Installing a Metal Chimney in a Barn

[Paul_NJ]

Hello Again

Just found this site - glad to discover such a helpful resource!

When I reroofed my barn-converted-to-workshop several years ago, I anticipated a wood burning stove in the future, and installed a conical flashing piece to the new roofing before putting down the shingles. It has an 8" opening. The stove sits right in the center of the barn, and the pipe goes straight up to the roof. The used woodburning stove I recently purchased (Timberline) has a 8" opening.

Problem: I now realize I can run 8" stovepipe the 12 feet up to the roof, but must transition to a 4 foot length of double walled chimney pipe piece thru the roof and out. Problem is that in order to keep an ID of 8" all the way, the OD of the chimney pipe goes to 10". Not wanting to tear up my roof to put in a 10" flashing cone, is there any reason why I can't cut off as many inches of the existing cone as necessasiry to increase the opening to 10"?

Hope I described this well enough. I'd appreciate any thoughts and help.

Paul

 

[babalu87]

I wouldnt mess with a roof

Selkirk makes an 8" OD pipe but the through wall fitting they give you requires a bigger hole
I believe all through wall/ceiling pipe installs require a 2" airspace around the pipe
The fitting/collar for mine was a big hole over a foot

 

[webbie]

Hello Again

Just found this site - glad to discover such a helpful resource!

When I reroofed my barn-converted-to-workshop several years ago, I anticipated a wood burning stove in the future, and installed a conical flashing piece to the new roofing before putting down the shingles. It has an 8" opening. The stove sits right in the center of the barn, and the pipe goes straight up to the roof. The used woodburning stove I recently purchased (Timberline) has a 8" opening.

Problem: I now realize I can run 8" stovepipe the 12 feet up to the roof, but must transition to a 4 foot length of double walled chimney pipe piece thru the roof and out. Problem is that in order to keep an ID of 8" all the way, the OD of the chimney pipe goes to 10". Not wanting to tear up my roof to put in a 10" flashing cone, is there any reason why I can't cut off as many inches of the existing cone as necessasiry to increase the opening to 10"?

Hope I described this well enough. I'd appreciate any thoughts and help.

Paul

I don't see a big problem with that....BUT, you have to cut it to over 10", something closer to 11". The storm collar then makes it rain proof - the idea here is that flashings don't fit tight so they allow excess heat buildup along the outside of the pipe to be ventilated upwards.....sealing the pipe tightly at the roof could possible create an overheat situation...although somewhat unlikely in your case. Also, the insulated chimney should extend downward into the room at least 18" and preferably a little more. If you have ceiling joists that are level, the insulated pipe should extend to well below these.

 

[BS-N]

Maybe it is simpler to by a stove with a 6" outlet.

 

[Metal]

I, personally, would bite the bullet and put in the larger flashing. You will be glad you did it in the long run. BTW, Metal-Fab's 6"-8" Temp/Guard Chimney has only 1 1/2" Clearance to Combustibles.

 

[babalu87]

Maybe it is simpler to by a stove with a 6" outlet.

My Morso 3610 requires a 6" ID stovepipe and chimney

The through wall collar that Selkirk supplies with the through wall T-kit took over a 12" hole
ANYTHING going through a combustable wall requires an airspace around the pipe (provided by the collar)

I had the added luxury of having a header meant for a fireplace in my way
Thankfully my brother lives close enough AND had a Sawzall :coolsmile:

 

[Paul_NJ]

Hello Again

Just found this site - glad to discover such a helpful resource!

When I reroofed my barn-converted-to-workshop several years ago, I anticipated a wood burning stove in the future, and installed a conical flashing piece to the new roofing before putting down the shingles. It has an 8" opening. The stove sits right in the center of the barn, and the pipe goes straight up to the roof. The used woodburning stove I recently purchased (Timberline) has a 8" opening.

Problem: I now realize I can run 8" stovepipe the 12 feet up to the roof, but must transition to a 4 foot length of double walled chimney pipe piece thru the roof and out. Problem is that in order to keep an ID of 8" all the way, the OD of the chimney pipe goes to 10". Not wanting to tear up my roof to put in a 10" flashing cone, is there any reason why I can't cut off as many inches of the existing cone as necessasiry to increase the opening to 10"?

Hope I described this well enough. I'd appreciate any thoughts and help.

Paul

I don't see a big problem with that....BUT, you have to cut it to over 10", something closer to 11". The storm collar then makes it rain proof - the idea here is that flashings don't fit tight so they allow excess heat buildup along the outside of the pipe to be ventilated upwards.....sealing the pipe tightly at the roof could possible create an overheat situation...although somewhat unlikely in your case. Also, the insulated chimney should extend downward into the room at least 18" and preferably a little more. If you have ceiling joists that are level, the insulated pipe should extend to well below these.

Craig

I appeciated you're answering my question. This is a great site - I just found it today and I'm really impressed!

It dawned on me that I'd better check to make sure a 10" chimney passing thru the "opened up" 8" flashing has enough heat clearance to the edge of the cut out hole in the roof plywood, as that hole size was intended for an 8" pipe.

Thanks again

paul