ᐅ Materials for Exterior and Interior Walls (KfW 55 Standard)
Created on: 13 Aug 2021 14:16
B
Baumeister86
Dear all,
After initial discussions with local general contractors and reviewing construction specifications, some questions arose regarding the wall materials (assembly).
We would like to build to the KfW 55 standard, as it doesn’t seem to deviate much from the usual practice. Additionally, we want good sound insulation (unfortunately, the air traffic from BER airport can still be heard in eastern Berlin, even though planes will not fly directly over us). Therefore, I am a bit overwhelmed by the many exterior wall options.
Monolithic construction seems advantageous to me, as masonry should last much longer than external thermal insulation composite systems (ETICS) and require less maintenance. Are there any reliable experiences with ETICS? Also, I’m a bit unsure about calcium silicate brick (best sound insulation, but I don’t want sand falling down every time I drill). How is the maintenance of facade render handled? I cannot recall my parents having that done in almost 30 years (house built in the late 1970s).
Porous concrete with a wall thickness of 36.5 cm (14 inches) should meet KfW requirements (U-value <0.2), while clay blocks require additional filling with perlite. However, from what I have researched, sound insulation of clay blocks is better than porous concrete, at least on paper. How does this compare in practice?
Lightweight expanded clay aggregate blocks were also offered to us (however, as a pre-assembled system wall). You would need a lot of ETICS on this to meet the KfW standard—how is the sound insulation in this case?
Most importantly, what are the costs of these options (calcium silicate brick + ETICS vs. porous concrete vs. insulated clay blocks) for, say, a city villa with a 10 x 10 m (33 x 33 ft) footprint? Most general contractors work only with one option or the other (and I have not yet found any insulated clay blocks).
To avoid noise transmission inside the house, regular clay block walls seem reasonable (12 cm or 24 cm [5 or 10 inches] if load-bearing). Calcium silicate bricks seem somewhat heavy (and the sand issue)?
Thank you very much for your opinions.
Stephan
P.S.: Are we really looking at 2100–2500 €/m² (195–230 $/ft²) for a “normal standard” house now in Brandenburg? Or did we consult the wrong general contractors?
After initial discussions with local general contractors and reviewing construction specifications, some questions arose regarding the wall materials (assembly).
We would like to build to the KfW 55 standard, as it doesn’t seem to deviate much from the usual practice. Additionally, we want good sound insulation (unfortunately, the air traffic from BER airport can still be heard in eastern Berlin, even though planes will not fly directly over us). Therefore, I am a bit overwhelmed by the many exterior wall options.
Monolithic construction seems advantageous to me, as masonry should last much longer than external thermal insulation composite systems (ETICS) and require less maintenance. Are there any reliable experiences with ETICS? Also, I’m a bit unsure about calcium silicate brick (best sound insulation, but I don’t want sand falling down every time I drill). How is the maintenance of facade render handled? I cannot recall my parents having that done in almost 30 years (house built in the late 1970s).
Porous concrete with a wall thickness of 36.5 cm (14 inches) should meet KfW requirements (U-value <0.2), while clay blocks require additional filling with perlite. However, from what I have researched, sound insulation of clay blocks is better than porous concrete, at least on paper. How does this compare in practice?
Lightweight expanded clay aggregate blocks were also offered to us (however, as a pre-assembled system wall). You would need a lot of ETICS on this to meet the KfW standard—how is the sound insulation in this case?
Most importantly, what are the costs of these options (calcium silicate brick + ETICS vs. porous concrete vs. insulated clay blocks) for, say, a city villa with a 10 x 10 m (33 x 33 ft) footprint? Most general contractors work only with one option or the other (and I have not yet found any insulated clay blocks).
To avoid noise transmission inside the house, regular clay block walls seem reasonable (12 cm or 24 cm [5 or 10 inches] if load-bearing). Calcium silicate bricks seem somewhat heavy (and the sand issue)?
Thank you very much for your opinions.
Stephan
P.S.: Are we really looking at 2100–2500 €/m² (195–230 $/ft²) for a “normal standard” house now in Brandenburg? Or did we consult the wrong general contractors?
Baumeister86 schrieb:
It says the building material is Liaplan (which is expanded clay)Oh, you’re right 🙄, living inside has been good for 2 years now
E
erazorlll13 Aug 2021 21:33Baumeister86 schrieb:
From a wall thickness of 36.5cm (14 inches), aerated concrete should meet the requirements of the KfW standard (U-value <0.2), while Poroton needs additional filling with perlite.
However, the sound insulation of Poroton is better than that of aerated concrete, if my research is correct (at least on paper). How does this perform in practice? I asked myself the same question for our supplier selection, compared materials and blocks, and asked here in the forum because soundproofing was important to us.
Take a look at the sound insulation values of aerated concrete (somewhere in the upper 40 dB range) and windows (usually around the mid to upper 30 dB range), then you’ll see where the issue lies. And if you plan with a lot of window area, I wouldn’t worry too much about the blocks.
We faced the same choice.
Insight 1
In Berlin and its surroundings, buildings are mainly constructed with white blocks. Mostly Ytong, less often calcium silicate blocks.
I come from the Harz region, where almost exclusively red blocks (Poroton) are used, which I think is very regional.
In my opinion, Ytong is easier for the shell builder to work with, is a mass-produced product, and allows for faster construction. (This “good” residual moisture after moving in).
We were more or less persuaded by the architect to choose calcium silicate blocks with external thermal insulation composite systems (ETICS / WDVS), even though we don’t expect much noise in the countryside (near Tesla).
We had price offers for both Ytong and calcium silicate blocks with ETICS, and Ytong was about 10–15% cheaper for the shell construction.
Conclusion: We are going with calcium silicate blocks 🙂
Insight 1
In Berlin and its surroundings, buildings are mainly constructed with white blocks. Mostly Ytong, less often calcium silicate blocks.
I come from the Harz region, where almost exclusively red blocks (Poroton) are used, which I think is very regional.
In my opinion, Ytong is easier for the shell builder to work with, is a mass-produced product, and allows for faster construction. (This “good” residual moisture after moving in).
We were more or less persuaded by the architect to choose calcium silicate blocks with external thermal insulation composite systems (ETICS / WDVS), even though we don’t expect much noise in the countryside (near Tesla).
We had price offers for both Ytong and calcium silicate blocks with ETICS, and Ytong was about 10–15% cheaper for the shell construction.
Conclusion: We are going with calcium silicate blocks 🙂
Stephan— schrieb:
We faced the same choice.
Insight 1
In Berlin and nearby areas, construction mainly uses white blocks. Mostly Ytong, less often sand-lime bricks.
I come from the Harz region, where almost exclusively red bricks (Poroton) are used, so I think it's very regional.
In my opinion, Ytong is easier for the shell builder to work with, it’s a mass-produced product, and it allows for fast construction. (This “good” residual moisture after moving in).
We more or less let the architect persuade us towards sand-lime bricks and external thermal insulation composite systems (ETICS), even though we don’t expect much noise out in the sticks (near Tesla).
We had price quotes for both Ytong and sand-lime bricks with ETICS, and Ytong was about 10–15% cheaper for the shell construction.
Conclusion: We are going with sand-lime bricks 🙂 Were you ever presented with clay bricks and breathable walls? By the way, I’m also from the Harz region, more precisely from the heart of the Harz (lived in Goslar for 13 years) :-)
We will be building with Poroton clay bricks in Brandenburg. 36.5 cm (14.4 inches) bricks without ETICS, but still meeting KFW 55 standard.
Good evening,
I have the same question as the original poster. Thanks @Baumeister86, perfect timing to ask this here!
So, is the conclusion basically a matter of preference between filled Poroton or sand-lime brick plus external thermal insulation composite system (ETICS)?
Both meet the KFW55 standard and both insulate so well that, in the end, the windows are the weakest link in the chain.
1. Are the costs roughly comparable?
2. How about durability, in terms of “leaving something behind for the grandchildren” (if there ever will be any)?
3. Bonus question: What thickness should the interior walls of sand-lime brick be at minimum to provide good sound insulation between rooms?
I imagine it’s very difficult to test this during a show home visit and am hoping for real-world experience here, even if subjective.
Sorry for jumping in here like this. If this breaks any forum etiquette, please just let me know briefly.
Good luck
I have the same question as the original poster. Thanks @Baumeister86, perfect timing to ask this here!
So, is the conclusion basically a matter of preference between filled Poroton or sand-lime brick plus external thermal insulation composite system (ETICS)?
Both meet the KFW55 standard and both insulate so well that, in the end, the windows are the weakest link in the chain.
1. Are the costs roughly comparable?
2. How about durability, in terms of “leaving something behind for the grandchildren” (if there ever will be any)?
3. Bonus question: What thickness should the interior walls of sand-lime brick be at minimum to provide good sound insulation between rooms?
I imagine it’s very difficult to test this during a show home visit and am hoping for real-world experience here, even if subjective.
Sorry for jumping in here like this. If this breaks any forum etiquette, please just let me know briefly.
Good luck
M
motorradsilke13 Aug 2021 23:10Baumeister86 schrieb:
P.S.: Are we really at 2100-2500 €/sqm for a "standard" house nowadays in Brandenburg? Or did we deal with the wrong general contractors?We are currently building in Brandenburg as well, and that seems about right. After finalizing selections and the first moderate price increase, we expect to reach around 2200 €/sqm, excluding additional construction costs and landscaping, but including KfW55 standards.
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