The wood stove chimney

It started out with a kiss; how did it end up like this? ~ The Killers, Mr. Brightside

The wood burning stove sits at the end of the kitchen island, and this means it is under the kitchen ceiling so the chimney will have to go through that ceiling before penetrating the roof of the cabin. Fire code says you can use single wall pipe straight out of the stove until you penetrate a ceiling / wall / roof. At that point, you must switch over one of two types of pipe:

  • Double wall pipe, which has a 6″ clearance requirement on all sides; or,
  • Chimney pipe, which has a 2″ clearance requirement on all sides.

Cost-wise, a double wall pipe seems like the answer, but that clearance requirement means that the hole through the floor would have to be 8″ (pipe) + 6″ (one side) + 6″ (other side) = 20″, and my ceiling joists only give me 19-1/2″ of space between the joists. Chimney pipe it is then.

But Chimney pipe is extremely pricey: the best I could find it for was $4.00 an inch! And I have about 16′ of space inside the house to cover. I coughed up the money and bought 5 sections of 4′ long pipe, plus an extra 3′, just in case I couldn’t meet the height requirement on the roof.

Fire Codes

After reading through pages and pages of fire code from the county, city, state, and fire jurisdiction requirements, we felt like we were ready to get ideas for what we could do within fire code restrictions. We began to be surprised at all the fire code violations we saw on Pinterest and image search engines – a lot of those pretty pictures online are actually violating clearances!

Quick and dirty drawing of the initial stove pipe plan. Note: not the final plan.

The most important thing to remember with fire codes is clearances. The next thing to think about is penetrations. Finally, code says you can’t mix the same products from two manufacturers – you can’t buy Duravent chimney pipe and try to get it to work with Selkirk chimney pipe, for example.

And no one will tell you what to buy for your situation, unless you pay them. My list of accessories is below. The photo above is almost correct – the only thing wrong with it is the cathedral ceiling support box, which I found out I didn’t need according to a lady at Selkirk. She said the ceiling support box on the first floor is sufficient to hold up to 50′ of chimney pipe. Or you can hang the chimney pipe from the roof and use a cathedral support box – but you don’t need both supports because when the pipe heats up, it expands a bit, and you don’t want it restricted between two supports.

I want to reiterate: I noted in an earlier post that while planning the chimney, I called my building inspector and had him come out and take a look at my drawing and where I wanted to put the stove. If you are planning something like this – no matter what the national / state / local codes say, your inspector has the final word. Mine said he appreciated me trying to follow code and after making a few suggestions, I guess he felt comfortable with my plan and joked, “do whatever you are going to do – it sounds like you know more about the code than I do!” I doubt all inspectors will come across this way, but it seems like he likes what we’ve done so far.

Finding info and deals on the chimney pipe and accessories

I looked all over the internet for good deals. They are hard to find on chimney pipe. I thought if you buy a package deal – like a “roof installation kit”, it would be cheaper, too. Nope. One thing to note is you can mix single wall pipe from one manufacturer with chimney pipe from another. They won’t tell you that, but it is in the code. One thing you can’t do, however, is mix in roof flashing made by Duravent with Chimney pipe made by Selkirk.

The other problem was that folks are getting “ancy” in the northeast this year over heating fuel. I guess everyone remembers what happened earlier this year in Texas when the power went out – no one had alternatives to heating their homes. I had a big, long, raving rant about prepping all typed out here, but decided not to include it – I’m going to make my point with just two statements:

Two is one, and one is none” and “Always have a backup plan.

I checked out hearth.com and made a post about what I wanted to do – figuring I would find some experts over there, but got told, “no one is going to give you a parts list”. Why not? I gave them exact dimensions and lots of photos – seems like it would be easy for an expert. I guess I was on my own. Or I could hire “a professional”. 🙂

I finally found a website with answers: https://inspectapedia.com/index.php. And pictures! I made notes on what the fire code required, verified them with my city code, then set about on ebay finding deals. I decided to work from the roof down because I know exactly where it will penetrate on a North-South line.

Purchase list

(See, Hearth.com? I made a parts list….) Note: my stove has a 6″ flue. I found this by wrapping a tape measure around it and finding that it was 18″+change. Divided by 3.14 (Pi) gives your your diameter – 6″. This is a very common flue size for a wood stove. 8″ is another one. For pellet stoves, it looks like it is about 3″. But pellet stoves have very different requirements for venting, and I didn’t look into that too much, since I have a wood stove. And since I brought up pellet stoves – I don’t like them for one reason: you have to buy pellets. I mean, you can’t make pellets. And what if all the sudden you can’t buy pellets? Plus, a lot of pellet stoves are fed by way of an electric motor. This is great to keep the heat consistent, but I saw pellet owners asking about solar powered electric motors for when the power goes out. What if the power goes out at night? See how complicated this can get? With my wood stove, I just need wood. Anyway, the chimney parts list, from top to bottom:

  • chimney cap (generic is fine)
  • storm collar (make sure it fits with the chimney pipe brand)
  • roof flashing (must match the chimney pipe brand)
  • Class A chimney pipe
  • ceiling support box (must match chimney pipe brand)
  • double wall / chimney pipe to single wall adapter
  • adjustable slip collar (makes it so you don’t have to get the single wall pipe exactly the right length – also good if you ever want to disconnect the stove (like to replace it)
  • single wall pipe
  • damper
  • round to oval flue adapter
  • stove (duh. But I thought I’d throw it in so you’d know that’s the end of the list)

Installation (done from bottom up)

Everything but the stove is in this picture for the first floor pipe.

I planned the installation from the top down, but did the actual installation from the bottom up. So I’ll describe the installation from the bottom up. We positioned the stove exactly where we wanted it, then drew a chalk outline on the floor. We installed the backerboard, making sure we would meet clearance requirements for the front, sides, and back of the stove. Then we built the hearth (see this post). Part of building the hearth was drilling a small pilot hole through the 2nd floor and extending the plumb bob all the way from the roof to the wood stove flue location to ensure the hearth would be located in the correct location below the chimney pipe – and part of getting the roof location correct was making sure I didn’t go through any rafters or ribs on the roof. It was a lot to think about when planning the location.

Installing the first floor ceiling support box ended up being very difficult. For one thing, most homes have 2×12’s as the ceiling joists, spaced 16″ apart on centers. For these installations, I assume framing it in for a ceiling support box means just adding 2x material all around to reach the 12″ opening needed for the ceiling support box. Our difficulty was that we have rough cut 4×12’s, spaced 24″ apart on centers. My area to frame in was 19-1/2″. 2x framing material just wasn’t thick enough. And I didn’t want to just double everything up until it fit – that would look tacky. So I had to look through my scrap pile to find thick enough “lumber” – a 3-5/8″ thick slab – to frame in the support box:

framed in ceiling support box

This is the box that supports the single wall pipe, houses the adapter that switches the pipe from single wall to Chimney pipe as it passes through a ceiling, and then supports the heavy chimney pipe all the way through the roof.

Looking down to the brick hearth from the 2nd floor. The metal ceiling support box is in view.

Chimney pipe

Temporarily installed chimney pipe just to make sure it will penetrate the roof in the right spot.

Painting the chimney black. Outside of this pipe gets up around 200 F if the fire is hot enough. Mine barely reached 120 – I could touch it with no problems.

Framing the roof

Roof penetration

I waited until Christmas Eve when the weather was nice so I could get the whole thing done in one shot. The plan was to cut the hole in the roof, get the flashing installed under the shingles and seal it, push the chimney pipe up through the hole in the roof, install the chimney cap and storm collar, and finally the bracing.

On the day I picked, I started inside with the framed in box by finding the center of the box and drilling a hole up through the ceiling with my 24″ bit. Then up on the roof, I used the sawzall to cut through the shingles and the decking for them, then cut out the insulation, and finally the 2×6 T&G decking. I made sure I had a two inch clearance on all sides of the hole to make room for the chimney pipe.

Once the hole was made, I cleaned out all the debris, and test fit the roof flashing. Then I installed the flashing following the instructions, and locked my chimney pipe together and shoved it in the hole.

Code says you must have at least 3′ of chimney pipe sticking out of the roof. But you must also be 2′ higher than anything on the roof within 10′ of the chimney. The peak of the roof is 8′ away, so I have to have a 6′ chimney (8 feet from the peak of the roof means the peak of my 6/12 roof is 4′ higher than the hole I cut, so 4′ + 2′ = 6′).

Support bracket

I finished off the roof portion with a home made support bracket. You can buy a support bracket for about $100. Or….you can make one for about $20. I’ll bet dollars to donuts the homemade one is stronger. I followed this guy’s idea almost exactly:

Next steps

With the stove pipe in place, the brick hearth completed, and the stove restored, we decided to fire this stove up and see how it worked! And it worked beautifully! I checked carefully for any smoke and also checked the chimney for leaks – nothing. The stove had a strong draft which kept the smoke moving up and out of the house, even with the door open to stoke the fire.

The longer the chimney, the better the draft. Ours sucks impressively!

The whole point of getting the stove installed was to heat the place so we could keep working throughout the winter. Not as cold as you folks up North, but still cold enough that a hot fire is welcome. Now we can work on stairs, electrical, plumbing, finish work, and more chinking!

A note on the temperatures inside the cabin: The cabin is fully chinked and insulated on the outside. I’m holding off chinking the inside until we get the electrical run in – some of the wiring will run in between the logs. The only real purpose of chink is to hold the insulation in place. Some folks think the chink is for keeping the logs dry, but that’s what the roof is for. The floor is not insulated, and neither are the gables at this point, but wind doesn’t blow through the place. During the summer, I noticed the cabin stayed at whatever the low temperature was for the night before, so that was welcome. But the same is true in the winter – so it is like an icebox when we go out there in the afternoons – always 10-20 degrees cooler than the outside temperatures. I’ve tried opening all the windows and doors to “heat the place up”, but I guess the logs are moderating the temperature very well because it refuses to warm up that way. While up on the roof cutting through the 8″ of foam insulation, I noticed near the shingle side, the insulation was warm. But as I cut lower and lower into it, it got colder and colder. Near the bottom (on top of the T&G decking), the insulation was downright cold. So the roof insulation is doing its job – moderating the temperature inside the house. It also means wood stove is necessary to continue working, otherwise, we’re going to freeze inside the place. January through early March are the coldest months of the year around here, so getting this stove as a Christmas present is a comforting accomplishment.

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