Need help with chimney installation

[westbrooklawn]

I am installing a Fisher Mama Bear woodstove in a detached metal building. The building is poured concrete slab (which is what the stove will sit on), and all steel construction including framing, walls, and roof. There is no ceiling in the building. The building is insulated with reflective foil insulation (silver against the outside panels and white facing the interior space). The stove has a 6" rear vent. My plan is to come out of the stove with a black single wall elbow, and then black single wall up to the bottom of the steel roof trusses. At this point I am thinking about framing (with metal) an area to mount a typical ceiling type chimney support, and then transitioning to an insulated chimney pipe which would go up through the metal roof with some sort of exterior pipe flashing, and then to the proper height above the roof, terminating with the proper chimney cap. Another option would be to run the single wall black pipe all the way to the roof, and then install a cathedral ceiling type chimney support, and then transition to an insulated chimney pipe which would go up to the final height and chimney cap termination. The length of black pipe in the first scenario is about 7'. The second scenario would add about 3' more. Do these approaches seem logical and safe? Would one be better than the other?

 

[dougand3]

The cathedral ceiling mount would be much easier. Just make a box between roof joists with metal 2x4s (or a heavier gauge). Pic is of a cathedral chimney system. See the brackets attached to 16" class A chimney - they screw into your constructed box.

 

[westbrooklawn]

Doug - Thanks for the reply... I like the idea of using the cathedral mount, plus it seems it would give me more heat in the building from the exposed single wall pipe. I just wasn't sure about the chimney being hot enough for proper draft, etc.

Now that you have helped me make up my mind about the way I want to go, what brand/configuration of chimney kit/pipe would you recommend. It would have to be something that would be readily available for the DIY'r... I wouldn't mind ordering online if I had to. Places like Lowes and Home Depot don't stock too much around here, and what they do have seems to be priced way too high. I am also looking for a recommendation on how to flash the chimney at the roof penetration... it is a ribbed roofing material, and the only kit I have seen online is like $200... there has to be a more economical way to flash that area. Thanks again for your help...

 

[dougand3]

When I searched for chimney - Oct 2008 - Selkirk Supervent at Lowes was the best deal. I got the horizontal ceiling support box kit and class A chimney there. (I didn't use the above Metalbestos). I don't recall seeing a cathedral ceiling support box kit, tho. I don't know how to flash a ribbed metal roof (search here - there have been threads on doing it)
10 feet of single wall stove pipe shouldn't cool gases off too much to disrupt draft. If you have a 30F building and stove - then light fire - probably won't draft so well till some heat gets in stove pipe and chimney.

 

[westbrooklawn]

Any one else have input or suggestions?

 

[snowtime]

As for that ribbed metal roof the cheap method is to use a spare piece of metal roofing that matches your current roofing. Cut it down to just be big enough to cover installation and it should stick about 2' above the chimney exit. Perhaps you have a piece laying around. What you do is get a cheap flashing kit with the right pitch mount it. Then mount the piece of metal roof above with silicone and screws. The bottom edge of the piece of metal roofing will over lap the chimney flashing and make it water proof. The spare roof piece will not be attached to the roof across the bottom only the top and sides will have silicone and screws. It will work like a charm.