Expert: Bart Ogden - 3/3/2008

Question
QUESTION: I am having a new house built and have a metal Chimney going up through the interior of the house that will be enclosed by wood frame with dry wall.  The builders plan is just to insulate the exterior walls and not the framed enclosure around the metal chimney.  So when the fireplace is not in use there will be a cold chimney that will leak cold out through the dry wall.  Should I insist that he insulate around the frame enclosure while still maintaining the 2" clearance that the steel chimney requires?  My other thought (in addition to avoiding the cold air coming from the Chimney into the house is that it will also prevent warm air from the house coming through the drywall and warming the chimney which I would think would cause the chimney to not draft as well.  Any recommendation would be greatly appreciated as I don't know that I have a very good understanding of how a chimney should work and whether the insulation would be a good or bad thing.  Thanks!

ANSWER: Hi David,

The framed enclosure should be thoroughly insulated to extend the building envelope around the chimney.

It must be insulated and maintain the minimum clearance to combustibles.

My advice is to also install roughed-in drywall to retain the insulation inside the chase.  It will also prevent more air infiltration from the exterior.

Warming the chimney is good and will promote good draft.  If you'll leave the wall space between the house and the chase uninsulated, you'll get a warming effect on the chase and have better luck establishing and maintaining draft from startup through tailout.

Thanks for using AllExperts.Com and good luck with your project.

Sincerely,
A. Bart Ogden, President
Home Safe Hearth & Chimney, Inc.
Wichita, KS
Voice: 316-265-9828
Fax: 316-265-9890
www.homesafeks.com


---------- FOLLOW-UP ----------

QUESTION: Hello Bart,  Thanks for the answer but I was wondering if you could clarify the last paragraph.  In the first few statements it seems clear that you were suggesting insulating all the way around the chimney to keep cold from the chimney from going through the dry wall into the room.  That I understood.  So if I understand what you suggest there should be insulation between the 2x4's of the frame around the Chimney with dry wall on both sides (front and back) to keep the insulation between the 2x4's.  The area enclosed by the frame (which I believe you are referring to as the Chase would be a hollow cavity with dry wall enclosing it and the metal chimney would run up the middle of this cavity/chase.   In the last paragraph you say " If you'll leave the wall space between the house and the chase uninsulated you'll get a warming effect on the chase and have better luck establishing and maintaining draft from startup through tailout." I am having trouble understanding that compared to your first statements.  This last statement seems to indicate that I should not insulate around the frame/walls around the chimney/chase.  Can you clarify?  Thanks again for your help.

Answer
Hi David,

Insulate around the two sides and back of the chase.  Leave the wall between the chimney and the living space uninsulated.

Thanks for using AllExperts.Com and good luck with your project.

Sincerely,
A. Bart Ogden, President
Home Safe Hearth & Chimney, Inc.
Wichita, KS
Voice: 316-265-9828
Fax: 316-265-9890
www.homesafeks.com