What type of attic insulation is sensible?

Hello everyone,

I am new here and came across this site through various search queries. Although I have already read quite a bit about insulation, etc., I still don’t know what I should do in my case, so I registered here.

Last year in the spring, I bought an apartment (top floor). I am currently completely renovating it. Originally, the plan was to just do a bit of whitewashing and then move in. Well... now I have torn out the entire floor, installed an additional door, and am currently installing several ceiling spotlights. One thing led to another... I think some of you here can relate to that.

Since I live at the very top and wanted a few ceiling spotlights, I naturally also went up to the attic. Of course, the attic is ideal for installing spotlights, as I can easily reach everywhere from above to lay cables. So far so good... the first spotlights are installed and look very good. What looks less good, however, is the attic in general or rather what is called "insulation" there. The previous tenant mentioned that the apartment is fairly cool in winter, which doesn’t surprise me at all after seeing the attic.

The attic is constructed and insulated as follows: The ceiling is about 2 cm thick and made with a kind of reed as a carrier material. This ceiling is then attached to the cross beams with about 2 cm thick slats laid lengthwise. After that, there is basically nothing. After about 8 centimeters, there is a wooden strip on which small boards lie (to close the gaps between the cross beams). On these boards lies about 3 cm thick fiberglass insulation, which looks terrible due to all the dirt and dust. I hope this is somewhat understandable.

The roof is continuously insulated under the roof panels with Styrofoam inserts (Thermodach). But the insulation or the construction of the attic is very sparse. I am not surprised that a lot of heat is lost here.

Since I definitely don’t want to leave it like that, the question now is how to best properly construct and insulate it.

I had the following in mind: Remove all the fiberglass insulation (it’s soaked and dirty). Clean everything. Remove all boards between the cross beams and clean everything thoroughly there as well. Then put in 20 cm thick insulation wool between the cross beams and close it off with chipboard or something appropriate (so you can walk on it). Here I still have the question about a vapor barrier (yes/no) under the insulation and how to best lay it. I can’t go under the cross beams, so I would probably have to seal each segment individually, right?

I would be very grateful for tips and suggestions.

Here are some pictures:

Hello,

a question in advance:

Did you buy the attic with the property, or are you currently working on common property?

If it has not been approved by the owners' meeting, this can backfire very quickly.

Regards,

Dirk

Yes, if I were to insulate there, I would also attach the insulation directly to the ceiling. That is how it is done in our house as well:

- Mineral wool "pushed" directly between the rafters and a walkable plank floor laid on top.

- Under the roof tiles, an additional insulation made of wood fiber boards.

Yes.. that's how I imagined it. Just a quick question (I'm not doing anything yet): Does a vapor barrier need to be installed under the [Mineralwolle]?

Under our mineral wool, there is a vapor barrier fleece. Therefore, I would also recommend installing one there with you,

So.. I discussed it with the property management yesterday. As long as the statics are not affected, I am allowed to install spotlights there.

I also spoke with the owners' advisory board. The topic of insulation has come up quite often in the past. However, it was always rejected by the owners due to the costs (often when it does not affect most of the owners themselves). But if I bear the costs myself on my own, I am allowed to do something about the insulation. Since it concerns my apartment and it simply bothers me now, I will do it.

So everything is clarified. Now it’s about what I do most sensibly and how I approach it best. Disposing of the glass wool is not so easy either. Disposable suit, mask, special bag is clear. But is there anything else to consider? How do I get all the dirt and dust out of there? With an industrial vacuum cleaner? With a broom and dustpan you would probably stir up a lot of dust and fibers, I think..