulating effect linearly; otherwise, we would have done that.
As I said, I cannot substantiate this qualitatively, only quote it, and I’m not trying to convince anyone; to me, it sounded plausible, and I followed that approach.
ypg schrieb:
The original poster is now just a guest and has deactivated their account. Certain aspects of interpersonal behavior can’t be bought—you either have them or you don’t. Unfortunately, the number of participants unwilling to hear any opinion other than their own and only expecting applause is increasing. I think the OP was mainly looking for stronger arguments against his older relative to better justify a decision he had already made; that’s why the other options were presented in a rather negative context. I would appreciate it if people always shared their entire project here instead of playing childish hide-and-seek games. Apparently, not everyone is aware that they are free to build anything the forum might even dismiss as nonsense. Why shouldn’t I want to hear criticism that might point out mistakes before such a major life project? I have no understanding for that attitude but do encounter it in my immediate surroundings in other areas as well; asking questions seems to have become a sign of weakness nowadays—in many cases, people just assume they know better (not universally!). It actually reassures me when I can ask someone who might know.
As the saying goes: “You are an adult when you do something even though your father (mother, other adults, professionals) told you not to.”
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