Blower-Door Test (individual contract component with n50 value)

  • Erstellt am 2020-05-03 14:49:59

rainario1

2020-05-03 14:49:59
  • #1
Hello everyone,

so far I have mostly just read "passively" and I was banned immediately after my first post (rightly so, because of posting links), so now I will briefly introduce myself: I am 40 years old and want to build a prefabricated house with my bride. Strictly speaking, two semi-detached houses. More strictly speaking, "have it built" (my father would say).

We are now about to sign the contract for work, but the representative of our "presumably chosen" prefabricated house supplier does not want to include the individual contractual clause on the BDT n50 value < 1.0 1/h in the contract without further ado.

He insists on 1.5 1/h, although I was even able to speak by phone with the head of building physics on the subject, who said: "On average, we achieve values around 0.9 ... so better than 1.0 ... we can do that." Even 0.9, as far as I know, is not a masterpiece. The supplier is one of the largest prefabricated house manufacturers in Germany.

Justification from the representative:
"Since the basement is provided by the builder (separate contract), it cannot be ensured that there might not be leaks due to openings and penetrations during the measurement. It would have to be contractually agreed that these are to be sealed (covered, sealed) by the builder."

My goal: I would like to ensure that there are no unnecessary leaks that are then dismissed as "insignificant" by the general contractor because the KfW guideline (n50 value below 1.5 1/h) was achieved.

We all know that the KfW recommends a value <0.6. Strictly speaking, I should contractually demand a value better than 0.6 1/h – however, that seems unrealistic to me, they probably won’t agree to that.

How else can I get the general contractor to meet the BDT with a "top result"? The easiest solution would certainly be to accept the aforementioned demand, i.e. it would have to be contractually agreed that the interface to the basement is to be sealed (covered, taped) by the builder.

The BDT takes place in the shell construction state, as can be read in other posts, this makes sense. Can I manage/ensure the sealing in the shell construction state? The crucial point: is the door to the basement usually installed at this stage?

Bold additional question: I find the price of the BDT too high, 850 euros per semi-detached house are being charged here, do you see "room for negotiation"? I will also ask this question to the supplier... I just want to have your esteemed opinion beforehand.

Thanks in advance!
 

seat88

2020-05-03 17:17:02
  • #2
Controlled residential ventilation?
Window rebate ventilation?
Passive house? How do you build?
 

rainario1

2020-05-03 19:28:49
  • #3
Standard Kfw 40 with air-water heat pump LWZ 5 from Stiebel Eltron, which has a ventilation function.
 

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