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Measuring 3-2-10

New postPosted: Fri Sep 02, 2011 2:29 am
by Marc M
I just wanted to verify this;
if I was measuring an existing chimney to an adjacent roof deck, would it make sense to go down 2 feet then out 10?

Re: Measuring 3-2-10

New postPosted: Fri Sep 02, 2011 1:32 pm
by Jerry Peck - Codeman
Yes, but ...

... where do you start measuring from - see annotated photo.

3-2-10 rule.jpg

Re: Measuring 3-2-10

New postPosted: Sat Sep 03, 2011 1:11 am
by Marc M
Wow..nice job. Didnt know you were an artist too.
So in your photo, the chimney is short correct? Assuming the 10' mark is correct. ( Lets just say it is for S&G )

Re: Measuring 3-2-10

New postPosted: Sat Sep 03, 2011 11:42 am
by Jerry Peck - Codeman
Marc M wrote:So in your photo, the chimney is short correct? Assuming the 10' mark is correct. ( Lets just say it is for S&G )


*Assuming* my 10 foot mark is correct, yes, the chimney is too short.

I estimated the 10 foot mark based on typical shingle exposure and a 3/12 slope, that appears to be no greater than 3/12, and then did a '10-feet-ought-to-be-about-here' guess. Same applies to the chimney height, but I may be further off on the height because I didn't know if those 'bricks' in the chimney were 4 inches high or 6 inches high, and that makes a big difference in height.

I was hoping the 10 foot mark being drawn at the top of the chimney was not confusing as it is measured at the 2 foot down mark - but that would have complicated what was being shown at the 2 foot down mark as the roof to the right does not look to be 10 feet away at that level.

If a chimney on at a flat roof, then it needs to be 3 feet high minimum above the flat roof (higher if there is any part of any structure within 10 feet) - this also applies to a chimney with the flue at the ridge, you measure down to the ridge for the minimum 3 foot height.