ᐅ Blower Door Test (included as part of the contract with n50 value)
Created on: 3 May 2020 14:49
R
rainario1R
rainario13 May 2020 14:49Hello everyone,
Since I have mostly been a passive reader for quite some time and my first post was immediately blocked (rightly so, due to posting links), I would like to briefly introduce myself now:
I am 40 years old and want to build a prefabricated house with my fiancée. More precisely, two semi-detached houses.
Strictly speaking, to have them "built for us" (as my father would say).
We are now just about to sign the construction contract, but the representative of our “presumably chosen” prefabricated house supplier does not want to include the individual contract clause regarding the blower door test (BDT) n50 value < 1.0 1/h in the contract without further discussion.
He insists on 1.5 1/h, even though I was able to speak with the head of building physics about this, who said: "On average, we achieve values around 0.9 … so better than 1.0 … we can manage that."
As far as I know, even 0.9 is not an exceptional achievement.
This supplier is one of the largest prefabricated house manufacturers in Germany.
The representative’s explanation:
"Since the basement is provided by the builder (separate contract), it cannot be guaranteed that there are no leakages due to openings and penetrations during the measurement. It would have to be contractually agreed that these must be sealed (covered, taped) by the homeowner."
My goal: I want to ensure that there are no unnecessary leaks that the general contractor (GC) might dismiss as “insignificant” simply because the KfW guideline (n50 value under 1.5 1/h) was met.
We all know that KfW recommends a value < 0.6.
Strictly speaking, I should demand a value better than 0.6 1/h in the contract – however, that seems unrealistic, as I doubt they would agree to that.
How else can I persuade the GC to achieve a “top result” in the blower door test?
The simplest solution would certainly be to accept the above-mentioned requirement, i.e., to contractually agree that the interface to the basement must be sealed (covered, taped) by the homeowner.
The blower door test takes place when the building shell is complete; as I have read in other posts, that makes sense.
Is it possible to provide or guarantee sealing at this stage?
Crucial point: is the door to the basement usually already installed by then?
A cheeky extra question:
I find the cost for the blower door test too high; 850 euros per semi-detached house are being charged. Do you see any “room for negotiation”?
I will ask the supplier this question as well... just wanted to get your valued opinion beforehand.
Thanks in advance!
Since I have mostly been a passive reader for quite some time and my first post was immediately blocked (rightly so, due to posting links), I would like to briefly introduce myself now:
I am 40 years old and want to build a prefabricated house with my fiancée. More precisely, two semi-detached houses.
Strictly speaking, to have them "built for us" (as my father would say).
We are now just about to sign the construction contract, but the representative of our “presumably chosen” prefabricated house supplier does not want to include the individual contract clause regarding the blower door test (BDT) n50 value < 1.0 1/h in the contract without further discussion.
He insists on 1.5 1/h, even though I was able to speak with the head of building physics about this, who said: "On average, we achieve values around 0.9 … so better than 1.0 … we can manage that."
As far as I know, even 0.9 is not an exceptional achievement.
This supplier is one of the largest prefabricated house manufacturers in Germany.
The representative’s explanation:
"Since the basement is provided by the builder (separate contract), it cannot be guaranteed that there are no leakages due to openings and penetrations during the measurement. It would have to be contractually agreed that these must be sealed (covered, taped) by the homeowner."
My goal: I want to ensure that there are no unnecessary leaks that the general contractor (GC) might dismiss as “insignificant” simply because the KfW guideline (n50 value under 1.5 1/h) was met.
We all know that KfW recommends a value < 0.6.
Strictly speaking, I should demand a value better than 0.6 1/h in the contract – however, that seems unrealistic, as I doubt they would agree to that.
How else can I persuade the GC to achieve a “top result” in the blower door test?
The simplest solution would certainly be to accept the above-mentioned requirement, i.e., to contractually agree that the interface to the basement must be sealed (covered, taped) by the homeowner.
The blower door test takes place when the building shell is complete; as I have read in other posts, that makes sense.
Is it possible to provide or guarantee sealing at this stage?
Crucial point: is the door to the basement usually already installed by then?
A cheeky extra question:
I find the cost for the blower door test too high; 850 euros per semi-detached house are being charged. Do you see any “room for negotiation”?
I will ask the supplier this question as well... just wanted to get your valued opinion beforehand.
Thanks in advance!
R
rainario13 May 2020 19:28Standard KfW 40 with an air-to-water heat pump LWZ 5 from Stiebel Eltron, which includes a ventilation function.
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