# installing a chimney around this roof overhang?



## robertjp (Aug 9, 2010)

I need some help figuring out how to install a chimney for a new install on our cottage. We want to put a WB stove in this fall. Want to get the chimney ready for whatever stove we decide. I have this roof overhang as you can see in the pic. It is about a 12" or so overhang. the chimney can be flush to the building till you get to the overhang, then what? I know virtually nothing about woodstoves so go easy on me.Thanks in advance.

P S Is 6" double wall pipe a good choice?


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## begreen (Aug 9, 2010)

Why put the flue on the exterior? It's already going to be a short chimney. An exterior flue with one or two 90's in it is going to further reduce draft.  Looks like straight up the middle on the interior near the peak would be the best. It will probably cost less too. But even if it is not near the middle I would still try to go interior.

Download the flue installation guide from Simpson. It has some good diagrams illustrating the options. The pipe used to connect the stove is called the connector. It comes in double wall and single wall. This pipe is only used until there is a penetration of the room. From that point on it must be Class A pipe. Class A comes in double wall or in some cases triple wall. But for this application double-wall class A should be fine. 

http://www.duravent.com/docs/instruct/L150_Apr10.pdf

Without seeing the actual interior layout and ceiling details, I'd be just guessing at what is needed, but this diagram from the instructions may give you an idea if the structure is similar.


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## robertjp (Aug 9, 2010)

Cant because its a metal roof and the only ceiling we have are drop ceiling tiles, no wood or drywall.


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## begreen (Aug 9, 2010)

A metal roof is not an obstacle. There are flashing kits for this. 

I could be in error but I would think that a support box like in the illustration would just need aluminum angle irons attached to support the surrounding drop ceiling. The weight of the support box and flue pipe is supported by a flange you create on the roof by folding outward the trimmed section of the support box.


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## robertjp (Aug 9, 2010)

I would rather not involve the metal roof. It would be easier for me to go on the outside if I could figure out how to get around the overhang.


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## oldspark (Aug 10, 2010)

Would it be ugly, stupid, against the code (law) to use support brackets long enough to clear the sofit so its straight up?


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## DAKSY (Aug 10, 2010)

robertjp said:
			
		

> I would rather not involve the metal roof. It would be easier for me to go on the outside if I could figure out how to get around the overhang.



You'll just have to use 15 or 30 degree offsets. 
Once you figure out whose Class A you're going to use, the offset charts 
issued by that manufacturer will tell you how much length you'll 
need between the offset & the return...
You'll also have to make sure you meet the minimum chimney height criteria for the stove you purchase.
Like BeGreen said, any offset - including the tee at the bottom of the chimney & the 90 inside 
- unless you get a rear exit stove - will restrict the draft & you can only make up for
that restriction by increasing the overall chimney height.
If you don't mind paying for the extra footage, looking at an "unexploded scud missile", 
adding the required chimney supports & brushing thru the offsets, I'd say you're good to go!


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## robertjp (Aug 10, 2010)

Well....thanks but you sorta lost me. Im a total newbie with this stuff. Is there a pic you can direct me to to show me what a 15 or 30 offset is?

Whoose class A  ???

Our stove is rear exit, how high over the roof would I need to go approx.? This cabin is in the middle of nowhere or Id just have a dealer install it but looks like I'll have to do it.


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## oldspark (Aug 10, 2010)

As BeGreen stated there are flashing kits for the roof that look like it will be a breeze going through the metal roof, a couple of hundred bucks or so buys a nice one. Somebody posted the site a while back maybe I can find it.


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## oldspark (Aug 10, 2010)

Do a search for metal roof flashing and enjoy, maybe the way to go.


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## begreen (Aug 10, 2010)

This is for the little Scandia right? If it were me, I would not come right out of the back of the stove and exit the bldg to the exterior tee. Do that and forever that is the flue exit height you are stuck with. In the least, if that is the plan, put the stove on a raised hearth so that if you want to change the stove later on, you may have the option of lowering the hearth to accommodate the new stove's flue height. 

Avoiding a hole cut in the roof is going to cost a lot more. There are many more parts involved going exterior, especially with the offset elbows. Class A pipe is expensive. The offset alone will run about $300+ in parts. The offset table, with pictures is also covered in the Simpson installation guide mentioned earlier.

The code is: Chimneys shall extend at least three feet above the highest point where it passes through the roof of a building, and at least two feet higher than any portion of a building within ten feet.”

The stove will need at least 12' vertical rise in the chimney to draft properly. Each 90 deg turn in the smoke path is going to effectively remove about 3' of chimney height with reduced draft.


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## begreen (Aug 10, 2010)

The eave depth is not too great. Here's an alternative, notch it to clear the pipe. That will avoid the cost of the offset.

https://www.hearth.com/econtent/index.php/forums/viewthread/52119/


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## Pagey (Aug 10, 2010)

robertjp said:
			
		

> Well....thanks but you sorta lost me. Im a total newbie with this stuff. Is there a pic you can direct me to to show me what a 15 or 30 offset is?
> 
> Whoose class A  ???
> 
> Our stove is rear exit, how high over the roof would I need to go approx.? This cabin is in the middle of nowhere or Id just have a dealer install it but looks like I'll have to do it.



Here is an example of a 30 degree elbow: http://www.ventingpipe.com/metal-fa...ree-elbow-from-the-temp-guard-series/p1231055

Class A simply refers to the type of venting pipe you'll be using to vent your stove.  There are many manufacturers who make it (Simpson, Selkirk, ICC, Hart & Cooley).  It's also referred to as UL 103 HT pipe.  UL is for Underwriters Laboratories, and 103, I believe, would be the standard which the pipe is certified against.  In any event, going out the wall or up through the roof, a wood burning stove setup will involve: the stove of choice, connector pipe (or stove pipe; this is the black pipe you often see inside), a ceiling support box (square or round, depending on brand and your set up), and Class A/UL 103 HT venting pipe.

Class A will require a 2" CTC (Clearance To Combustibles).  Take a look at the notching used in the thread BeGreen linked.  I would personally go that route for appearance if nothing else.


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## 70marlin (Aug 10, 2010)

Save yourself some grief, hire the job OUT!


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## robertjp (Aug 10, 2010)

Guys,

Thanks for the good info...really. The notching idea seems like my best best as I dont like the idea of having to cut through the metal roof and then worrying about leaks. Not too mention the fact that I really dont have a ceilng other than a drop ceiling with soft tiles on it (above that is the metal roof of the cabin). As long as the notching idea wouldnt affect the structure integrity, that may be the way to go for me. I noticed in the thread you sent with the photos of braces on wood being using to support the pipe to the house, is the wood so it stays 3" away from the house? Is 3" the code or manufaturers specs? Begreen you have a really good point I never thought of. If I install this pipe before I know what stove Im gonna use, Im stuck with the height. I was gonna install the pipe and have it ready to go once we decide on a stove so it was "wood stove ready" but it sounds like I should do it all at once. The only thing Im not sure of about the notching method is the eve is wood but the metal roof should come to the edge so I would have to notch the metal roof too? What would I use to seal it so it wouldnt leak? Thanks again. 

P.S Im still not sure about using the Scandia, there seems a mixed reaction here wether its safe or not and if I could even find the oblong to round pipe I need from the back of it.


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## SolarAndWood (Aug 10, 2010)

Good luck keeping a pipe through a notch from leaking on a fairly shallow roof in Western NY.  One good heavy wet snow off Lake Erie and that seal will be done.  I have 4 chimneys through notches at our family's camp.  Well, now we have three as the snow took one of them out 2 years ago.  The remaining 3 all leak periodically and have to be repaired every couple years.  I can only imagine how rotted they are underneath.

If you don't want to go straight up through the ceiling, which is what I would do, I would consider building a chase around the pipe.  You can then put some kind of diversion uphill of the chase to protect it from ice, snow and to a lesser extent rain.


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## PitPat (Aug 10, 2010)

I had the same problem when I was installing my stove a couple of years ago.
I ended up just running an exterior flue that goes straight up the side of the house until it reaches the overhang. I then used two elbows to go out around it and up a couple of additional feet. I couldn't afford to enclose the flue at the time of the install, and decided I would just set it up and not make any additional penetrations into my roof until I could afford to enclose the entire flue properly.
It turns out, that I don't think I will ever need to.
I do have a little trouble getting a draft started when there is a high pressure system above me or if the flue gets extremely cold relative to the house, but once the fire is lit it draws great and I don't seem to get very much additional creosote buildup at the corners (I do get some, and its a little tough to pull a brush through the elbows, but all in all it works fine for me).
I still plan on insulating my flue at some point, but its gotten moved way down the list at this time.


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## mikefrommaine (Aug 10, 2010)

It seems to me through the roof would be easier and cost effective. 

You can use a rafter support kit to take the weight of the chimney and still use the ceiling trim kit in the drop ceiling so everything looks nice and is safe.

http://www.bellfiresusa.com/images/roof_support_package.jpg

It is easier than you think to go through a metal roof, and with the right flashing it will be weather tight. You don't need much more than a sawsall, utility knife  and hammer to do the job.


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## oldspark (Aug 10, 2010)

When I was looking at roof flashings for my shop I thought this one looked like the ticket, have not installed the wood burner in shop yet so cant tell yu first hand how good it is.
http://www.bestmaterials.com/detail.aspx?ID=16058


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## robertjp (Aug 10, 2010)

would it be safe running a pipe through a soft drop ceiling tile? Doesnt sound too safe too me unless there is a special  tile. Just when I get comfortable with a method, someone shoots it down. Whats a newbie to believe? I dont know which way to go now.


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## 70marlin (Aug 10, 2010)

I can’t over state it enough, go get yourself a pro! And let them do it correctly and permitted. You have a nice place keep it safe. Go do what you do make the money and just make sure the person you hire is the right person. You’ll sleep better at night and your insurance will be cheaper!


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## Jonsered (Aug 10, 2010)

oldspark said:
			
		

> When I was looking at roof flashings for my shop I thought this one looked like the ticket, have not installed the wood burner in shop yet so cant tell yu first hand how good it is.
> http://www.bestmaterials.com/detail.aspx?ID=16058



Wow that is a pretty neat unit...is this intended for metal roofs only or any roof? I think I might pick this up for my chimney where it goes through the roof (if it works for traditional tar shingle roofs).

Nate


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## oldspark (Aug 10, 2010)

Jonsered said:
			
		

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 It says it will work on any kind of roof and it has a 20 year waranty, seems like the answer for many instalations.


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## Jonsered (Aug 10, 2010)

oldspark said:
			
		

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Affordable answer at that!

Is that available in different colors? I would prefer black so it would not stick out quite as much.


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## mikefrommaine (Aug 10, 2010)

robertjp said:
			
		

> would it be safe running a pipe through a soft drop ceiling tile? Doesnt sound too safe too me unless there is a special  tile. Just when I get comfortable with a method, someone shoots it down. Whats a newbie to believe? I dont know which way to go now.



I don't see why not -- as long as the required clearances are met, though I'm no expert.  I would still use the ceiling support kit (with the roof support) so that the chimney doesn't move and everything is trimmed out. But the weight of the chimney would be hanging from the rafters.

If you are worried about the drop tiles you cold always replace the one with the chimney through it with 5/8" sheetrock.


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## mikefrommaine (Aug 10, 2010)

When you come up with your final design try contacting the customer service rep to go over your plan. I have found selkirk to be very helpful when I asked them to review my plans.


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## begreen (Aug 10, 2010)

mikefrommaine said:
			
		

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This is no different than supporting the flue with a cathedral ceiling support box. The roof supports the support box. Please read the installation instructions.


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## Pagey (Aug 10, 2010)

BeGreen said:
			
		

> This is no different than supporting the flue with a cathedral ceiling support box. The roof supports the support box. Please read the installation instructions.



That's what I was thinking.  Just use the cathedral ceiling support box and replace the tile in the drop ceiling with something that the connector pipe can pass by?  But what to use in place of the drop ceiling tile?


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## mikefrommaine (Aug 10, 2010)

I think the rafter support is less expensive than the cathedral kit, though they do the same thing.

Does the tile even need to be replaced? I don't think they are that easy to set fire even if you want to. Can't he just maintain the clearances?


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## begreen (Aug 10, 2010)

Pagey said:
			
		

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The cathedral ceiling support box should be cut so that it hangs at least 2" below the drop ceiling. Then pop rivet on some angle metal to support the ceiling tiles and cut the tiles to fit around the support box. They will rest on the ledge created by the angle metal.


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## mikefrommaine (Aug 10, 2010)

That seems like a better plan than mine -- as long as the support box is long/tall enough.


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## Pagey (Aug 10, 2010)

BeGreen said:
			
		

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Gotcha.  I wonder how far the drop ceiling is below the real ceiling, though.


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## robertjp (Aug 10, 2010)

I will take some detailed photos this weekend so you guys can see what Im up against. Thanks to all.


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## Sparkster (Aug 12, 2010)

I just used one of those red silicone flashings for installing a mast-type electrical service through a metal roof overhang. You just hand-form the aluminum flange over the roofing ridges, then lay down some butyl tape, and screw it down. Fast and easy.


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## oldspark (Aug 12, 2010)

Sparkster said:
			
		

> I just used one of those red silicone flashings for installing a mast-type electrical service through a metal roof overhang. You just hand-form the aluminum flange over the roofing ridges, then lay down some butyl tape, and screw it down. Fast and easy.


 Thanks, I think that is what I am going with on my shop wood burner.


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## humpin iron (Aug 19, 2010)

You are in way over your head and you havent even started yet, I don't mean that in a mean way, it just sounds like it from what your writing..  Go to a good stove shop, ask advice, a knowledgeable installer standing there waving his hands will explain in 20 mins what will take you 20 pages to understand here.  Nothing against the people here, but in person is far better than on a screen.  Then be thankful for the "free" advice and make your purchase of parts there.
**The problem with the red silicone boot that was shown= you will notice there is no UL listing, those boots are nice however none of them can pass a chimney fire test to get a rating, just FYI guys.
If you end up doing the job yourself I would recommend out the wall and up with a simple offset to get around the overhang, if you cut the metal roof and make a mistake it's a costly mistake, not like plywood and shingles, I know my shop has 21 chimneys through a metal roof.


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## oldspark (Aug 19, 2010)

Good info iron but there are flashings that are UL rated but did not realize that one was  not UL rated,  this one is.
http://www.discountchimneysupply.com/catalog/item/7168127/7375932.htm


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## SteveKG (Aug 19, 2010)

Notching the overhang, going through the overhang, going up and around the overhang, or going straight up indoors through the drop tiles and the roof all are fine. There will be costs associated [monetary costs] with any of those options. And each method will have its own hassle as for labor. 

Personally, I would go up through the room indoors. The ceiling and tile are no problem, there will be some labor cutting the tile to let the pipe through and maybe even relocating some tile supports. Not a big engineering project but some time involved. There are various offset [and/or insulating] devices to allow pipe through walls, ceilings, and etc. just for this purpose. You will have to support the device as the ceiling tile system will not. However, it will not have to support the pipe itself, the pipe will simply pass through it. You can make your own, just cut the hole in the tile larger than the pipe and make a nice-looking trim for it from whatever, sheet metal perhaps. 

Note that I am assuming well-insulated stovepipe. I would not want to go near the ceiling with single-wall stovepipe, and you don't either. 

If you are handy, you can do this. Take your time. I've done it on our three stoves and it is fine. We have a steel roof [standing seam]. The section of pipe with the roof attachments built in supports the entire pipe down to the stove and above the roof. I put that piece in first, and get the roof boot done so I can cover that piece of the pipe with a plastic bag and be safe from snow/rain/etc. and then take my time running the pipe down through the ceiling and to the stove. The part of the pipe above the roof is simply a matter of putting it up and securing it with guide wires or whatever support system you decide.

If you are not handy, this is not a job for you. You'll either end up with a leaking roof, an unstable stovepipe, or a dangerous set-up. You want to be able to go to sleep at night and not fear a fire from your project.


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## tiber (Aug 19, 2010)

I'm going to be contrary to the advice here for one condition - if it's a metal roof with the "wavy" (corrugated)metal, go around it. It's impossibly hard to get any sort of flashing to seal to it, and you'll likely collect water in the roof around the flashing even if you do it properly and get it to seal. 

When I was pricing out chimney stuff I did the math and it was cheaper for me to go out the wall and up. You can chase it in (or not) and more on the point if I get fed up with it or the next owner of the house doesn't like it, it's trivial to remove the hole in the wall versus having to patch the ceiling and roof. Again, consider how much fun it's going to be to patch the corrugation. :\


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## robertjp (Aug 20, 2010)

I guess there is no "right" way. You all bring up great points so it just confuses a newbie like me. Guess I'll flip a coin.


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