House purchase - experiences with roof insulation?

Hello everyone,

I am in the middle of the project "house purchase." In other words, I am looking at properties and still searching for the right house at the right price. In this particular case, it is a house from the 90s. In the attic, there are two unfinished rooms. One of them looks like the one in the photo. From the other pictures, the house otherwise makes a good impression. I am only unsure about this one spot. I understand that this is just based on the photo and purely speculative, but could someone tell me if this is supposed to look like this or if maybe some shoddy work was done? What should I pay attention to during the viewing? Subjectively, the vapor barrier (?) is hanging down quite loosely there and also seems not to be sealed at the bottom. The listing says nothing about any retrofit insulation, so this appears to be the original condition from 30 years ago.



Best regards, Christian

The quality of the photo is rather not so good. It looks as if mineral wool was stuffed between the rafters and the foil was installed as a dust protection. That is (hopefully) not a vapor barrier.

Why does it look spotty? Is that wet? Mold? If it is wet, the question would be why and whether it can be fixed. Then definitely have a specialist take a look, possibly replacement is recommended. And possibly now empty a compartment and look at the outside. If it has been open all the time, moisture might have condensed on the outer layer.

Maybe a lot, little can be said from a distance.

In its new condition, the mineral wool between the rafters is yellow to white. Black means either wet and then moldy or simply dirty. Both can come in equally from inside and outside. In the present case, I would not fundamentally conclude damage to the roof. It can be quite easily clarified by looking/feeling/poking at the rafters at the lower edge. If the wood is good, it is uncritical. If it is rotten/crumbling/soft, stay away. Apart from that, the insulation should be redone with sealing. As it is now, it's rubbish anyway because air flows freely underneath. The effort is minimal though. Remove old wool, put in new wool, airtight seal the vapor barrier and then at least a lathing or drywall underneath, otherwise it will look like this again in a few years.

Thank you for the comments. I will take a look at it during the inspection and at the latest when your questions/comments are confirmed, I will have a professional take another look at it.

> As it is now, it’s nonsense anyway because air is freely flowing underneath.
Yes, that was my thought too. But I have no expertise in that area at all, although seals open to the bottom do look strange.

The dark area next to the window could also be interesting. Either a shadow or a damp spot. The roof does have an overhang, but if there is a thermal bridge there and it wasn’t properly heated, something could have formed there as well.

Result from the inspection...

The good news: the dark spot on the wall was actually just a shadow.
The bad news: the dark spots in the insulation are actually much larger.

Even as a layman, I recognized that the insulation was not done properly. The foil is not just a protection against dust but is the only thing still holding the insulation up. The insulation itself is largely black. A capacitive moisture meter showed 20% moisture for the roof beams. That's not an outstandingly good value but also not terribly bad. The beams looked okay in terms of substance. In the adjacent room (also unfinished), the ceiling insulation didn't look any better. All black. Even the real estate agent had to admit that it would have been better if they hadn’t installed any insulation there at all.
The attic insulation ("top floor ceiling") also shows slight signs of mold. What couldn’t be seen is what it looks like under the paneled sloping ceilings. Since at least one other room needs to be completely renovated anyway (smoking room and leaking roof window), the paneling can be torn out and the insulation redone completely.