What are the fire rating properties of expanded polystyrene and rock and wool insulation?
Gosh, I couldn't say...but, if you're asking because you're
trying to choose which one to use I have to say DONT use
polystyrene..not in the loft anyway! In the loft, the beads will
attach themselves to your wiring, over time, and eat their way
through them. And are a fire hazard. BUT, if it's for in your
walls, I believe polybeads have a higher u-value thus insulate
better. Rockwool is a very good product though, been around for
decades, is inert and also used in hospitals (internal walls) to
stop the spread of fire.