ᐅ Insulating a New Build with 36.5 cm Aerated Concrete Blocks?
Created on: 17 Jan 2014 14:00
B
bygoran
Hello
our new build starts on Monday.
I am considering insulating the 36.5cm (14.4 inches) aerated concrete wall right away while the scaffolding is still in place.
We are building without KfW funding but want to insulate as well as possible.
According to a U-value calculator, I need 200mm (8 inches) of insulation to avoid moisture problems. Is that correct?
Can someone provide more detailed information? Or calculate exactly how thick the insulation needs to be to avoid any issues.
A controlled mechanical ventilation system with heat recovery is also planned.
The last ceiling below the cold roof is made of 24cm (9.5 inches) concrete, and I plan to add 240mm (9.4 inches) mineral wool insulation with a thermal conductivity of 0.035 W/(m·K). Is that sufficient?
I would appreciate any information.
our new build starts on Monday.
I am considering insulating the 36.5cm (14.4 inches) aerated concrete wall right away while the scaffolding is still in place.
We are building without KfW funding but want to insulate as well as possible.
According to a U-value calculator, I need 200mm (8 inches) of insulation to avoid moisture problems. Is that correct?
Can someone provide more detailed information? Or calculate exactly how thick the insulation needs to be to avoid any issues.
A controlled mechanical ventilation system with heat recovery is also planned.
The last ceiling below the cold roof is made of 24cm (9.5 inches) concrete, and I plan to add 240mm (9.4 inches) mineral wool insulation with a thermal conductivity of 0.035 W/(m·K). Is that sufficient?
I would appreciate any information.
Arguments. This is about facade renovation... of course, the facades are renovated, but not the external thermal insulation composite system (ETICS) itself (which was not touched...). Every plaster facade needs regular maintenance, but not the insulation behind it or the masonry (both last longer if properly installed, and both fail if done poorly). And the mentioned 22 years is actually a very long time for a plaster facade....
According to the study, damage was even found more frequently on facades with a monolithic wall construction -> so you have a higher likelihood of needing renovations here! According to this study, an ETICS actually presents a lower risk of future expenses.
Alright, I’m out—I'll do as the people in the green forum do. You can’t have a discussion with you; you twist and turn things and either can’t or won’t understand.
According to the study, damage was even found more frequently on facades with a monolithic wall construction -> so you have a higher likelihood of needing renovations here! According to this study, an ETICS actually presents a lower risk of future expenses.
Alright, I’m out—I'll do as the people in the green forum do. You can’t have a discussion with you; you twist and turn things and either can’t or won’t understand.
In the publication I read, a damage-free period of 22 years is assumed for ETICS (External Thermal Insulation Composite Systems) and 35 years for mineral-based exterior plaster. The silicone resin plaster used today on monolithic facades certainly has a significantly longer service life.
ETICS facades were regularly maintained to achieve these lifespans. Also, their thicknesses were not comparable to those of today’s ETICS systems. Likewise, the 2mm (0.08 inch) plaster layer certainly hasn’t always been that thin.
But putting studies aside for a moment, just think logically. Walk through any city and you’ll see hundreds of cases of ETICS renovation. And you’ll also see buildings 100 years old with their original plaster.
Think logically: The monolithic wall is mechanically much more robust and if damage occurs, it is easy to repair. There are no thermal bridges, no moisture problems, etc. If the wall thickness is reduced from 36.5cm (14.4 inches) to 33cm (13 inches) due to damage, it is simply patched up.
As you noted, monolithic walls have fewer problems with algae and fewer issues with woodpeckers.
Even if the ETICS facade is just 3% more prone to mechanical or moisture damage, it’s not worth paying 10 EUR per year more for a 25% improvement.
ETICS facades were regularly maintained to achieve these lifespans. Also, their thicknesses were not comparable to those of today’s ETICS systems. Likewise, the 2mm (0.08 inch) plaster layer certainly hasn’t always been that thin.
But putting studies aside for a moment, just think logically. Walk through any city and you’ll see hundreds of cases of ETICS renovation. And you’ll also see buildings 100 years old with their original plaster.
Think logically: The monolithic wall is mechanically much more robust and if damage occurs, it is easy to repair. There are no thermal bridges, no moisture problems, etc. If the wall thickness is reduced from 36.5cm (14.4 inches) to 33cm (13 inches) due to damage, it is simply patched up.
As you noted, monolithic walls have fewer problems with algae and fewer issues with woodpeckers.
Even if the ETICS facade is just 3% more prone to mechanical or moisture damage, it’s not worth paying 10 EUR per year more for a 25% improvement.
Jan, we are talking about a new build. Please, why would a builder cover a 17.5 cm (7 inch) Ytong block with polystyrene and then plaster it, when for the same or possibly less money they could plaster a 36 cm (14 inch) block without polystyrene? Shell versus solid composite. That’s the real question you face.
If higher costs are acceptable, then of course a 17.5 cm (7 inch) Ytong block plus insulation wool plus brick veneer is the best option. But for us, that’s too expensive. And it won’t actually be any warmer inside, just easier to maintain. And please don’t come with any lab values. If I can heat 100 sqm (1076 sq ft) for 600 per year and save just 10 by adding polystyrene, it doesn’t really matter.
If higher costs are acceptable, then of course a 17.5 cm (7 inch) Ytong block plus insulation wool plus brick veneer is the best option. But for us, that’s too expensive. And it won’t actually be any warmer inside, just easier to maintain. And please don’t come with any lab values. If I can heat 100 sqm (1076 sq ft) for 600 per year and save just 10 by adding polystyrene, it doesn’t really matter.
And what about the settlement cracks in the plaster that you often find on many monolithic walls? With external thermal insulation composite systems (ETICS), you have less trouble with that (although there are also reports that the panels can shrink and later cause cracks).
The savings are in the purchasing. But why repeat it, your calculation is solid. So what. It’s not about 10€ energy costs per year, completely insignificant (as you yourself also note – although for different reasons).
The savings are in the purchasing. But why repeat it, your calculation is solid. So what. It’s not about 10€ energy costs per year, completely insignificant (as you yourself also note – although for different reasons).
Our construction company would also apply a full-surface reinforcement mesh on the outside of the aerated concrete. I assume this should make settlement cracks at least as unlikely as with an external thermal insulation composite system (ETICS) / external wall insulation (EWI)?
I made my decision based on the advice of my brother, who is a master painter and has insulated thousands of rental buildings using the Sto system, and professionally considers it unsatisfactory. I simply trust him when he says that plastering is fine, but the building should be monolithic. The best option would be a brick veneer construction. However, we don’t have the budget for that, I’m close to retirement, and I want to be debt-free. The repayment period must not extend beyond 2023.
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