Do we just go by the motto "the thicker, the better" or should we study this question more carefully?
The depth of the stock is 24 cm. If I decide to use insulation, should I also choose 24 cm or is there nothing fundamentally wrong with 18 cm insulation?
The latter would be quite inexpensive and immediately available to me, hence the question. 24cm would cost me about 50-60% more.
My understanding is that the insulation is visible from the attic, so there is no enclosed cavity between it and the microclimate of the pointed floor room. Then I think the thickness is negligible, and 18cm is still a big gain over what it used to be.