Venting Stove Through Metal Roof

[Coolerman]

I'm back with more questions!

I have a 24 x 40 foot insulated (3" fiberglass plastic faced) all steel building that is 14' at the peak.

I am about to install an old Kodiak Stove wood burner I picked up for $100. I am modifying the stove by adding a secondary air combustion system to increase efficiency and burn time, will reline it with new fire brick, and give it a fresh coat of high temp paint. This is a large stove(actually it's a fireplace insert) that can burn 24" logs so it should have no trouble heating my shop. It is also double walled so if needed I can install a squirrel cage fan on the bottom to blow air out the top for additional heat

I plan to mount it about 20" off the floor for ease of loading and to prevent any fumes that might occur from spilled fuel or whatever from reaching the stove. The shop is not super sealed so I really am not worried about that issue.

What I plan to do:
I will use 8" DuraVent DVL (double wall black pipe) from the stove up to 18" away from the ceiling. I will then put a DVL to chimney adapter on the end of the DVL. Next I will cut the insulation back to 6" clearance then penetrate the roof using the Duravent Chimney pipe (stainless double wall) to the height above the peak required by code. To seal it to the metal roof
I will install a red silicon boot (high temp) covered by a storm collar to help protect the boot. Last will be a stainless cap on the chimney. So does that sound like it's correct? Am I missing anything?

Another question is this: The total length of pipe including the chimney will be about 16'. The entire weight of the pipe in the above plan will be on the stove collar. Do I have to support the pipe in any way INSIDE the garage? Does the chimney section have to be self supporting?

 

[Lippyp]

I'm doing something similar but it's going through a slate roof. My plan is a metre of single wall pipe with an access door for cleaning and maybe a chimney damper for extra control, then insulated twin wall the rest of the way up and out. The bottom part will be supported by the stove and there will be a clamp attached to the joists to support the top section before it penetrates the roof, it'll go through a rubber boot, storm collar on pipe above this and then a cowl on top. I do have a wall clamp so that might well go on halfway up for extra support. Mines around the same length toal as yours at 5M.

My chimney on the one in France I put in has single wall stainless to the ceiling at 9', then an adaptor plate bolted to the oak beams, above that it's double wall into two 45* bends to shift it over to miss the ridge beam and up again and out. Again a support collar at the roof joists, flashing, stormnm collar and cowl.

Sounds to me like you're on the right track.

 

[Charles (in GA)]

This may help.

http://www.duravent.com/docs/L820_W.pdf

You do not want the weight resting on the stove.

charles

 

[smokem2020]

I mounted my boot on the under side of my metal roof. I just couldn't figure out how to get around the ribs on the steel and make it look right and lay flat.. I pinched the ribs on the metal together and used silicone to seal the seams.

 

[BigGMC]

Hey! I have the same stove, but not an insert model......... and its not hooked up yet....

I dont know about Duravent products (I've got Selkirk) but there should be a piece called a roof or ceiling support. That piece will hold and distribute much of the chimney wieght to the surrounding roof structure. Might have to do some extra boxing/bracing between rafters/trusses since you have a metal roof.
There is also usually a piece you can get that provides a proper airspace around the chimney as it passes up into the insulated cieling.
Make sure the exterior part of the chimney is braced to the roof - I think they recommend anything 4' and taller to be braced. With your metal roof, snow will certainly push on the chimney.

 

[Coolerman]

This may help.

http://www.duravent.com/docs/L820_W.pdf

You do not want the weight resting on the stove.

charles

Thanks, that was a very helpful link!
Looks like the part I forgot was the ceiling support. I'll have to make a metal frame to go between the roof trusses for the ceiling support to mount to. I also added the double wall pipe to stove adapter with a built in damper.

That brings my total to about $1400... Seven times the cost of the stove! (I figure I will spend another $100 modifying the stove.)

Now I get to shop around for the best price on this stuff. The above total was from Woodland Direct... Lots of places seem to carry this piping including Home Depot. Unfortunately they don't stock the 8" at my store...

 

[Coolerman]

Hey! I have the same stove, but not an insert model......... and its not hooked up yet....

I dont know about Duravent products (I've got Selkirk) but there should be a piece called a roof or ceiling support. That piece will hold and distribute much of the chimney wieght to the surrounding roof structure. Might have to do some extra boxing/bracing between rafters/trusses since you have a metal roof.
There is also usually a piece you can get that provides a proper airspace around the chimney as it passes up into the insulated cieling.
Make sure the exterior part of the chimney is braced to the roof - I think they recommend anything 4' and taller to be braced. With your metal roof, snow will certainly push on the chimney.

Yep, figured out the ceiling support piece from the link that was posted. I'm just going to trim the insulation back to the required clearance and tape the edges down. This is getting pretty expensive for a shop stove! I know I could use single wall pipe up to the chimney, but my luck something would fall against it and catch on fire while I was not there.

Any suggestions on doing this cheaper while keeping safety in mind would be very much appreciated!

 

[Coolerman]

I mounted my boot on the under side of my metal roof. I just couldn't figure out how to get around the ribs on the steel and make it look right and lay flat.. I pinched the ribs on the metal together and used silicone to seal the seams.

The silicon boots I found have a deformable metal base. http://www.bestmaterials.com/detail.aspx?ID=14994

A thick bead of Urathane sealant on the edge of this base then a hammer to mold it to the ribs of the roof. (Another option uses butyl tape around the base edge.)

Roof screws with rubber washers every 1 1/2" around the edge then a bead of sealant around the entire edge where it contacts the roof. Finally a dab of sealant on the screw heads to seal them and it should never leak.

 

[Lippyp]

It stings doesn't it when the flue costs way more than the stove, my stove cost £100, and I've got close on three times that in the flue already even buying everything used, just picked up a metre length of 6" single wall stuff with an access door for sweeping it, brand new but some of the black enamel is chipped off, half price at £22. Gonna stick a damper in that section as well. Still need to buy the roof support new and the flashing kit.

 

[Charles (in GA)]

Thanks, that was a very helpful link!
Looks like the part I forgot was the ceiling support. I'll have to make a metal frame to go between the roof trusses for the ceiling support to mount to. I also added the double wall pipe to stove adapter with a built in damper.

That brings my total to about $1400... Seven times the cost of the stove! (I figure I will spend another $100 modifying the stove.)

Glad you found the catalog useful. Seeing the entire product line, and having illustrations of how they are used, I find, is most helpful.

I keep telling people who complain about the price of a new used/waste oil heater like mine, that the chimney system is about $1500 of the cost for the heater, they don't seem to believe me, but as you have discovered, it is true.

Charles