ᐅ Exterior Wall for KfW 40 (+) Standard: With or Without External Thermal Insulation Composite System (ETICS)?
Created on: 18 Feb 2021 11:23
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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
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nordanney18 Feb 2021 14:07Franke86 schrieb:
Is this good or bad now XDNeither. It’s just a different wall construction.P
pagoni202018 Feb 2021 14:49@Franke86 Since you want to build to KfW standards, you will need an energy consultant anyway. Only they can give you the exact requirements; everything else is mostly guesswork.
I would probably also recommend going for the “better” brick, and the additional cost I’ve read about so far sounds reasonable.
Of course, the building envelope is a key factor in this calculation, but so are thermal bridges, windows, roof, etc.
The best envelope doesn’t help if other components are average, or if the insulation reaches a certain thickness where it no longer has much impact relative to the effort.
If you “save” on the brick, you’ll end up paying elsewhere to meet your target values. The energy consultant handles this “balancing” once they have assessed your house.
Then you’ll quickly get your results and see the possible and sensible options.
You should also keep in mind that achieving this kind of standard often costs more than the subsidy covers. It is supposed to be a subsidy, not a full government payment (I’m not saying this about you personally!).
Sometimes I get the impression that the subsidy is just seen as a grant where you hope to save some money in the end. I believe it can cost more if necessary, since I also wanted a better-insulated house, KfW or not.
Isn’t there also the T8 brick? I had read something about that for our area at the beginning?
I would probably also recommend going for the “better” brick, and the additional cost I’ve read about so far sounds reasonable.
Of course, the building envelope is a key factor in this calculation, but so are thermal bridges, windows, roof, etc.
The best envelope doesn’t help if other components are average, or if the insulation reaches a certain thickness where it no longer has much impact relative to the effort.
If you “save” on the brick, you’ll end up paying elsewhere to meet your target values. The energy consultant handles this “balancing” once they have assessed your house.
Then you’ll quickly get your results and see the possible and sensible options.
You should also keep in mind that achieving this kind of standard often costs more than the subsidy covers. It is supposed to be a subsidy, not a full government payment (I’m not saying this about you personally!).
Sometimes I get the impression that the subsidy is just seen as a grant where you hope to save some money in the end. I believe it can cost more if necessary, since I also wanted a better-insulated house, KfW or not.
Isn’t there also the T8 brick? I had read something about that for our area at the beginning?
@Bookstar
? The filling is not the responsibility of the brick, but rather the structural engineering. Everything else is just a question of where the insulation is placed, although a combination of external thermal insulation composite system (ETICS) and insulation within the wall is often uneconomical and reduces the living space.
? The filling is not the responsibility of the brick, but rather the structural engineering. Everything else is just a question of where the insulation is placed, although a combination of external thermal insulation composite system (ETICS) and insulation within the wall is often uneconomical and reduces the living space.
Bookstar schrieb:
Definitely avoid hollow bricks! Even if I’m repeating myself... https://www.hausbau-forum.de/threads/aussenwandziegel-ungefuellt-gefuellt-oder-objektzieg-waehlen.28381/
Didn’t you have a different opinion here? 😉
Sure… that was back in 2018. May I ask why you’ve now become a supporter of filled bricks? Did you have negative experiences with the hollow ones?
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