ᐅ Blower Door Test – At Which Stage of Construction Should It Be Performed?

Hello everyone,

We are finally about to start building soon, and today I received the preliminary schedule for the various trades from the general contractor.

What confused me was that the blower door test is scheduled at the very end, about one calendar week before the planned handover. I had thought that the test is usually done once the building is sealed—or should be—meaning when all windows and doors are installed and the roof is completed. That way, it would be much easier to carry out any necessary repairs if the test reveals any air leaks.

Are there any regulations or standards, such as DIN, that specify the timing for this test?

Thank you in advance!

I’m not an expert, but to my knowledge, both plasters (interior and exterior) also have a sealing function. They are applied almost at the very end, so that fits, depending on whether painting and flooring work are included or not.

We had two measurements. The first was after I insulated the upper floor ceiling and installed the vapor retarder. It made sense to test everything before installing the drywall. The second was shortly after moving in.

If insulation and drywall are removed, I think it makes the most sense to carry out the measurement after applying the exterior render (stucco).

We had two tests. One as soon as the building envelope was sealed—before the screed, plaster, etc. This was simply because, with the Passive House standard, we need to achieve a very low value. Mistakes can only be properly corrected at that stage. The second test was done around the handover date for the KfW funding.

The person who conducted the test said that usually the test is only done for KfW purposes. Many general contractors consistently achieve values well below the required limits.

We only had one blower door test. It was conducted after the interior plaster was applied and before the drywall sheets were installed on the upper floor, so the roofing membrane could still be inspected.