Insulation Near Chimney

[Vic99]

My stove is on the first floor of the house and my brick chimney is lined with an insulated 6 inch steel flue.

Looking up from my basement, I noticed that I have two different soccer ball sized holes between the first floor's flooring and the chimney. Can I stuff insulation there without having to deal with melting or combustion? I'd like to stop air flow, so I'd like to try and cut foam board and then cover it with fiberglass, just to be sure. Does that seem sound? Other suggestions?

Thanks

 

[humpin iron]

no flammables next to the chimney

 

[Wet1]

Use fiberglass insulation, no backing. If you're really concerned about it, use rock wool.