KfW55 with 36 cm brick (im)possible?

  • Erstellt am 2016-07-11 15:24:06

Redsonic

2016-07-14 23:30:09
  • #1
So we are currently also planning a KFW 55 house. It is to be built monolithically with 36.5 cm porous concrete (PPW2 is specified). In addition, there will be floor slab and ceiling insulation as well as an air heat pump. I also hope that everything will go through like this. However, the general contractor has had all thermal bridges certified at high cost (detailed proof) and therefore has less flat-rate deduction for the thermal bridge calculation. According to their statement, the KfW 55 is achievable, which I really hope for because our KfW loan depends on it.
 

DragonyxXL

2016-07-15 09:07:10
  • #2
No, the 42.5 alone would not have been enough. Maybe it would have worked with 42.5 at λ=0.07 and a detailed thermal bridge verification. However, you have to keep in mind that the 42.5 already costs 15% more, and 0.07 costs another 65% more than the 0.09. With our approximately 215 m² exterior wall, we're talking about significant additional costs. With the thermal bridge calculation, I would have estimated €8,000-12,000. The monolithic wall structure is not worth it to us.
 

daniels87

2016-07-15 11:11:51
  • #3
Crazy how different that can be. We pay about €1500 for the more extensive construction supervision and about €800 for the additional insulation. As mentioned, with 36.5 cm 0.09 bricks. Is it due to the worse surface/volume ratio of a bungalow?
 

DragonyxXL

2016-07-15 11:18:33
  • #4
That definitely makes a big difference, yes. However, our floor plan also complicates things. The highlight is, of course, the north/south orientation. We also only have southeast/northwest.
 

tabtab

2016-07-15 21:49:31
  • #5
I guess we would have also reached KFW55, but the loan was already finalized by then... so what?!
 

bvlgari

2016-07-17 09:26:04
  • #6
Are we talking about a "normal" T8/T9 or the variant with integrated insulation?
 

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