Expert: James Ball - 2/24/2009

Question
my home was built in mid 60s as a ranch..in 80s a top floor was put on and in the process the chimney which is in the interior of home was extended and new exterior chimney built on the new roof. the chimney serves the basement boiler,basement fireplace, and main floor fireplace.(drafting is fine) An energy audit recommended that the chase be air sealed in attic floor(stop stack effect).there is a large space(1-2feet) around the chimney on all sides from attic floor to ceiling of first floor.insulator wants to fill it up with non flamable insulation and then air seal at top(fire stop etc)(attic floor) is this large gap all around serving any purpose(warming the uninsulated walls around?)is it good idea to fill this space up or should i just air seal and fire stop the top of chase(attic floor)..thank you for response and serving this board

Answer
hello /Charlie, depending on how the extended the chimney, was it brick? was it metal pipe? if metal pipe then you would have to refer to the owners manual for fire stops and clearance (most say do not insulate around the pipes)
I would have a local Certified Chimney Sweep (www.csia.org, there you can look up by zip code to find one near you) take a first hand look at what you have they should be able to help.