Thread: Chimney Height

Currently masonry chimney height requirements are 3' or 2' higher than roof/wall within 10'. Does anyone know how long this code has been around? The reason I ask is because I see lots of what appear to be 50-60's era homes with chimneys in my area that appear to be no higher than 18-24" I am curious to know if these were built correctly in their time or if the AHJ wasn't paying attention, and also would you report something like this?

One other question- I know it was long before my time, but anyone have any guess on when S-traps were outlawed?

Thanks for your help.

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Bob Harper can probably give you the answer to how long that has been required, however, what is more important is that - for however long - it is recognized that chimneys are DANGEROUS and require at least those minimum heights.

What that means is that a chimney from 1800 which is only 1 foot higher than the roof *is any not safer* than a chimney from 2010 which is only 1 foot higher than the roof ... i.e., just because something may have been allowed prior to realizing it was wrong does not make it 'not wrong'.

You should be writing them all up, regardless of how old the chimney is, and, in fact, the older the chimney is, the more likely there will be problems with it and the more dangerous it will likely be, and being shorter just makes matters worse.

If I remember correctly, it was first required in the 1915 Field Practice Manual, Chapter VII from the NFPA Cmte. on Chimneys and Flues, which was the precursor of NFPA 211. It was also in the 1927 Uniform Bldg Code if I am not mistaken.

The three foot minimum is intended to provide sufficient cooling of sparks before they reach a roof surface. The 2/10 function addresses adverse wind pressure regimes regardless of roof pitch. Note these are minimum standards that may warrant exceeding by a considerable amount depending upon the requirements of the appliances.

As JP said, if it's wrong, its wrong regardless of age. Now, if you're into litigation and researching it against the actual date of construction, that requires some detailed work. Dale Feb would be the expert on such matters.

HTH,

Originally Posted by Bob Harper

Now, if you're into litigation and researching it against the actual date of construction,

I would NOT want to be on the side of having to research that to be in a position to say that it is okay for a chimney to be only 1 foot above the roof because the code had not YET recognized the inherent hazard it presents ... I would turn that work down rather than be on record saying it was okay, then have the house burn down because the laws of nature failed to understand that it was not allowed to burn down because - 'back then' ... it was okay.

Originally Posted by Bob Harper

If I remember correctly, it was first required in the 1915 Field Practice Manual...

Bob, you're not THAT old are you?! Ha!

Merry Christmas all you guys and gals! Hope Santa brings you what you want as well as what you can actually use.

Thanks for your help

Merry Christmas!