Hello everyone,
I have already read and searched around a bit here, but I am still not quite sure.
We are planning to build a house. It will be a semi-detached house. We have been offered a house with 36.5cm (14 inches) aerated concrete exterior walls without additional insulation. The interior walls are also planned to be made of aerated concrete. Soundproofing boards are to be installed between the wall and the neighboring house.
I have to admit that I am quite a layperson and am slowly working my way through the very conflicting statements and information. We don’t want to build a passive house, but it should be future-proof and reasonably designed. Overall, I would like to aim for a kfw70 house, but that is not solely about insulation...
I have read various information about aerated concrete, clay blocks (Poroton), and also about prefabricated walls. I find it interesting that the U-value of the prefabricated walls is apparently significantly better than that of comparable solid walls (without additional insulation). However, I can’t really grasp what a difference of 0.1 W/(m²K) actually means in reality... I lack the practical understanding of this.
What I think I know:
- Aerated concrete can be installed without additional insulation. But is it any good!? Does it only just meet legal requirements, or is it also sensible to build this way?
- Aerated concrete has poorer sound insulation compared to sand-lime brick or clay blocks. This could be a problem especially for thin interior walls.
- Regardless of what I build (even without extra insulation), a controlled mechanical ventilation system is highly recommended because the houses are very airtight.
- Aerated concrete has poor thermal insulation properties in summer (I still don’t understand why a material supposedly insulates well in one direction – during winter – but not in the other – summer –?!).
- I have often read that the costs of adding extra insulation to a wall do not pay off over a reasonable period (in terms of heating savings – of course this also depends on the heating technology).
Could you help me clarify where I might be wrong? Why is sand-lime brick usually recommended for interior walls instead of aerated concrete? Soundproofing? Less crumbling when drilling? Price?
On the website of the well-known aerated concrete manufacturer, I read that they also achieve low U-values (below 0.2). But these blocks are then less stable, significantly more expensive, and worse in sound insulation... So can you really generalize about aerated concrete or do you need to specify the exact type of block? My supplier only talks about 36.5cm (14 inches) blocks. So I don’t really know which will actually be used... I should probably ask.
Is omitting additional insulation really the “state of the art” and reasonable (does it not pay off in heating costs) or just cheap?
As I said, I don’t want to build a passive house but an economically sensible concept.
Which wall structure would you recommend and why under the above conditions?
Thank you!
I have already read and searched around a bit here, but I am still not quite sure.
We are planning to build a house. It will be a semi-detached house. We have been offered a house with 36.5cm (14 inches) aerated concrete exterior walls without additional insulation. The interior walls are also planned to be made of aerated concrete. Soundproofing boards are to be installed between the wall and the neighboring house.
I have to admit that I am quite a layperson and am slowly working my way through the very conflicting statements and information. We don’t want to build a passive house, but it should be future-proof and reasonably designed. Overall, I would like to aim for a kfw70 house, but that is not solely about insulation...
I have read various information about aerated concrete, clay blocks (Poroton), and also about prefabricated walls. I find it interesting that the U-value of the prefabricated walls is apparently significantly better than that of comparable solid walls (without additional insulation). However, I can’t really grasp what a difference of 0.1 W/(m²K) actually means in reality... I lack the practical understanding of this.
What I think I know:
- Aerated concrete can be installed without additional insulation. But is it any good!? Does it only just meet legal requirements, or is it also sensible to build this way?
- Aerated concrete has poorer sound insulation compared to sand-lime brick or clay blocks. This could be a problem especially for thin interior walls.
- Regardless of what I build (even without extra insulation), a controlled mechanical ventilation system is highly recommended because the houses are very airtight.
- Aerated concrete has poor thermal insulation properties in summer (I still don’t understand why a material supposedly insulates well in one direction – during winter – but not in the other – summer –?!).
- I have often read that the costs of adding extra insulation to a wall do not pay off over a reasonable period (in terms of heating savings – of course this also depends on the heating technology).
Could you help me clarify where I might be wrong? Why is sand-lime brick usually recommended for interior walls instead of aerated concrete? Soundproofing? Less crumbling when drilling? Price?
On the website of the well-known aerated concrete manufacturer, I read that they also achieve low U-values (below 0.2). But these blocks are then less stable, significantly more expensive, and worse in sound insulation... So can you really generalize about aerated concrete or do you need to specify the exact type of block? My supplier only talks about 36.5cm (14 inches) blocks. So I don’t really know which will actually be used... I should probably ask.
Is omitting additional insulation really the “state of the art” and reasonable (does it not pay off in heating costs) or just cheap?
As I said, I don’t want to build a passive house but an economically sensible concept.
Which wall structure would you recommend and why under the above conditions?
Thank you!
H
Hausqualle22 Jul 2015 20:13Schrimp schrieb:
I lack the understanding/practical experience for this.. Actually, you should spend a few hours discussing this with a building physicist... because the whole topic is so extensive that I could write books about it...
Bautraum201522 Jul 2015 20:41I am particularly interested in your point about poor thermal insulation in the summer. Is that really the case? I have read the opposite online, but I also have no expertise in this.
Aerated concrete can be installed without additional insulation. But is that really effective? Is it just enough to meet legal requirements, or does it make sense to build this way?
Of course, you can also build monolithically with Poroton. With 48 cm (19 inches) Poroton, you exceed all requirements – with 36.5 cm (14 inches) you meet them.
Aerated concrete has poorer sound insulation compared to sand-lime brick or Poroton. This could be problematic, especially for thin interior walls.
Yes and no – Poroton doesn’t have a much better sound insulation value than aerated concrete. Sand-lime brick does, to a certain extent. Some building companies therefore build interior walls with sand-lime brick. (The heavier the material, the better the sound insulation – it’s best to check the datasheets.)
No matter what I build (even without an extra insulation layer), a controlled mechanical ventilation system is highly recommended since the houses are all very airtight.
It is definitely a gain in comfort. Over the last three years, I have lived in two rental apartments that were already more or less “airtight” (although from 1997 and renovated), and every time I entered them, I was met with a blast of stale air.
Aerated concrete has poor thermal insulation properties in summer (which I still don’t understand – how can a wall supposedly insulate well in one direction, winter, but not in the other, summer?).
This goes back to the mass effect – the heavier the material, the more thermal inertia it provides (the more heat or even “cold” a wall can store). Sand-lime brick takes longer to warm up. Another aspect is the time lag, basically the delay before heat enters the building. For example, if this delay is 14 hours, the midday heat arrives indoors at night. Think of a church in midsummer – a similar idea. Without shading and during prolonged heat waves, though, this also has its limits.
I’ve often read that the costs of applying additional insulation to a wall don’t pay off financially within a reasonable time (in terms of heating cost savings – of course, this also depends on the heating technology).
I think it depends on your perspective… Whether it’s 14 cm (5.5 inches) or 16 cm (6.3 inches) of insulation wool from the hardware store doesn’t make a huge difference – but if the supplier wants to find your price point and escalates costs significantly in 2 cm (0.8 inch) steps with hefty markups, that definitely adds up. If you’re considering adding an external thermal insulation composite system (ETICS) onto your Poroton, it generally tends not to be worthwhile.
Of course, you can also build monolithically with Poroton. With 48 cm (19 inches) Poroton, you exceed all requirements – with 36.5 cm (14 inches) you meet them.
Aerated concrete has poorer sound insulation compared to sand-lime brick or Poroton. This could be problematic, especially for thin interior walls.
Yes and no – Poroton doesn’t have a much better sound insulation value than aerated concrete. Sand-lime brick does, to a certain extent. Some building companies therefore build interior walls with sand-lime brick. (The heavier the material, the better the sound insulation – it’s best to check the datasheets.)
No matter what I build (even without an extra insulation layer), a controlled mechanical ventilation system is highly recommended since the houses are all very airtight.
It is definitely a gain in comfort. Over the last three years, I have lived in two rental apartments that were already more or less “airtight” (although from 1997 and renovated), and every time I entered them, I was met with a blast of stale air.
Aerated concrete has poor thermal insulation properties in summer (which I still don’t understand – how can a wall supposedly insulate well in one direction, winter, but not in the other, summer?).
This goes back to the mass effect – the heavier the material, the more thermal inertia it provides (the more heat or even “cold” a wall can store). Sand-lime brick takes longer to warm up. Another aspect is the time lag, basically the delay before heat enters the building. For example, if this delay is 14 hours, the midday heat arrives indoors at night. Think of a church in midsummer – a similar idea. Without shading and during prolonged heat waves, though, this also has its limits.
I’ve often read that the costs of applying additional insulation to a wall don’t pay off financially within a reasonable time (in terms of heating cost savings – of course, this also depends on the heating technology).
I think it depends on your perspective… Whether it’s 14 cm (5.5 inches) or 16 cm (6.3 inches) of insulation wool from the hardware store doesn’t make a huge difference – but if the supplier wants to find your price point and escalates costs significantly in 2 cm (0.8 inch) steps with hefty markups, that definitely adds up. If you’re considering adding an external thermal insulation composite system (ETICS) onto your Poroton, it generally tends not to be worthwhile.
H
Hausqualle22 Jul 2015 20:56Bautraum2015 schrieb:
I am especially interested in your point about poor thermal insulation in summer. Is that really the case? .. Complete nonsense to the power of 10 ... whether winter or summer, it doesn’t matter, the building material’s physical properties do not change.Bautraum201522 Jul 2015 20:58I think so too... that's why I'm asking.
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