If a person makes sure their chimney is at least 2 foot higher then any part of the roof 10ft away, but that still doesnt rasie the chimney above the roof peak, should the draft still be adequate enough in all situations { including windy days } to run the woodstove and not encounter any smoke coming into the home ? ?
Question about the 2-10 rule and roof peak
- Thread starter rumme
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
dougand3
Minister of Fire
I can't speak from experience but you sound within guidelines (+ chimney should extend 3 ft above the roof exit - be it asphalt, metal, slate, etc). Someone with your specs will chime in.
At least 3 feet higher than where it penetrates the roof (measured on the high side), then, if necessary, extending up so that it's at least 2 feet higher than any part of the structure within 10 feet horizontally. If the chimney penetrates the roof far enough down the slope from the ridge, and the pitch is such that all the above requirements are met, there's no need to worry that the top of the chimney is below the ridge. Make sense? If the chimney's more than 10 feet from the ridge horizontally, and the roof pitch is relatively mild, or it's just a big roof, then it could well be that the chimney needn't extend vertically above or even as high as the ridge. Rick
EDIT: This has to do only with the requirements for the chimney above the structure. Draft will be predominantly affected by the total height of the chimney. Your woodstove manual should give some guidance in that regard. In some cases, a chimney may need to be well in excess of the minimums for good system performance. Depends on how the house is put together and the layout of the installation.
EDIT: This has to do only with the requirements for the chimney above the structure. Draft will be predominantly affected by the total height of the chimney. Your woodstove manual should give some guidance in that regard. In some cases, a chimney may need to be well in excess of the minimums for good system performance. Depends on how the house is put together and the layout of the installation.
thanks for replies...
my chimney goes out my wall then up the outside brick wall....
I hung a 16 ft tall chimney...with 9 ft above where my gutters tie into the roof and the other 7 ft below that point, which is then fastened to my brick outside wall for extra stability. But this only got me to have the chimney top even with the part of the roof 10 ft away. The stove works great, as long as the wind isnt to bad.....once the wind kicks up, then smoke enters my house . Im gonna weld another 3f section onto what I alread have, this will get me 3 ft above the 10 ft horizontal roof measurment, but I will still be about 5-6 ft below my roof peak .
my chimney goes out my wall then up the outside brick wall....
I hung a 16 ft tall chimney...with 9 ft above where my gutters tie into the roof and the other 7 ft below that point, which is then fastened to my brick outside wall for extra stability. But this only got me to have the chimney top even with the part of the roof 10 ft away. The stove works great, as long as the wind isnt to bad.....once the wind kicks up, then smoke enters my house . Im gonna weld another 3f section onto what I alread have, this will get me 3 ft above the 10 ft horizontal roof measurment, but I will still be about 5-6 ft below my roof peak .
stats :
napolean 1900p
single wall black stove pipe inside = 2 ft vertical - 90 degree elbow - 2 ft thru wall into wall thimble then into a 8x8 steel square chinmney that goes up 15 ft and has 1ft below outside connection with trap door for cleaning { 16 ft total length of chimney } ......the 8x8 square chimney is 3/16" thick single wall and non insulated and there isnt any brick work around it...just the steel chinmney itself.
napolean 1900p
single wall black stove pipe inside = 2 ft vertical - 90 degree elbow - 2 ft thru wall into wall thimble then into a 8x8 steel square chinmney that goes up 15 ft and has 1ft below outside connection with trap door for cleaning { 16 ft total length of chimney } ......the 8x8 square chimney is 3/16" thick single wall and non insulated and there isnt any brick work around it...just the steel chinmney itself.
Interesting. Part of your draft problem might be that you're dumping a 6" diameter flue (~28 in^2 cross-sectional area) into an 8"x8" chimney (64 in^2 cross-sectional area). More than twice the area for gas flow, coupled with the fact that it's exterior and uninsulated makes for a less than optimal configuration. I really doubt that proximity to the ridge has anything to do with it. More chimney height should help, I'd think. You have any sort of a chimney cap on this thing? Rick
Backwoods Savage
Minister of Fire
Yes....I do have a chimney cap on top...
so, if I add another section of 6x6 square chimney to my 8x8 chimney, which will raise it to the 2-10 rule, I should get better draft and help alleviate some of the smoke problems during windy days ?
so, if I add another section of 6x6 square chimney to my 8x8 chimney, which will raise it to the 2-10 rule, I should get better draft and help alleviate some of the smoke problems during windy days ?
I'm far from expert, but if I read your description correctly, the exterior chimney is 3/16" steel with *NO* insulation or surround whatever.
If that's the case, I'd think you'd be inviting draft problems... including the backpuffing on windy days that you mention... though the latter _might_ be cured with a draft inducing chimney cap. I'd think it would be very difficult to maintain temperatures sufficient to maintain an even draft through the course of a burn with an entirely uninsulated metal chimney.
Two cents.
Peter B.
-----
If that's the case, I'd think you'd be inviting draft problems... including the backpuffing on windy days that you mention... though the latter _might_ be cured with a draft inducing chimney cap. I'd think it would be very difficult to maintain temperatures sufficient to maintain an even draft through the course of a burn with an entirely uninsulated metal chimney.
Two cents.
Peter B.
-----
Peter B. said:
yes, you are correct...no insulating at all around the chimney....so I know most of my chimney is not getting heated up via the exhaust of the woodstove
rumme said:
Well, again, I should defer to those here who know (far) more about chimneys and such than I.
But I'm inclined to think you'll only continue to have problems with your current setup.
I don't know how best to remediate it, but I expect others will come along and make suggestions.
Peter B.
-----
KeithO
Minister of Fire
What is the point of the 8x8 uninsulated chimney ? Did you happen to have the material lying around ? Remember that single wall clearance to combustibles is 18". Hard to imagine that you have that much clearance in your install.
Perhaps you have no code requirements where you live, but you are still inviting creosote buildup, which if ignited would potentially exceed the melting point of mild steel and through radiation, set fire to the side of the house. Class A Chimneys are insulated for 3 reasons: 1) to prevent condensation of moisture and creosote, thereby actively reducing the risk of a chimney fire, 2) Retain the heat in the flue gasses to create an adequate level of draft, 3) If the worst happens and a chimney fire is ignited, to safely contain the heat to prevent ignition of combustibles within 2" of the chimney.
Your stack will not fulfill any of the 3 above requirements. Better to start over. 6" class A costs $20/ft at Menards. Better than a burnt down house and maybe some dead family members.
Perhaps you have no code requirements where you live, but you are still inviting creosote buildup, which if ignited would potentially exceed the melting point of mild steel and through radiation, set fire to the side of the house. Class A Chimneys are insulated for 3 reasons: 1) to prevent condensation of moisture and creosote, thereby actively reducing the risk of a chimney fire, 2) Retain the heat in the flue gasses to create an adequate level of draft, 3) If the worst happens and a chimney fire is ignited, to safely contain the heat to prevent ignition of combustibles within 2" of the chimney.
Your stack will not fulfill any of the 3 above requirements. Better to start over. 6" class A costs $20/ft at Menards. Better than a burnt down house and maybe some dead family members.
where I live, it seems many people use a thick walled steel chimney purchased from our local metal dealer. The 6" class A chimney you speak of at Menards doesnt rust out to quickly..does it ?
we dont have a mernards near me and I would need 20 ft of it .
we dont have a mernards near me and I would need 20 ft of it .
oh....as far as combustiblles being to close to my chimney...my house is brick..and my roof is metal....so im allright in that dept. but I AM 20 " away from my brick .
well let me ask this..
if I add another 4ft of chimney , it would most certainly not hurt the draft..correct ? and probably help since it would then be following the 2-10 rule..
the smoke problem only happens on windy days of about 12 mph or more....anyhting less then that, and it works perfect
if I add another 4ft of chimney , it would most certainly not hurt the draft..correct ? and probably help since it would then be following the 2-10 rule..
the smoke problem only happens on windy days of about 12 mph or more....anyhting less then that, and it works perfect
also, I can easily check or cleanout any creostoe problems, since I installed a cleanout door at the bottom of my chimney. So far I havent had any noticeable buildup/ problems in that dept.
rumme:
You appear to be asking this group to give our blessing and reassurance that your setup is / will be usable even though it may not adhere to any known code.
I don't think that's going to happen.
My opinion is that aspects of your install are (almost literally) bulletproof. I don't think your 8x8 mild steel chimney will melt down readily in a chimney fire... but I'm pretty sure it will never perform the way you hope... and your new stove is not likely to work to best advantage either.
To answer one question in particular, I installed a Class A (stainless, double wall) chimney (inside/outside) most of twenty years ago... and I expect to get the rest of my lifetime (maybe another ten, twenty years) out of it. It has not rusted or discolored in all that time.
Once again - 'for what it's worth'.
Peter B.
-----
You appear to be asking this group to give our blessing and reassurance that your setup is / will be usable even though it may not adhere to any known code.
I don't think that's going to happen.
My opinion is that aspects of your install are (almost literally) bulletproof. I don't think your 8x8 mild steel chimney will melt down readily in a chimney fire... but I'm pretty sure it will never perform the way you hope... and your new stove is not likely to work to best advantage either.
To answer one question in particular, I installed a Class A (stainless, double wall) chimney (inside/outside) most of twenty years ago... and I expect to get the rest of my lifetime (maybe another ten, twenty years) out of it. It has not rusted or discolored in all that time.
Once again - 'for what it's worth'.
Peter B.
-----
no, im not asking for anyone blessings..im asking for advice/ There is a difference. The question is in my very first post.
North of 60
Minister of Fire
To answer your question in your first post, It is unknown as your install 1) Is not of normal practice. 2) I does not at all follow the install procedure your manufacture has suggested. EDIT: (The rest of all the attempts you may now make to remove doubt about your problem without starting from scratch would be just band aid solutions.) = My advise.
Good luck. N of 60
Good luck. N of 60
KeithO
Minister of Fire
Have you checked the top of the chimney for creosote ? Is there any wood supporting the tin roof ? Have you checked to see how warm the gas is at the top of the stack ? If water will not vaporize the moment it touches the chimney at any point, you will be getting condensation inside. Creosote will condense out at a temperature higher than the boiling point of water.
Your climate is warmer than mine, but I get creosote forming in the last 2 ft of my chimney which is only 16ft from ceiling to rain cap with another ~9ft of single wall below. That is with 1" packed insulation and about 4ft above the roof line. Now I don't get much, perhaps 1/8" per season, but I shudder to think what I would get with a 20ft run of fully exposed single wall pipe.
The kind of thing you are describing is exactly what led to huge insurance losses during the 70's energy crisis. That in turn led to the current code requirements to prevent more of the same from happening again. My home is worth more than $400 worth of "insurance" and the fact is that an insulated chimney will draft better and not back draft into the house when the fire cools. If you have a smoke dragon connected to the horror chimney, you can really get the chimney back drafting in the house with a low fire and bringing in CO to boot. Class A pipe is built to withstand 2 firings at 2100F for 10 minutes each. I would not like to watch that going on with a single wall mild steel pipe. If the chimney is able to draw in air through your clean out in a chimney fire, it is possible to actually combust steel if you get it hot enough. Stainless steel is a lot more temperature resistant.
Outside chimneys are bad enough (even with insulated pipe) that they are considered a typical American phenomenon, brought on by contractor / speculator cookie cutter mentality, but an uninsulated outside single wall chimney is the stuff of hillbilly legend. The only thing missing is using a window for the pass through.
Your climate is warmer than mine, but I get creosote forming in the last 2 ft of my chimney which is only 16ft from ceiling to rain cap with another ~9ft of single wall below. That is with 1" packed insulation and about 4ft above the roof line. Now I don't get much, perhaps 1/8" per season, but I shudder to think what I would get with a 20ft run of fully exposed single wall pipe.
The kind of thing you are describing is exactly what led to huge insurance losses during the 70's energy crisis. That in turn led to the current code requirements to prevent more of the same from happening again. My home is worth more than $400 worth of "insurance" and the fact is that an insulated chimney will draft better and not back draft into the house when the fire cools. If you have a smoke dragon connected to the horror chimney, you can really get the chimney back drafting in the house with a low fire and bringing in CO to boot. Class A pipe is built to withstand 2 firings at 2100F for 10 minutes each. I would not like to watch that going on with a single wall mild steel pipe. If the chimney is able to draw in air through your clean out in a chimney fire, it is possible to actually combust steel if you get it hot enough. Stainless steel is a lot more temperature resistant.
Outside chimneys are bad enough (even with insulated pipe) that they are considered a typical American phenomenon, brought on by contractor / speculator cookie cutter mentality, but an uninsulated outside single wall chimney is the stuff of hillbilly legend. The only thing missing is using a window for the pass through.
I'm far from an expert - but a little more experimental than some. I think a chimney like yours would perform better with a smaller diameter pipe. Keep the gases moving faster and staying hotter. Maybe you could fit a smaller pipe inside your 8 x 8 - not as good as an insulated chimney but better than single wall. The higher flue temps should give less back pressure - I think. Definitely less creosote.
That said - its not my house. I'm sure of all the houses that burn down from wood burning appliances some are built to code, the odds might be against you though.
That said - its not my house. I'm sure of all the houses that burn down from wood burning appliances some are built to code, the odds might be against you though.
I'm with Chunkyal - I'd vote for dropping a 6X6 or 6" round interior layer - definitely thinner metal than 3/16 - for an interior chimney.
8" square = 64" area
8" round = 50.3" area
6" square = 36" area
6" round = 28.3" area
You can see how the 8" square chimney will have such a larger area, and diffuse the draft, that you might have probs. But I'm far from an engineer...
I'd suggest you drop 6" round pipe in there. Maybe could even just by double-wall stove pipe and drip it down, and end up with a sort-of triple-wall chimney; though it would still not be a Class A it would sure help with insulation of the exterior run up the house and probably solve some of your problem. What do you have supporting the base with all that weight?
8" square = 64" area
8" round = 50.3" area
6" square = 36" area
6" round = 28.3" area
You can see how the 8" square chimney will have such a larger area, and diffuse the draft, that you might have probs. But I'm far from an engineer...
I'd suggest you drop 6" round pipe in there. Maybe could even just by double-wall stove pipe and drip it down, and end up with a sort-of triple-wall chimney; though it would still not be a Class A it would sure help with insulation of the exterior run up the house and probably solve some of your problem. What do you have supporting the base with all that weight?
the chimney weighs about 400 lbs and is 16 ft tall..
9ft of it extends above my gutter that meets my roof
the other 7 ft is below the roof line and I welded 2 pieces of square metal tubign to that, which runs down to the ground to a piece of flat plate square metal and then a concrete form is over that.
the chimney is fastened to my outside brick with steel angle iron.
I fully recongizne that not having the chimney insulated, wil cause condensation problems, but I do not think this is causing my smoke problems becuase I only experience smoke problems in the house, on windy days .
example :
the stove has performed flawlessly on nights where it is 20 degres...as long as the wind isnt gusting , but last nite, I had it running and it was only about 40 degrees out, and the wind started kicking up, and once again, the smoke came into my house and I had to shut it down.....
this seems to imply , my lack of draft is not due to cold weather and lack of chinney insulation..but perhaps the wind and the fact that my chimney top is only even with my section of roof that is 10 ft away.....
does it make sense that if I add another 2-3 ft section of chimney at the top, whcih would then make it comp,ly with the 2-10 rule , this should solve the smoke problems during windy days ?
If I was experiencing smoke problems, due only to a uninsulated chimney, then I would expect to see those smoke problems occur all the time..not just on the windy days.
does this not make sense ?
9ft of it extends above my gutter that meets my roof
the other 7 ft is below the roof line and I welded 2 pieces of square metal tubign to that, which runs down to the ground to a piece of flat plate square metal and then a concrete form is over that.
the chimney is fastened to my outside brick with steel angle iron.
I fully recongizne that not having the chimney insulated, wil cause condensation problems, but I do not think this is causing my smoke problems becuase I only experience smoke problems in the house, on windy days .
example :
the stove has performed flawlessly on nights where it is 20 degres...as long as the wind isnt gusting , but last nite, I had it running and it was only about 40 degrees out, and the wind started kicking up, and once again, the smoke came into my house and I had to shut it down.....
this seems to imply , my lack of draft is not due to cold weather and lack of chinney insulation..but perhaps the wind and the fact that my chimney top is only even with my section of roof that is 10 ft away.....
does it make sense that if I add another 2-3 ft section of chimney at the top, whcih would then make it comp,ly with the 2-10 rule , this should solve the smoke problems during windy days ?
If I was experiencing smoke problems, due only to a uninsulated chimney, then I would expect to see those smoke problems occur all the time..not just on the windy days.
does this not make sense ?
- Status
Similar threads
