ᐅ The previous owner made some modifications to the insulation. Do I need to take any action?

Hello,

first of all, I am a complete beginner and have little knowledge of DIY or construction topics. This is about a low-energy house built in 2012. The attic is insulated with mineral wool and a vapor barrier (or vapor retarder?).

Recently, the previous owner told me that birds once nested in the gable. On this long beam where the roof slopes rest. He said he had to re-insulate and seal everything from the inside at one spot (he is not a professional himself...).

When I wanted to check it at home, I found this upstairs (see photos).

The previous owner said he installed new foil, glued it back to the wall with matching adhesive, and sealed it additionally with tape. He put the insulation back behind it. Does this look okay, or should I have a professional check everything? By the way, I feel a very slight draft up there. A flame test with a lighter was normal. However, a hanging hair on the ceiling moved slightly. Shouldn’t it be completely airtight so that you don’t feel anything? I crawled all around but couldn’t find any damage to the foil...

Maybe someone has advice. Best regards

Rammler schrieb:

A single loose hair on the ceiling was slightly moving.

Oh dear, that does raise some concern 😉
Did you breathe? Did you move? 😉
No, seriously:

Rammler schrieb:

Shouldn't it be completely airtight?

This is the cold roof! And without plaster, nothing is airtight.

ypg schrieb:

Oh dear, that concern is certainly justified 😉
Did you breathe? Move? 😉
No, seriously:

This is a ventilated roof! And without plaster, nothing is airtight.

Ah, okay. I thought if the membrane is completely under the roof, it has to be 100% airtight. Thanks for your input.

The question here is why there is still a membrane installed on top. Since the building was constructed in 2012, the seller should still have all the documentation. Therefore, I would check what is supposed to be behind the membrane and whether it is important for thermal insulation. Also, inspect the ventilation of the attic. A cold roof should be ventilated, in which case the insulation of the roof slopes and the vapor retarder can actually be omitted.

Well, that looks like a ventilation duct (rectangular duct), doesn’t it? It must be inside the thermal envelope, which might be why the roof was insulated afterward. No idea whether the ceiling insulation should actually have been removed in that case...