Work on basement ceiling insulation with stone wool

10cm PUR (WLG 025, aluminum laminated) has 0.235 W/(m²K). Fleece laminated (WLG 028) would have 0.261. 14cm stone wool (WLG 040) has 0.266 W/(m²K).

Can this be used in 100mm for basement and upper floor ceiling? Is that sufficient?

I do claim that, but I am not an expert either. Maybe ask the [Energieberater] again.

Where can you get 2nd choice stuff?

well, my google still works? Is yours broken? "pur pir 2.te wahl" as search terms in combination yields an almost perfect result.

Where can you get 2 component stuff?

I always go to Dämmstoffkönig or Smartbau in Nettetal. Depending on what I need. From PUR/PIR to mineral wool to Resol. You should look it up online – I’m not allowed to post links.

I always go to Dämmstoffkönig or Smartbau in Nettetal. Depending on what I need. From PUR/PIR to mineral wool to resol. You have to look it up online - I’m not allowed to post links.

Yes, I found those two as well. But the drive is not worth it, it’s unfortunately not that cheap. It would be about 150 km one way.

But the trip is not worth it, it's unfortunately not that cheap.

Roughly half the normal price on the internet you call "not that cheap"? LOL - I'm lost for words. Sure, compared to free it's definitely more expensive (and also adds more). That's true and I understand that. Overall, though, these are amazing prices for a product where you often don't even notice why it’s second choice. But in return, you get insulation and not homeopathy like with your initially considered 30mm mineral wool. The 100mm PUR also makes your basement ceiling roughly a KfW55 basement ceiling, which of course makes an extreme difference.