Roof insulation? Which options/variants make sense?

Hello Borderpuschel, Thank you for your response. Would you also do without the [Untersparrendämmung]? I wanted to use 120mm [Klemmfilz] and 50mm [Untersparrendämmung]. Both with 035 Wlg.

rather significantly more... 170mm insulation is nothing for a roof.

Is it CERTAIN that the roof will be re-covered in the next few years? If it is damaged, it should be fixed immediately, and if not, why should it be damaged in five years?

In general: After removing the old insulation, check all roofing felts for tightness or proper fit. If there are corners hanging loose, water will drip in during heavy rain. With an open roof space without insulation, this is not a problem. With underlying insulation, it’s not so nice. It’s best if you already pay attention to damp/moldy spots when removing the old insulation. You should then immediately make repairs there. Fortunately, roofing felts can be replaced individually.

Maintain ventilation under the roofing felts with 2, preferably 4 cm distance. For compressed fleece with limited build-up height, it’s best to use WLG032, but 035 is not a big deal nowadays and doesn’t make much difference in the end.

Insulation below the rafters if there is space. Whether EPS composite board or battens and board on top doesn’t matter at the end of the day. Mineral wool is easier to process in corners and hard-to-reach areas. Thickness depends on the available area. If you end up with 24 cm (with insulation outside), it doesn’t change much beyond that.

Hello "dertill",

thank you very much for your explanation. So far the roof is still in good condition. The re-roofing is planned for later, as it is a semi-detached house to achieve a uniform appearance here. Would the effect be the same if I double the rafters and dispense with the insulation below the rafters? Of course, with the same total insulation thickness. Since we are going to tear down the entire inner construction of the roof anyway, doubling would also be possible without problems. I would then go with 180mm compressed fleece in 035 and later take 60mm Staico panels from the outside.

Today the roofer advised against combining an insulation between the rafters with an insulation above the rafters, as this is problematic due to the dew point between the layers. Is there any truth to that? Ubakus also indicates this to me, but as a layperson I initially ignored it. I was simply advised to use 200mm insulation between the rafters with a double layer of drywall.

what does double drywall panel mean?