Foam plastic instead of insulation?

[fredand44]

Hello!

I was wondering if foam plastic works as insulation between/in garage ceilings and loft floors? (That is, between two floors) I hope to turn the loft into a guest cabin.

The reason I'm asking is that I accidentally bought 4 bales of foam plastic thickness 50mm at byggmax.

Now I'm sitting here with my four bales and don't really know what they can be used for, the area is about 40 sqm.

But maybe foam plastic doesn't have the same insulation value as real insulation?

Thanks a lot for the tips.

Best regards,
Fredrik

 

[Watchmen]

It has a better insulation value. And I would probably classify cellplast as real insulation
But cellplast is the insulation material that burns the easiest.
Therefore, it is usually only used in places that are protected from fire and heat, such as the foundation, plaster, etc.

 

[fredand44]

Thank you!

Could it be so bad that one should not use cellplast as insulation in walls and ceilings at all due to the fire risk?

Best regards,
Fredrik

 

[snuttjulle]

If I remember correctly, the k value is not better for cellplast than regular mineral wool. And if you consider that cellplast is harder to seal around studs, etc., you lose in total k value. I don't care about the fire risk as my house would burn down in a few minutes since it's a wooden house from the '50s and it's dry, you should know.

 

[Watchmen]

I fix the tightness by always buying the sheets 5mm larger and pressing them in.
As the U-value of the lowest cellplast is 0.038 and the best is 0.033.
I will use cellplast in both the ceiling and walls. However, there are sw elements and hd-f decks as intermediate floors and as the ceiling. Therefore, I get a high fire rating.