Can anyone answer a chimney/woodstove venting question?

[Snowdog]

I am asking on behalf of a friend (seriously) who plans to install his new woodstove and install an unorthodox exhaust vent rather than spend the time/money on building a proper chimney.

Instead of building a chimney that vents directly up along side the house as most do, he plans to have a pipe that upon exiting the wall, will angle up approximately 45 degrees for a length of 10 feet and then abruptly terminate with some method of keeping out the rain.  Though I don't know much about such things, I told him this that is probably not only against code/regulations, but also unsafe. 

Could anyone tell me why such a silly idea is not safe and why just about all chimneys seem to vent 90 degrees towards and beyond the roof.  I'm quite sure it has something to do with keeping the house from burning down. However, if I can present him with a few examples precisely why this is unsafe, I can probably spare him from making this obvious mistake. 

Thanks in advance!

[cassandra and sara's daddy]

will the top of chimney be above ridgeline of house?  if not it will likely not draw well (particularly if the wind is blowing onto that side of the house)  he could do a powervent but those are their own nightmare

[Snowdog]

From my understanding, it will not be above the ridgeline.  He said that the roof is about 25+ feet from where the flue exits.  He plans on only a 10' extention beyond that, so I believe it will end up being far lower than the house.  He contends that he's only concerned about getting the "smoke away from the house".  I believe the process is far more complex than that, but am myself unfamiliar with the whole processs.

[cassandra and sara's daddy]

its likely it won't draw the smoke well. 10 foot of rise it might but i wouldn't bet on it

[stevelyn]

There's been different terms used for the type of engineering he's putting into his idea. He's just asking for problems and a burned down house at the worst. From the way you describe it, he's going to have 10' of pipe dangling out at 45* and not anchored securely with no mention of the type of flue he's going to use.

Nothing wrong with venting 90* out a wall and going up it's actually the easiest way to install a chimney in a house otherwise not built with it in the plans and you don't have to cut through the roof and ceiling to install it.

He needs to take the savings he going to get in heating costs from burning wood and spend it on a bulletproof chimmney and installation such as either a Metalbestos or Excel and install it right so that it vents at least 3' above the roof ridgeline. Four feet is even better.

I would also suggest using double-walled pipe as it will keep the flue and internal pipe temperature higher even with the fire banked down which will help slow down or even stop creosote build up. I like Excel and just installed new pipe at my Fairbanks house. It's has a stainless inner pipe and will handle a flue fire. The old one was double walled too but has an insulating barrier which makes it heavier than necessary. Excel chimmneys are rated at 1200* for 30 minutes and can withstand multiple flue fires without damage. Metalbestos has can only withstand a 10 minute fire and will likely have to be replaced afterward. Of course there is distinctive cost difference between the two.

[RoadKingLarry]

Please keep us updated 'cause from the sounds of it this ain't gonna end well.

[Waitone]

I'm pretty sure local codes will have a say in what can be done.

[vaskidmark]

Whatever you do, do not hold his beer!

You will want both hands free to use when videoing his chimmney fire.  Try to get audio too - the sound of a good chimmney fire is awesome.

stay safe.

[Jim147]

Poor draft, a smoky house, a hard to start fire, the chance to kill yourself. Not the best install idea I've seen.

jim

[Hawkmoon]

What he is proposing is against the building code anywhere in the U.S. that has a building code -- which at this point I think includes every state, city and town in the country. Aside from being a code violation (which automatically makes it legally unsafe, because the building code is construed in law as the minimum standard for safety), preceding posts pointing out that it won't "draw" are spot on. He is asking for trouble. The short, angled flue won't pull smoke out of the stove, and the stove will have a lousy draft. The smoke in the chimney won't rise quickly, plus the angle will increase surface contact, so if the wood he burns isn't VERY well seasoned he will greatly increase the accumulation of creosote ... and thereby greatly increase the probability of burning hiw house down.

BTW - Installing a wood stove requires a building permit. If he does it without a permit and the result is a fire, he should expect that his insurance company WILL check the building department records, and when they find out his stove was installed in violation of code and without permit or inspection ... they will politely (or not) decline to pay. Yes, I am a building inspector, and yes we have had attorneys ask to see the permit and inspection record of certain properties. These are public records ... we have to show them when asked.

[Harold Tuttle]

in soviet engineered russia, flue kills you

[Grandpa Shooter]

What he is proposing is against the building code anywhere in the U.S. that has a building code -- which at this point I think includes every state, city and town in the country. Aside from being a code violation (which automatically makes it legally unsafe, because the building code is construed in law as the minimum standard for safety), preceding posts pointing out that it won't "draw" are spot on. He is asking for trouble. The short, angled flue won't pull smoke out of the stove, and the stove will have a lousy draft. The smoke in the chimney won't rise quickly, plus the angle will increase surface contact, so if the wood he burns isn't VERY well seasoned he will greatly increase the accumulation of creosote ... and thereby greatly increase the probability of burning hiw house down.

BTW - Installing a wood stove requires a building permit. If he does it without a permit and the result is a fire, he should expect that his insurance company WILL check the building department records, and when they find out his stove was installed in violation of code and without permit or inspection ... they will politely (or not) decline to pay. Yes, I am a building inspector, and yes we have had attorneys ask to see the permit and inspection record of certain properties. These are public records ... we have to show them when asked.

There are many rural areas which have no codes.  It's whatever you decide to do.  No permit for construction, no inspections needed.  However, I have found that many companies automatically meet the standards for the metropolitan areas and will not sell anything less to folks in rural areas.  A do it yourself carport is one I have run across recently.

[280plus]

If he wants to get the smoke away from the house he needs to go up not out. We just did one here.

All from the 2000 International Mechanical Code

"vents shall terminate not less than 5 ' in vertical height above the highest appliance connected in flue collar."

Must terminate 2" above a flat roof roof  and "not less than 2' higher than any portion of the roof within 10'." So for a peaked roof you measure ten feet out from the chimney to the roof horizontally and wherever that line 10' away comes out on the roof you must be at least 2' higher than that. 

 Given anything not perfectly vertical is considered a "chimney connector":

 "Length-The maximum horizontal length of a single wall connector shall be 75 percent of the height of the chimney or vent." It says nothing about multiple wall vents and length.

So his vertical height must be 25% MORE than his runout. Technically, I think it's legal to do what he wants to do but I have to agree with Hawk's assesment of the creosote building up more on the top of the angled run rather than being distributed more evenly up a vertical run.

H'es also going to find supporting that thing to be interesting.

[sanglant]

try to go straight up for the first few feet at the woodstove, the closer to flat the more crap will build up in the pipe. there are 5 or 6 different setups to stop/reduce blow back, talk to other people in the area to find out what works there. seems there's one that works right in each town.

http://cabin.foxlore.net/cabin/stove.shtml

if it's through a closet keep the clothes etc. in the closet in bags/boxes there's a build up of soot over the decades.

oh and there's the closed fireplace setups that have the exhaust going through a 2-3inch pipe in the middle of a bigger pipe used for fresh air intake.
direct vent fireplace

[Scout26]

Also, he needs to calculate the size of the box so that the chimney is large enough to create enough  draw once he gets it above the roof line.  Having a pipe too small will only force the smoke into the house.   Making it hard for you to hold the camera steady when laughing....


http://chimneysweeponline.com/hodraft.htm

[280plus]

Coincidentally enough I JUST saw (like between posts here) a thing on one of the MSM news channels about neglected and/or DIY chimneys, burning your house down and dying. An omen maybe? 

 
 

[Hawkmoon]

Must terminate 2" above a flat roof roof  and "not less than 2' higher than any portion of the roof within 10'." So for a peaked roof you measure ten feet out from the chimney to the roof horizontally and wherever that line 10' away comes out on the roof you must be at least 2' higher than that.

Actually, the chimney/flue has to extend a minimum of 3 feet above the point where it penetrates the roof surface, AND at least 2 feet higher than any part of the roof within 10 feet of the chimney.





If it doesn't penetrate the roof but runs exterior up the side of the structure, it still has to satisfy the 2 feet above any point within 10 feet requirement in order to alleviate down/back drafts.

[280plus]

Actually, the chimney/flue has to extend a minimum of 3 feet above the point where it penetrates the roof surface, AND at least 2 feet higher than any part of the roof within 10 feet of the chimney.





If it doesn't penetrate the roof but runs exterior up the side of the structure, it still has to satisfy the 2 feet above any point within 10 feet requirement in order to alleviate down/back drafts.

Not to be a differer but I'm reading "Shall terminate not less than 2 feet above the highest point of the roof penetration." This is IMC 2000 however. Could it have changed?

But yes, the one we did was out the sil and up the outside of the house. Steep roof, we had to go 11' above the top of the penetration to get our 2'.

Meanwhile, don't worry, I have "chimney girl" for that stuff. She gets it right. 

Good to know though, I'll just make stuff a little bit taller from now on.

[stevelyn]

oh and there's the closed fireplace setups that have the exhaust going through a 2-3inch pipe in the middle of a bigger pipe used for fresh air intake

Toyostoves and Monitors are built that way, but they are forced draft/exhaust systems.

[Boomhauer]

Let's put it this way- my father, a brilliant man and very skilled builder (concrete, carpentry, bricklaying, whatever) built the house we live in. Everything from the foundation to the roof. EXCEPT THE CHIMNEY. He hired a skilled brickmason to build a chimney that connects the basement and first level fireplaces.

Venting and chimneys are one of those things that it just pays to do it right and that includes having someone who really, really knows what they are doing and has lots of experience do it, not jury rigging crap.

[cassandra and sara's daddy]

never have met your dad  but what you described would vouchsafe his wisdom

[Hawkmoon]

Not to be a differer but I'm reading "Shall terminate not less than 2 feet above the highest point of the roof penetration." This is IMC 2000 however. Could it have changed?

Most likely. There were a LOT of typographical and technical errors in the 2000 International codes, which is why very few states ever adopted them. Most states waited for the 2003 editions, which had most (not all) of the screw-ups somewhat fixed.

[RaspberrySurprise]

Wouldn't having all that smoke blowing into the wall of his house leave some pretty nasty soot marks as well?

[280plus]

Most likely. There were a LOT of typographical and technical errors in the 2000 International codes, which is why very few states ever adopted them. Most states waited for the 2003 editions, which had most (not all) of the screw-ups somewhat fixed.

Perfect. Why is it always me that manages to precisely pick the wrong thing? Of course, when I went into bizness and decided I needed a code book 2000 was the most up to date manual there was. I guess that's why I got it. I don't amember.

[Tallpine]

Our chimney/pipe is at the eave and doesn't reach higher than the peak.

If it did, I would need a bucket truck to be able to clean it...