B-vent spacing to roof

[msteger]

I ran across this B-type metal vent today connected to an LP stove. Due to the steep roof pitch, I could not get closer to get an actual measurement, but it appeared to be approx. 3'~3.5' between the top of the B-type vent and the adjacent ridge. Horizontally, the top of the vent was just a few inches above the ridge shingles. Estimating just over a 12/12 pitch, I'd expect to see a 5' spacing b/w these two. Am I correct?

See the attached photo.

Due to the LP service being off, I couldn't fully test the LP stove, so I recommended service by a qualified technician.

Thanks.

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[Brandon Whitmore]

I don't think the sidewall is an issue here. It looks like that roof is right at a 12/12 slope. 11/12 - 12/12 requires a min. 4' height, 12/12- 14/12 requires a 5' min. (Figure G2427.6.3)- (503.6.4) Page 400 of the '06 IRC

[Chad Fabry]

The apex is an acute angle; the roof is at least a 14:12, maybe steeper.

[msteger]

Yeah, it looked to be a little over a 45 deg angle, so that is why I guessed about a 14/12 pitch. That is why I figured it should be 5', not the 3~3.5'.

I know there are lateral spacing requirements (like b/w a metal B-vent and a dormer side wall), but I am thinking the height requirement of the vent itself when comparing it to the roof pitch addresses this horizontal spacing issue (as long as it is only a roof, and not a dormer near it). So, was I correct to say the spacing is a little too close?

[Brandon Whitmore]

I know there are lateral spacing requirements (like b/w a metal B-vent and a dormer side wall), but I am thinking the height requirement of the vent itself when comparing it to the roof pitch addresses this horizontal spacing issue (as long as it is only a roof, and not a dormer near it). So, was I correct to say the spacing is a little too close

I don't quite understand the spacing question. Spacing would be between a vertical wall and the vent. It looks like the only thing that applies here is the vent height requirement above the roof.

[Brandon Whitmore]

The apex is an acute angle; the roof is at least a 14:12, maybe steeper.

Man I hate being wrong. I just pulled out my protractor. It's well over a 12:12...........

[msteger]

I guess that is my question, Brandon. Since there is no sidewall (like an adjacent dormer) present, the horizontal spacing requirement to the roof doesn't come into play here. We are only talking about total height of the vent above the roof (where it passes through). The calculation of the pitch of the roof is what determines if the vent is tall enough (and in reality, far enough horizontally) from the adjacent roof ridge. That was my real question..sorry if I made it more confusing than it needed to be.

Thanks.