best chimney design for a steep pitch

[m camp]

Hi, I'm just building a small house with a 14:12 pitch gable roof. The floor layout is pretty much fixed at this point, with the woodstove going in a corner of the house. To get my two feet above a ridgeline within 10 feet, I'm going to have to extend the stove pipe 2 feet above the actual house ridge line. There is a half-story / living space loft above the woodstove with a sloping ceiling...ie there is no attic space.

Would it be best to...

1) Run the pipe straight up from the stove? This leaves me with an awkward, long stack of something like fifteen feet above the roof. Might be hard to guy and support, and it's also going to be cold which could cause creosote / poor draft etc..

2) run the pipe straight up to the loft space and then angle it below the insulated ceiling to exit closer to the ridge line? this keeps the pipe warm and gives a less tottering stack outside..but now i've got two bends in the pipe, will they be a real nuisance to clean or restrict the draft too much?

thanks for any thoughts

 

[begreen]

It would be best to try hard to locate the stove more centrally in the house, especially if this is new construction. It will look and function better both for heating and draft. Our friend had a similar situation in his A-frame and took this advice. He ran it up thru the loft just off of the main loft corridor and it worked out well. In this type of construction a ceiling fan is a must.

 

[barnaclebob]

I'm not sure that keeping your pipe warm is really that big of a deal. It may take only an extra couple minutes to get the inside of the pipe warmed up relative to having it inside. Air from inside your house will also being going up it keeping it a little warmer under most cases.

I think you'll get better draft with the straighter pipe and there are methods to support long pipes above the roof.

What might matter most is how ugly it will be.

For the inside routing option will you be able to have the chimney angle match the roof angle and will the clearances make it look ugly? Cleaning shouldnt be that much more difficult with 2 45's in the stack.

 

[m camp]

Yes, understood about the stove location...but that option really isn't available at this point, working within a very constrained almost-tiny house layout and need to accommodate stairwells and access, etc...

Still wondering, of the two options presented, which is the lesser of two evils?

I've read elsewhere about cooling of external chimneys leading to reduced draft and creosote. It is routinely -20F here..

( there is a full ceiling and regulation stairwell for the main floor, bedroom lofts have doors...so I think closing those doors will help regulate the upstairs temp...perhaps a ceiling fan in the stairwell might help , or a curtain at the stairwell entrance..)

 

[Ludlow]

Build a dormer in the roof and run the chimney up through it. Make it large enough to offer a window for the living space as well. What I would do. 15 feet of guyed pipe looks hideous. Offsetting more than a few feet is asking for problems.

 

[begreen]

Your concerns are valid. 15' of chimney will not only look like a silver rocket, it will be harder to brace as well. That's important if there are heavy snow loads on the roof and high winds. Sounds like your best bet will be to use double-wall stove pipe inside and use a 45º offset to start following the roof line, then 45º again to a cathedral roof support. I'd put a hanger strap or two on it for peace of mind. Clearances will need to be watched, some 6" d-w stove pipe needs 9" clearance from the ceiling, but that will get it higher up on the roof. The sloped pipe offset should draft reasonably well.

 

[Ludlow]

Your concerns are valid. 15' of chimney will not only look like a silver rocket, it will be harder to brace as well. That's important if there are heavy snow loads on the roof and high winds. Sounds like your best bet will be to use double-wall stove pipe inside and use a 45º offset to start following the roof line, then 45º again to a cathedral roof support. I'd put a hanger strap or two on it for peace of mind. Clearances will need to be watched, some 6" d-w stove pipe needs 9" clearance from the ceiling, but that will get it higher up on the roof. The sloped pipe offset should draft reasonably well.

He isnt working with an open cathedral. It is living space above. You cant pass stovepipe through floors.

 

[m camp]

ok, thanks so much for the thoughts... i've already framed in two tiny shed dormers but they are too far away from the gable end for running chimney there... i think i'll go with the double wall pipe angling up to the cathedral support. Sounds like a spendy amount of pipe to buy but what can you do? thanks for the tip on clearances. The ceiling angle is almost 49 degrees so I suppose two 45's would be close enough. The offset could be somewhere between four and six feet horizontally and it would help things a lot. Is there a critical value where I'd be asking for trouble or are those reasonable distances?

the fifteen foot rocket was a bit of an exaggeration, but it would have been pushing twelve feet i'm sure

 

[Highbeam]

You need roof supports for every five feet. So no less than two pairs of braces for 15’. It’s not just the crazy rocket look but the scaffolding look too.

 

[m camp]

really? i can't pass it through the floor of a living space? can you just box it in and take up half your bedroom? ok i'm off to read through my local regulations again, this just got more complicated

 

[bholler]

really? i can't pass it through the floor of a living space? can you just box it in and take up half your bedroom? ok i'm off to read through my local regulations again, this just got more complicated

Yes you can pass it through the floor. But when you do that you need to switch to chimney pipe.

 

[m camp]

got it, thanks

 

[begreen]

He isnt working with an open cathedral. It is living space above. You cant pass stovepipe through floors.

He said loft, so i assumed the pipe traversing open space. If it has to pass thru a floor then of course it must become chimney pipe. This sounds almost identical to the issue my friend had with his a-frame. We set the stove more center in the house and brought it up thru the floor with a ceiling support box.

m camp, a sketch or two of the floorplan and maybe an elevation can be worth a hundred words here.

 

[Ludlow]

Yes, switching to chimney pipe will work. I referred to using stove pipe as was said. However, It will not be parallel to the pitch of the roof using 45's. A 14/12 is a 50 degree angle. Just know that going in.

 

[Highbeam]

Yes, switching to chimney pipe will work. I referred to using stove pipe as was said. However, It will not be parallel to the pitch of the roof using 45's. A 14/12 is a 50 degree angle. Just know that going in.

Are you even allowed to use 45 degree bends in class a?

 

[AlbergSteve]

Are you even allowed to use 45 degree bends in class a?

Yup, that's what they make 'em for... this is my last place.

 

[begreen]

Many chimney mfgs. only make 15 & 30º elbows, no 45s.

 

[m camp]

Sorry my bad, I call it a loft or half-story as it's not a true second story, but there is a full ceiling across the main floor. The layout of the place is very small, efficient and boat like, I really don't have wiggle room to move this stove to another location...there is timber framing / interior posts / utility layout / traffic flow / entrance porch and a stairwell tucked into a dormer and if I move the stove more than a foot or two the thing isn't going to work.

I think I'll have to just buy a bunch of insulated pipe. Two 45's. The pipe is going to be 4 degrees off from the ceiling. I think I can live with that. It might drive my partner insane.

Is there a setback for insulated pipe from mineral wool batt insulation?? The 'loft' ceiling is over a foot thick ( 2x8 rafters and then little gussets that hold a 2x2 inner rafter for ceiling attachment...it allowed me to get adequate insulation space)... If there wasn't a set back from mineral wool I could maybe partially recess the insulated pipe into the ceiling and box it, and save some interior room / bedroom headroom and space. Rafters are on 24's.

 

[m camp]

*&*)& those are expensive, that's like 800 bucks canadian in elbows...

 

[AlbergSteve]

Selkirk Ultimate One says their 45's are listed for use/sale in Canada only. And watch the offset, Selkirk for example limits offset to six feet.

 

[AlbergSteve]

*&*)& those are expensive, that's like 800 bucks canadian in elbows...

With tax, pretty close...

 

[m camp]

just walked out there, i think i could put the 45's right off the stove on the main floor in regular stove pipe and save 700 bucks, it would shift the chimney over one timber frame 'joist' space on the loft floor and make a much more favourable roof exit, maybe a six or seven foot pipe... now back to the regs to see if that's allowed..

 

[begreen]

As soon as the flue passes through the ceiling or a wall it needs to be chimney pipe. We could use some pics and a sketch to avoid giving misinformation.

 

[bholler]

Yup, that's what they make 'em for... this is my last place.
View attachment 244854

You are not allowed to use 45s for solid fuel. 15 or 30 only. If they make 45s they are only for oil or gas

 

[Sawset]

You are not allowed to use 45s for solid fuel. 15 or 30 only. If they make 45s they are only for
oil or gas

Are they allowed in Canada?
Reread from above post:
"Selkirk Ultimate One says their 45's are listed for use/sale in Canada only."