ᐅ What can a blower door test reveal? Which house performance values are measured?
Created on: 16 Feb 2012 09:30
K
kako78Hello everyone!
We have built a prefabricated house and are moving in this week. A few weeks ago, we noticed that the right side of the attic was damp. We reported this to the prefab company, and were told that “the issue had been fixed.” Afterwards, the blower door test was conducted. We received a report (n50=1.0) and confirmation that the test was successful. However, we later found out that the problem in the attic had not been resolved (only the wet insulation wool was replaced, but the cause was not fixed), and now we already have mold on the wooden beams.
My question is: shouldn’t this have been detected during the blower door test? Were we just shown a blower door test as a formality, or is it true that openings in the vapor barrier cannot be detected with this test? I had thought that this was exactly what a blower door test is for???
Thank you very much for any information regarding this topic!
Katrin
We have built a prefabricated house and are moving in this week. A few weeks ago, we noticed that the right side of the attic was damp. We reported this to the prefab company, and were told that “the issue had been fixed.” Afterwards, the blower door test was conducted. We received a report (n50=1.0) and confirmation that the test was successful. However, we later found out that the problem in the attic had not been resolved (only the wet insulation wool was replaced, but the cause was not fixed), and now we already have mold on the wooden beams.
My question is: shouldn’t this have been detected during the blower door test? Were we just shown a blower door test as a formality, or is it true that openings in the vapor barrier cannot be detected with this test? I had thought that this was exactly what a blower door test is for???
Thank you very much for any information regarding this topic!
Katrin
B
Bauexperte16 Feb 2012 23:22Hello Katrin,
The adjustable fan first creates negative pressure inside the building. At a constant pressure difference between inside and outside, the volume of air moved by the fan is measured. This airflow rate is then related to the heated building volume to calculate the air change rate. The same procedure is applied using positive pressure, and the two calculated air change rates are averaged.
Kind regards
kako78 schrieb:A blower door is a testing device that helps assess the airtightness of buildings. During this airtightness test, a wind load is simulated to determine how well the building envelope resists natural wind pressure. The required pressure difference between the inside and outside is created by a controllable fan installed in a door or window opening.
I actually thought a BDT was specifically for this purpose???
The adjustable fan first creates negative pressure inside the building. At a constant pressure difference between inside and outside, the volume of air moved by the fan is measured. This airflow rate is then related to the heated building volume to calculate the air change rate. The same procedure is applied using positive pressure, and the two calculated air change rates are averaged.
Kind regards
H
Häuslebauer4023 Feb 2012 19:22The blower door test tells you that you know that you don’t know anything.
We also had a blower door test done. The result was quite decent, 1.43.
The friendly technician also showed me exactly where the leaks were. All minor issues (for example, a shutter strap outlet), which couldn’t really be the cause of major moisture problems in the house.
We also have an insulated but unfinished attic, which looked more like a dripstone cave.
Because of that and an intuitive feeling, I opened the vapor barrier last weekend and checked inside. The insulation was completely soaked. Everywhere.
In the meantime, there is mold growth on some walls, moisture rising from the floor in the utility room along the exterior wall, and so on.
So as you can see, a good blower door test result actually does not say anything about the quality of construction.
We also had a blower door test done. The result was quite decent, 1.43.
The friendly technician also showed me exactly where the leaks were. All minor issues (for example, a shutter strap outlet), which couldn’t really be the cause of major moisture problems in the house.
We also have an insulated but unfinished attic, which looked more like a dripstone cave.
Because of that and an intuitive feeling, I opened the vapor barrier last weekend and checked inside. The insulation was completely soaked. Everywhere.
In the meantime, there is mold growth on some walls, moisture rising from the floor in the utility room along the exterior wall, and so on.
So as you can see, a good blower door test result actually does not say anything about the quality of construction.
B
Bauexperte24 Feb 2012 11:11Hello,
That is partly true because it only provides a snapshot in time; on the other hand, it reveals leaks and thus helps prevent heating costs from spiraling out of control.
The build quality should be monitored by the site manager during construction or – which I often recommend here – if there is uncertainty about the expected quality, it should be outsourced to an external trusted institution or professional.
Best regards
Häuslebauer40 schrieb:
As you can see, a good blower door test result actually does not say much about the build quality.
That is partly true because it only provides a snapshot in time; on the other hand, it reveals leaks and thus helps prevent heating costs from spiraling out of control.
The build quality should be monitored by the site manager during construction or – which I often recommend here – if there is uncertainty about the expected quality, it should be outsourced to an external trusted institution or professional.
Best regards
Häuslebauer40 schrieb:
We also have an insulated but unfinished attic, which felt more like a dripstone cave. Hello!
Isn’t there a basic principle: either insulated and heated, or uninsulated and (of course) unheated!?
Otherwise: see above.
Best regards,
TomTom1.
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