There appears to be some sort of gap where my wood burners flue comes out through the roof that is allowing rain water to travel down the exterior of the flue pipe and then drip down the cavity space where the flue goes down to the log burner. This is now causing visible water damage to the flue surround as it enters through the ceiling above the log burner. I am thinking I can just throw some expanding foam into the space between the flue and the surrounding area as it comes out to the roof but obviously am abit lost as to whether this is even a good idea and to what grade of heat resistantance I need. The section I'd be filling is well away from the burner itself but obviously still does feel warm to the touch when the burner is on. It's a standard 2 floor house with the burner being on the ground floor.
I'm a complete novice so any help will be appreciated and apologies if I've missed off some basic information that would be pertinent.