ᐅ Exterior Wall for KfW 40 (+) Standard: With or Without External Thermal Insulation Composite System (ETICS)?
Created on: 18 Feb 2021 11:23
F
Franke86
Hi everyone,
I need some advice. I’m currently planning my detached single-family house. The developer’s standard offering includes 24 hollow bricks plus 14 cm (5.5 inches) external wall insulation (EWI).
Since I want to build to KfW 40 (Plus) standard, they told me I would need 24 hollow bricks plus 18 cm (7 inches) EWI, which would cost an additional €1800.
What would you recommend? Is using EWI still considered "up-to-date," or is it becoming less common?
One advantage mentioned to me is that this creates a cavity wall construction, which offers better insulation and should also help prevent mold.
I also wanted to get some pricing for purely monolithic walls, and I received the following offer (standard is 24 hollow bricks + 14 cm (5.5 inches) EWI):
Which option would you choose, and are these additional costs typical or too high?
Brief details about the house: It’s a detached single-family home with a flat roof, approximately 160 sqm (1722 sq ft) living area, a ventilation system with heat recovery, and district heating for the heating.
Best regards,
Franke86
I need some advice. I’m currently planning my detached single-family house. The developer’s standard offering includes 24 hollow bricks plus 14 cm (5.5 inches) external wall insulation (EWI).
Since I want to build to KfW 40 (Plus) standard, they told me I would need 24 hollow bricks plus 18 cm (7 inches) EWI, which would cost an additional €1800.
What would you recommend? Is using EWI still considered "up-to-date," or is it becoming less common?
One advantage mentioned to me is that this creates a cavity wall construction, which offers better insulation and should also help prevent mold.
I also wanted to get some pricing for purely monolithic walls, and I received the following offer (standard is 24 hollow bricks + 14 cm (5.5 inches) EWI):
- T9 brick, thickness = 36.5 cm (14.4 inches) + €900
- 0.09 aerated concrete block, thickness = 36.5 cm (14.4 inches) + €900
- Hollow brick + 18 cm (7 inches) EWI = KfW 40+ compliant => + €1800
- T9 brick, thickness = 42.5 cm (16.7 inches) = ? KfW 40+ compliant => + €7000
- 0.09 aerated concrete block, thickness = 42.5 cm (16.7 inches) = ? KfW 40+ compliant => + €7000
Which option would you choose, and are these additional costs typical or too high?
Brief details about the house: It’s a detached single-family home with a flat roof, approximately 160 sqm (1722 sq ft) living area, a ventilation system with heat recovery, and district heating for the heating.
Best regards,
Franke86
Unfilled Poroton blocks are not only problematic for exterior walls. Sound travels remarkably well inside the house, transmitting to other floors. You experience strong structure-borne noise, which is why these blocks are prohibited in multi-story construction. Some people, like Zaba, might not be affected, but from a technical standpoint, using such blocks is not a good idea. Unfortunately, I was persuaded by the builder to use them. By now, I know many who would never build with these blocks again.
Hollow-filled blocks provide peace and quiet.
Hollow-filled blocks provide peace and quiet.
I installed mineral wool on the facade.
The painting company responsible for the job always said that the "plastic" alternatives are suspected of releasing carcinogenic emissions. After 15 years, there is a risk that the material shrinks and the facade becomes unsightly. It’s hard to tell whether this is true or just common gossip.
As for the facts: The plastic material is combustible (yes, “fire-resistant” still means combustible). For this reason, fire barriers made of mineral wool must be installed under certain conditions. I don’t want a combustible facade.
Another fact is that disposing of the plastic material is extremely expensive. Because of all the chemical components, it must be burned as hazardous waste. Would you want something like that on your facade if it really emits harmful substances?
The painting company responsible for the job always said that the "plastic" alternatives are suspected of releasing carcinogenic emissions. After 15 years, there is a risk that the material shrinks and the facade becomes unsightly. It’s hard to tell whether this is true or just common gossip.
As for the facts: The plastic material is combustible (yes, “fire-resistant” still means combustible). For this reason, fire barriers made of mineral wool must be installed under certain conditions. I don’t want a combustible facade.
Another fact is that disposing of the plastic material is extremely expensive. Because of all the chemical components, it must be burned as hazardous waste. Would you want something like that on your facade if it really emits harmful substances?
Tassimat schrieb:
I have mineral wool insulation on the facade.
The painting company that was allowed to do the work always said that the "plastic" types are suspected of releasing carcinogenic emissions. After 15 years, there is a risk that the material shrinks and the facade becomes unsightly. Whether this is true or just hearsay is always hard to tell.
As for the facts: The plastic-based materials are combustible (yes, flame-retardant still means combustible). That’s why, under certain conditions, fire barriers made of mineral wool have to be installed. I do not want a combustible facade.
It is also a fact that disposing of the plastic-based materials is extremely expensive. Because of all the components, they have to be disposed of as hazardous waste by incineration. Would anyone want that on their facade if it actually emits gases? But that’s partly just urban myth. If there were any emissions, then who cares? I’d be more worried about what’s inside the house—and guess what is installed under the screed...
Of course, there is a bit of storytelling involved.
It’s just like the whole topic of organic or Demeter products in the supermarket. Is organic better? Definitely. But will you get sick from the cheap ground meat bought for ridiculously low prices? Certainly not.
Everyone has to decide for themselves where they want to spend money for their own peace of mind. I just decided to indulge a bit with the facade 😎
It’s just like the whole topic of organic or Demeter products in the supermarket. Is organic better? Definitely. But will you get sick from the cheap ground meat bought for ridiculously low prices? Certainly not.
Everyone has to decide for themselves where they want to spend money for their own peace of mind. I just decided to indulge a bit with the facade 😎
Tassimat schrieb:
Definitely. But will you get sick right away from the cheap stuff that costs ridiculously little? Certainly not.
Everyone has to decide for themselves where they supposedly invest in something good for their peace of mind. I treated myself to something nice for the facade 😎See... now I’m treating myself to organic meat at the counter 😉
Hello,
That’s an old myth and repeating it doesn’t make it true…. For several years now, no HBCD has been added, so this is no longer classified as hazardous waste and can be processed normally by thermal recovery. In fact, most of the previously carefully separated yellow bags are treated the same way. They are all incinerated together with regular household waste…
If you don’t like polystyrene on the wall (and I admit, it just sounds awful when you knock on it), I would recommend taking a look at mineral wool. It is definitely non-combustible and also improves sound and heat insulation somewhat.
Unfilled T7-10 Poroton bricks are strongly discouraged. The sound insulation is arguably not much better than that of a tent…
My recommendation: forget the KfW 40+ nonsense and build the house with a solid, möglichst heavy masonry unit. Either sand-lime brick or Poroton perforated clay brick. Then apply ETICS (external thermal insulation composite system) on the outside, and that’s it.
Best regards,
Andreas
Tassimat schrieb:
The fact is that disposal of that plastic stuff is insanely expensive. Due to all the ingredients, it has to be burned as hazardous waste.
That’s an old myth and repeating it doesn’t make it true…. For several years now, no HBCD has been added, so this is no longer classified as hazardous waste and can be processed normally by thermal recovery. In fact, most of the previously carefully separated yellow bags are treated the same way. They are all incinerated together with regular household waste…
If you don’t like polystyrene on the wall (and I admit, it just sounds awful when you knock on it), I would recommend taking a look at mineral wool. It is definitely non-combustible and also improves sound and heat insulation somewhat.
Unfilled T7-10 Poroton bricks are strongly discouraged. The sound insulation is arguably not much better than that of a tent…
My recommendation: forget the KfW 40+ nonsense and build the house with a solid, möglichst heavy masonry unit. Either sand-lime brick or Poroton perforated clay brick. Then apply ETICS (external thermal insulation composite system) on the outside, and that’s it.
Best regards,
Andreas
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