Calling all chimney experts!

[RS267]

Some of my colleagues and I have a "friendly disagreement" as to whether or not a particular chimney setup meets the 3-2-10 rule. I will spare you the details of our discussions (for now) so as not to influence anyone's response. All other aspects of the setup are in spec as far as minimum height, clearance to combustibles, straight up totally interior chimney, attic insulation shield, etc. The only bone of contention is the 3-2-10 rule. The scenario: Type HT chimney pipe exits the decking of a roof that has a 12/12 pitch. The pipe extends 3' above the roof deck and is 2' horizontally from the peak of the roof. There are no other buildings, trees, etc. at issue. What say you? (no pressure, but there's a 6 pack of Sam Adams riding on your answers Thanks in advance for your replies!

 

[thechimneysweep]

If the peak of your roof is within 10' of the chimney, the chimney must extend 2' above the peak.

 

[blackgooseJT]

10-2-3 is inclusive. The chimney must comply with all, not some. It must project no less than 3 feet out of the roof deck, AND it must also end at least 2 feet higher than any structure within 10 feet. If it is two feet from the ridge, it must also end at least 2 feet higher than that ridge in order to meet 10-2-3.

blackgooseJT

 

[jpl1nh]

If I'm understanding you correctly, the top of the pipe is 1' above the roof peak and the roof peak is 2' from where the pipe exits? I'm not an expert but Tom and Blackgoose are. Sounds like it doesn't meet requirements.

 

[crazy_dan]

sounds like he needs another foot or two of chimney. It will keep him safer and help with the draft so it is a win, win situation.
hope you said he needs more height or you buyin the beer.

 

[RS267]

I understand all of the above. What's at issue is where do you measure the 10' and I don't believe NFPA 211 is particularly clear on this. Why would you measure anywhere but at the termination, which is where any influence would take place? Measuring from a sealed point on the stack doesn't make any sense to me. In this particular scenario, there is nothing within 10', horizontally, of the termination, and there's 3' of stack above the roof.

 

[blackgooseJT]

But the end of the stack is not two feet higher than anything within ten feet of the stack. In your scenario you have met the first requirement of minimum height out of the roof, but have not yet met 2 feet higher than anything within 10 feet. Pitch of the roof is immaterial. If you use a ten foot rod and a level, start at the flue outlet and proceed down the stack on the ridge side. If you can do that with the rod horizontal and not contact any roof structure and can measure 2 feet of chimney above that line on the stack, you have complied with the standard.

blackgooseJT