Room cold at the feet - Is basement ceiling insulation useful?

Has any of you ever bought B-stock (second choice) PUR/PIR insulation? You can definitely save a few hundred euros with it. What defects can be expected?

Yes. Broken edges, detached fleece (or corresponding aluminum). Nothing to worry about, especially when working with two layers. If working with only one layer, you should just make sure to use the rough edges only for border pieces, where you would cut off or fill the step joint anyway.

Oops wrong thread please delete

Has anyone of you ever bought B-grade (second choice) PUR/PIR insulation? You can definitely save a few hundred euros with it. What kind of defects can be expected?

20mm was not always fully foamed. 100mm and 120mm were just not perfect in size – sometimes a centimeter larger or smaller than intended. Otherwise, identical quality to A-grade. No damage, always fully foamed, no aluminum coating peeled off. With 120sqm for 20mm and 140sqm for 100 and 120mm, it was definitely worth it. That was more than just "a few hundred euros."

Hello everyone,
thanks again to everyone who helped me here with contributions, thumbs up!
The insulation is installed, everything worked out great. Now there are only two questions left:
- With the crooked walls in the basement, the wall finish is of course not always perfect, how should the resulting gaps be filled?
- Aluminum silver as a ceiling color is not exactly aesthetic (even if it’s just a basement). I assume you can't just paint these things white easily. Alternative? Wallpaper?
Best regards
N

What kind of insulation boards have you used now?
Stuffing stone wool - always works.