Im sure this rule still applies to a metal roof just dont understand why. I doubt that anything that could get through my cap screen could land on the roof and be hot enough to light a fire on the underlayment. is there any logic behind it?
10-3-2 rule on metal roof
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You're expecting logic and regulations to have some relationship? I'm quite sure it's 'for your own good', and that the bureaucrats know what you need. I have a friend with an artesian well, solar hot water, and a septic system. Kind of hard to figure out why the government won't allow him to purchase a high-flow kitchen faucet.
Maybe someone out there can cite data that shows the need for such a rule in your situation, but I wouldn't hold my breath.
Maybe someone out there can cite data that shows the need for such a rule in your situation, but I wouldn't hold my breath.
Well better release your breath before you die.
It has very little to do with spark protection, but draft. If wind hits you roof it can deflect and cause a vacuums a near the surface on the leeward side of a roof. It can also deflect and apply positive pressure forcing a down draft. It has been factored to reduce the effects of roofs and other structural parts of the building that the chimney needs to be 2' higher than any part of the roof or structure within 10'. Remember this is the bare minimum. Many times unique situations miminun is not enough and this height needs to be exceeded to draft.
If you are in a district that requires spark arrestor's ,it is usually achieved by a spark arrestor cap and not height
IT's ok to exhale if you are still amongst us
It has very little to do with spark protection, but draft. If wind hits you roof it can deflect and cause a vacuums a near the surface on the leeward side of a roof. It can also deflect and apply positive pressure forcing a down draft. It has been factored to reduce the effects of roofs and other structural parts of the building that the chimney needs to be 2' higher than any part of the roof or structure within 10'. Remember this is the bare minimum. Many times unique situations miminun is not enough and this height needs to be exceeded to draft.
If you are in a district that requires spark arrestor's ,it is usually achieved by a spark arrestor cap and not height
IT's ok to exhale if you are still amongst us
Well Ive got 26' of verticle pipe and im on the lowest point of the roof on the leward side. I dont think draft will be a problem. Although I could be wrong and maybe I need the height, in fact I have the pipe to do it. I just question if its necessary as close to 10' of pipe sticking out of the roof isnt the most attractive thing. Perhaps i could mount a flag on it. Why does the NFPA care about draft, shouldnt they be worried about fire?
nshif said:
what is the pitch on the roof? remember you only need 2 ft above any part of the roof within 10 ft not necessarily 10 ft of pipe unless this is a steeper pitch. also , if you are 2 ft higher than 10 ft circumfrence you might not have to clear the peak if you are say 15-18 ft away on a gentle pitched roof you may not even clear the peak
to answer why NPFA cares about draft, a downdrafting chimney or an insufficient chimney can allow back venting of stack gasses such as carbon monoxide (which last i checked can kill you), not to mention the lack of "horsepower " in a flue can lead to its getting loaded with creosote and be a possible candidate for a chimney fire. they arent just making these specs up just cause they like to see tall smokestacks, these are not only functionally related,they are also very much safety related. besides, without draft , you have no fire
Thanks Mike I guess I can understand that. Im more worried about too much draft. my roof pitch is 8:12 so it works out to a little less than 10' vert to cover the 10' horizontal. I think Ill still be below the peak because Im pretty close to the low side
nshif said:
i got ya bro. as for "too much draft" its far better than not enough , too much can be attenuated by the draft controls on the stove or installing a butterfly in the flue if its really extreme. as for the exposed pipe , maybe build a chase around it matching the wall surface , use same clearances you would in an attic you will likely need a support as well to help keep the pipe secure and standing too. remember 26 ft of pipe may still not draw if it is not set up correctly in relation to the roof. ive seen some pretty tall stacks that didnt draw in my time , but then i have 14 ft and it will suck small children up the flue if they get too close. but im 3 ft above the peak and 4 ft away from it (4/12 pitch).
Well I guess we will just wait and see what happens, I can only hope for the best and Ive alraeady thought of a butterfly damper if its too much.
and yes I already have extended roof supports to keep it there. Thought of a chase and maybe will do that, but building that close to 24' in the air isnt something i want to do unless i have to
and yes I already have extended roof supports to keep it there. Thought of a chase and maybe will do that, but building that close to 24' in the air isnt something i want to do unless i have to
nshif said:
i hear ya, well, let me know what you find out once you get burning, one of my best "stock in trade" functions is figuring out draft problems that folks run into with my products mostly due to installing a chimney without contacting me or coming in here first and learning from the pros. usually i can get them up and running. i'll help in any way i can if the need arises you know were to find me.
Thanks Mike Ill keep you posted, If it wasnt for the snow tody Id be burning tomorrow, but probably have a few days to go yet.
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