Vapor barrier roof - tape stapler nails?

Hello everyone,

we are currently having a Luxhaus (timber frame construction) built and had our shell inspection last week. An independent master carpenter pointed out to me that the staples used to attach the vapor retarder (I assume it is a vapor retarder and not a vapor barrier, since it is a PVC foil) at the transition to the attic should have been sealed with sealing tape for airtightness. (currently, they are not).

By the way: The attic of the truss roof is located outside the insulated area.

Luxhaus is quite relaxed about this and referred us to the blower door test. If there were any leaks, they would be detected during the blower door test. Sealing the staples would make them no longer competitive.

After some research on the blower door test, I came to the conclusion that it is not necessarily a conclusive confirmation that there are no leaks. On the one hand, because this test can be carried out by anyone without special qualifications, and on the other hand, meeting the KfW limits is no guarantee that there are no leaks due to construction defects.

How do you see it?

Best regards,
Anton

if the Blow-Door test is passed, leave it at that. The house then has the necessary airtightness. Absolutely airtight is not better but worse and requires controlled residential ventilation. If the staple clips are flush with the foil, that is good; if they sit too deep, meaning the foil is pierced through, that is bad and a construction defect.

Hello Nida35a,

thank you for your feedback.

Regards,
Anton

If the Blower-Door Test is passed, leave it at that. The house then has the necessary airtightness. Absolutely airtight is not better but worse and requires controlled residential ventilation.
If the staples are flush with the foil, that is good; if they are too deep, meaning the foil is pierced through, that is bad and a construction defect.

Unfortunately, that is wrong. A passed Blower Door Test does not say anything about leaks. It may be that a single leak destroys your roof even with a superb Blower Door Test result. But I do not see that in this case.

Unfortunately, that is incorrect. A passed blower door test does not say anything about leaks. It is possible that a single leak destroys your roof, even with a great blower door test result. But I do not see that in this case.

The BD test only indicates that the sum of all leaks is smaller than an allowable limit.
In this case, the membranes are not perforated like Swiss cheese.
This test was not conducted for our house at the owner's request.

If you have doubts and some time, it would be easy to do that yourself with a roll of Sicrall tape