Do I "really" need to build an insulated enclosure around a DuraTech chimney?

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burro child

New Member
Nov 23, 2021
10
South Portland, Maine
Greetings:

I apologize if this has been covered elsewhere in these forums--seems like it would have been--but multiple searches yield no directly applicable results.

DuraVent says that:

"In cold climates, chimneys mounted on an outside wall should be enclosed in a chase. Exterior chases reduce condensation and creosote formation, and enhance draft. Include an access door by the Tee Cap for chimney cleaning.”

I am in a cold climate, in southern Maine. We are planning to install a Jotul F3CB wood stove as a part-time space heater in a poorly insulated sun porch that juts off of our home. Stove will be back-vented through the wall to a DuraVent (likely DuraTech) chimney running 23’ 5” — terminating 6’ 9” above the second-story roof:

chimney.png

We plan to burn only well-seasoned high-quality firewood and to regularly clean the chimney. Given that and the length of the run:

Do I really need an exterior chase?

(The Fire Marshal will have the final say, of course, but I'm interested in what y'all have to say about it in the event that they leave it up to us).

Thank you!

Stokes
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
30,254
central pa
Greetings:

I apologize if this has been covered elsewhere in these forums--seems like it would have been--but multiple searches yield no directly applicable results.

DuraVent says that:

"In cold climates, chimneys mounted on an outside wall should be enclosed in a chase. Exterior chases reduce condensation and creosote formation, and enhance draft. Include an access door by the Tee Cap for chimney cleaning.”

I am in a cold climate, in southern Maine. We are planning to install a Jotul F3CB wood stove as a part-time space heater in a poorly insulated sun porch that juts off of our home. Stove will be back-vented through the wall to a DuraVent (likely DuraTech) chimney running 23’ 5” — terminating 6’ 9” above the second-story roof:

View attachment 289518

We plan to burn only well-seasoned high-quality firewood and to regularly clean the chimney. Given that and the length of the run:

Do I really need an exterior chase?

(The Fire Marshal will have the final say, of course, but I'm interested in what y'all have to say about it in the event that they leave it up to us).

Thank you!

Stokes
No you don't need one but they certainly do help keep temps up in the chimney
 

firefighterjake

Minister of Fire
Jul 22, 2008
19,593
Unity/Bangor, Maine
If it helps I am about 1 to 1 1/2 hours north of you and I have an exposed Class A chimney running from the first floor to above the roof in the second floor without a chase. I was going to build a chase simply for the aesthetics, but then realized one day that due to the lay of the land and house you pretty much cannot see the chimney from the road except for a little bit at the top. I have noticed no issues in 13 or so years of heating . . . other than it's really easy to do a clean with a T connector on the outside.
 
Oct 13, 2020
167
Quebec, Canada
I have 24 feet of 6'' dia. insulated outside chimney and no chase, I already have excessive draft so certainly do not want to enclose it to obtain even more chimney draw, esthetically it would look better however, operation wise not needed at all.
 
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burro child

New Member
Nov 23, 2021
10
South Portland, Maine
If it helps I am about 1 to 1 1/2 hours north of you and I have an exposed Class A chimney running from the first floor to above the roof in the second floor without a chase. I was going to build a chase simply for the aesthetics, but then realized one day that due to the lay of the land and house you pretty much cannot see the chimney from the road except for a little bit at the top. I have noticed no issues in 13 or so years of heating . . . other than it's really easy to do a clean with a T connector on the outside.
To save money, we are going to move the stove location to get >10’ from the main structure and go straight out the roof…. Won’t have to build a chase and will use far less pipe!!! Appreciate everyone’s responses here…
 
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