ᐅ Blower Door Test – Meaning of the Result

Created on: 5 Jan 2018 23:51
A
AndreasPlü
Hello,

Today, as the final trade in our already occupied house, we had the airtightness test.

The result: N 50 = 0.68

We built a solid KfW 70 (2017) standard house. What does this mean? Is this good, acceptable, or rather mediocre?

Should we expect particularly harmful leaks? The tester detected a slight leakage at a sliding door but considered it within acceptable limits, which brings us back to the original question.
F
FundS
28 Dec 2018 18:53
When is the Bloßer door test usually performed?
blackm8828 Dec 2018 21:27
It varies greatly depending on the builder. In our case, the blower door test was done after the shell was complete, with the exterior still not plastered and the interior walls not yet finished. Of course, the windows were already installed. The site manager then said that based on the results, he knew his team had done an excellent job. Construction continued afterward.
However, there are cases where the blower door tester comes multiple times until the desired value is reached, because the house has too much leakage. This can be frustrating if the exterior plaster and interior walls are already finished...
D
denz.
28 Dec 2018 22:58
Does everyone actually do this blower door test? Or only if it is required by KFW or someone else?

We are building quite “normally” and I wonder if I should spend around €500 for it.
Obviously, the results can only be poor if there are serious drafts, and I would notice that even without the test.
H
haydee
29 Dec 2018 05:23
What is normal?
If you have a mechanical ventilation system with heat recovery, I would recommend installing one.
With an air change rate of 1.5 or lower, there is no noticeable draft.
For many companies, values around 1.0 indicate that something is wrong.
L
Leckagefuchs
30 Dec 2018 13:34
Hello everyone

A few answers to the questions
When to measure? It is clear that the B measurement is better for the building and its future use:
Structural shell completed, interior plaster finished, vapor barriers installed but without coverings
Various main doors may still be missing.
In this condition, leaks can still be repaired inexpensively.
The cost of a measurement of about 250€ (approximately $270) is negligible compared to discovering problems in the finished house such as “something is wrong.”
Increased heating costs, mold growth, drafts
Consider the measurement as a quality control step for the site management.
R
Reini1234
7 Feb 2020 08:29
I’d like to bring this thread up again.

We have now received our result: 1.36. The measurement was taken shortly before moving in. We have a ventilation system, but it is not yet operational, and the wall openings for fresh and exhaust air have not been made. The exterior plaster on the basement is completely missing.

Should we be concerned? How does this relate to the better required value of 1.5 with a ventilation system?