ᐅ Cold roof for storage purposes – membrane or fleece over the insulation

Hello everyone,

we want to cover our cold roof with wooden boards, leaving a 1cm (0.4 inch) gap between each board.
The floor/ceiling structure is insulated with un-faced mineral wool.
We are concerned that this might create a lot of dust, so we are looking for a membrane or fleece to act as a barrier, which we can staple under the boards.

What would be suitable for this purpose?

The floor/ceiling structure is otherwise built in a very standard way, from the inside to the outside: drywall, vapor retarder, mineral wool.

Thanks for any ideas and suggestions.

Check out Guckstdu https://www.hausbau-forum.de/threads/aufbewahrungsboxen-fuer-kaltdach.37546/ – the storage attic space of @Nordlys is probably mentioned somewhere there as well.

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It is indeed mentioned, and I believe @Nordlys also had a thread with many pictures about this, but I can't find it again. That thread was more about the retrofitting of roof insulation itself, ventilation, and so on... That might become interesting later.

For now, we are primarily looking for a dust-reducing separation between the mineral wool insulation and the floorboards.

I found a photo from Nordlys, where it looks like they installed tongue-and-groove boards as the flooring. Those are continuous.

We received some well-aged floorboards from relatives as a donation, and they are now going to be used in our attic. They will be laid with some spacing between them since they are not perfectly straight and to allow better ventilation of the insulation.

In my experience, this does not create dust. We did not cover the entire floor upstairs with tongue-and-groove boards, but only about 20 square meters (215 square feet). That is enough for our storage needs. The insulation around the edges is also left exposed.

You just have to avoid touching exposed mineral wool if you don’t want it to create dust. With the same construction setup in our house, it even produced dust when there was movement on the panelled area. I should put something on the still exposed mineral wool. In my previous house (a listed building), I used a type of black fabric—like the one used to cover the sides of bowling alleys—because it is very permeable. That worked quite well and didn’t cause any building damage, but there’s probably something more suitable. I would appreciate any recommendations!

It would be beneficial, when using well-seasoned wood, to make sure you’re not introducing pests. Also, if the house is still new and work needs to be done, I would not only lay the boards with gaps but also fasten them only in one spot.

Wishing you all a Thanksgiving Day to mindfully appreciate your harvest.

It’s quite dusty in our attic under the flashlight, and the floorboards haven’t been laid yet. Thanks to @fach1werk for the tip on fastening. The house is new, and the roof structure has been in place since May. But how can we be sure that there is no life in the floorboards? Besides just inspecting them visually?

I just found the ProClima dust protection membrane. It’s made of polypropylene (PP), triple-layered, especially durable, dust-tight but not airtight, and highly vapor-permeable…
sd value 0.03 m (0.1 ft)

It is usually used to be placed under the insulation in floors with loose-fill insulation.

Based on its properties, it sounds good, but since PP is a plastic, how much moisture can actually escape?
According to online sources, an sd value below 0.5 m (1.6 ft) is considered vapor-permeable, allowing water vapor to pass through freely.

Does anyone have practical experience with this membrane or can suggest another membrane suitable for this application?