Rockwool equivalent to 50mm thick foil backed foam board

[Tom079555]

Is there a table somewhere to show how foil backed board compares to rockwool?

I have 50mm thick foil backed board on my wall, but 200mm thick rockwool under my floorboards.

From a warmth perspective, how do the 2 compare?

Example: 50mm board is the equivalent of 300mm rockwool etc. (I've made this stat up, I'm just wondering if there is an answer)

Thanks

 

[^woody^]

Roughly twice as efficient.

 

[Tom079555]

So 50mm board is about the same as 100mm wool?

 

[JohnD]

That's about right.

Your floorboards probably have wool matching the joists thickness, which is easy. It's quite cheap. Most loss through wooden floors is by draughts, which wool will block if tightly stuffed in (easier to do than with foam boards) especially round the edges of the room where it is worst.