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100+ year old chimneys


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I expect that most of us have probably noticed that old chimneys (over 100 years old) are often twisted slightly at the top. I've always heard (and believed) that they twist in the direction that the sun travels (east to west).

This morning I inspected a home built in 1850 and my egghead client wanted to know exactly why and how this occurs. I couldn't tell him, but I thought I'd see if any of you folks know.

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Jim,

I'm not sure what you mean by twisted as I only (frequently) see what I would describe as leaning.

There are 2 theories:

- Sulphates from the exhaust of solid fuel condense on the coldest side of the chimney causing expansion in the lime based mortar joints.

- Erosion to the mortar joints occurs on the prevailing wind/rain side of the chimney.

You can see this in the older sections of any eastern city. Look at rows of identical 100+ year old homes and all their chimneys are leaning in the same direction. I have never taken the time to correlate which direction.

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Sadly we don't have ROWS of 100 year old houses here, but now I won't be able to look at ones' chimney without checking for lean or twist in a particular direction. "Following the sun" sounds goofy, but you never know... If that's it, I should be able to see down here for sure.

Brian G.

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Originally posted by inspecthistoric

Jim,

I'm not sure what you mean by twisted as I only (frequently) see what I would describe as leaning.

There are 2 theories:

- Sulphates from the exhaust of solid fuel condense on the coldest side of the chimney causing expansion in the lime based mortar joints.

- Erosion to the mortar joints occurs on the prevailing wind/rain side of the chimney.

You can see this in the older sections of any eastern city. Look at rows of identical 100+ year old homes and all their chimneys are leaning in the same direction. I have never taken the time to correlate which direction.

All the old chimneys in Portland, Oregon lean to the south. Every time. I've heard a half dozen explanations including the two you've mentioned, one having to do with moss growth affecting the mortar, one having to do with magnetism, and two relating to government conspiracies.

Jim Katen, Oregon

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Originally posted by Jim Katen

Originally posted by inspecthistoric

Jim,

I'm not sure what you mean by twisted as I only (frequently) see what I would describe as leaning.

There are 2 theories:

- Sulphates from the exhaust of solid fuel condense on the coldest side of the chimney causing expansion in the lime based mortar joints.

- Erosion to the mortar joints occurs on the prevailing wind/rain side of the chimney.

You can see this in the older sections of any eastern city. Look at rows of identical 100+ year old homes and all their chimneys are leaning in the same direction. I have never taken the time to correlate which direction.

All the old chimneys in Portland, Oregon lean to the south. Every time. I've heard a half dozen explanations including the two you've mentioned, one having to do with moss growth affecting the mortar, one having to do with magnetism, and two relating to government conspiracies.

Jim Katen, Oregon

I'll take goverment conspiracies to win, magnetism to place and moss to show.

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I've seen a plenty of leaners too, and it may be that the twisted ones look like they're leaning from the ground, but if you get up close and personal with a bunch of really old chimneys, I suspect you'll see what I'm talking about. A whole bunch of them are twisted slightly from the roofline up.

I wondered if there was a generally agreed upon, factually based, and scientifically backed up reason for this phenomenon, and if I ever find one (or make up a really good one) I'll post it and attempt to take credit for it's discovery by calling it: "The Morrison Effect" Stay tuned...

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When you say twisted, you mean like a spiral, right? I get up close & personal w/ a lot of very old (100+ years) chimneys, like about 3 to 5 a day; I'm not sure I've seen a spiral.

There could be an aerodynamic theory behind it. When I strap gear to the top of my car, I always give the web strap a twist so it doesn't vibrate & hum when I'm blazing down the expressway.

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Originally posted by Jim Morrison

...I'll post it and attempt to take credit for it's discovery by calling it: "The Morrison Effect" Stay tuned...

Oh sorry, that one's already taken. "The Morrison Effect" refers to the tendency of stocks of Guinness to dwindle in the vicinity of certain Irish-American home inspectors... [:-mischievous]

Brian G.

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Originally posted by Jim Morrison

Kurt,

As city dwelling ladder monkey, you see more old chimneys than I do. But, yes, I'm talking twisting a la Chubby Checker as opposed to leaning a la Tower of Pisa.

Aerodynamics is another theory bearing exploration. What kind of mileage to Chicago area chimneys get, anyway?

Calling someone a "ladder monkey" in the wrong instance in my City could get you shot; since we aren't in my City, I'll take my finger off the trigger, stop jittering, stub out my cigarette, & figure you was just one of them Easterner's who forgot who they were talking to.

Ahem.....

We get about 100 years to the mile of masonry around here, young pup.

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