: Great idea, I didn't know about foil sided insulation board. Was
: that the polyisocyanurate type which is good to 150C?
: Polystyrene is good to only 75C and I imagine it would melt . .
: .

Best stuff if you're going to use this is the industrial fiberglass board foil faced. It's rigid and pretty durable and heat won't bother it at all.

I just use a PVC tube that's hose clamped to a 2x4 so it doesn't deflect with heat. The screw on ends are handy.

Bill H.