Comparing fibreglass insulation to solid.

[Lex Foutish]

What thickness of aeroboard (or similar type) insulation would have similar insulating properties to 200mm fibre glass type insulation?

 

[VByrne]

Hi Lex,
If you keep it in a hot box in a lab, then about 80mm of closed cell foam, when you take it out then there is no comparison, for when exposed to air movement mineral fibre is outside of it's steady state and has no control over air movement, so the value drops off by a vast amount, but the foam is still in a steady state so air movement has no effect, this applies to all fibrous materials that's way they need air-barriers, I hope this helps

 

[durafoam]

Spray Foam Insulation is another option-- I know you didn't mention it and it's a more expensive solution. However, in my experience, a single inch of closed cell spray foam is better than 4 inches of fiberglass. Part of this is due to the fact that it creates a seamless monolithic barrier. It's an excellent sound barrier as well...