heat-resitant sound-proofing

[felix]

I have a space that has steam heat and the radiator goes from one room to the next. There is a space in there about 1 sq foot in all that needs to be filled with some kind of heat resitant sound-proofing material. Any ideas?

[goldstar]

Are you familiar with Wonderboard? It's a cement based tile backing board that comes in sheet form (usually 3'x5'x1/2" thick). Maybe you could use it, depending on the application.

Frank