Why do old chimneys curl?

[mgbinspect]

A slow consistant curl in a chimney is a common observation in an old chimney constructed with lime mortar. Over time, the mortar is getting washed out and compressed on the sides of the chimney exposed to the most weather. Those sides of the chimney are actually becoming shorter, hence the curl.

[Les]

could also be thermo-dynamics. or as us old timers call it - the sun effect. The above post might be a good paragraph for the PTA or Lions Club, but a little weak for inspectors.

[mgbinspect]

Hey, Les!

Were it a thermal phenomenon, it would not be for the most part limited to old lime mortar chimneys. I'm fairly confident this is the cause for the following reasons:

1.) They always seem to curl to the most weathered side and on that side head and bed joints are often practically gone.

2.) It only seems to ocurr in unlined chimneys that don't enjoy the added structure of a terra cotta flue liner.

3.) Both the inner and outer surfaces of unlinded chimneys are exposed to the elements.

I'll exhaust your proposal though. And, no doubt the constant expansion and contraction of heat/use makes it all the easier for those joints to wash out.

[kurt]

I see the freeze/thaw side of it; one or another sides soaks up water, water freezes & expands, chimney leans/curls over.

[Jim Morrison]

Mike,

I've been doing inspections in an old housing market for a long time too, so I've sure seen my share of twisted chimneys.

I've never read a convincing explanation of why this occurs, and even though you present them as fact, yours are only guesses based on your personal experience, not science. No offense intended.

The search for answers continues...

[kurt]

What was that thread of a year (or so) ago where we were talking about twisted chimneys?

We know chimneys "curl" (personally, I don't like that term; lean, twist, bow, etc. seems more appropriate), but no one has a definitive answer.

We're as knowledgeable as anyone else out there about this stuff. I think it can be what Mike B. said, or freeze thaw; what else could it be? (looking for opines....)

And, more importantly, what about curling, as in Olympics? I mean, does anyone watch that stuff? Is it really a "sport"? Seems a little strange to me; kind of like really expensive SkeeBall or something.....

[chrisprickett]

And to think I had always accredited it to Santa's big fat butt...

[Les]

Wasn't "Twisted Chimney" a band in the late 70's?

Sometimes I wonder why I check this board daily and then I re-read my own posts!

[mgbinspect]

Ok, just spent 60 fascinating minutes on the phone with Ray Henderson a lab tech at Essroc corp. a maker of cements and mortars for years. He was referred to me because another lab tech that I know said he has an interest in old mortars.

I bounced my theory off him. After much discussion and thought he proposes that my theory may be a contributing factor, but that Kurt is probably closest to right. Freeze and expansion is over the years breaking the composition of the mortar and the bond of the mortar to the brick.

That was fun!

Regarding autogenous healing. It definitely is not as much a player in new mortars and cements as it once was. Autogenous healing does require water migration. Moisture is not enough. Water must travel and carry Calcium Hydroxide (which is quite soluble) with it to a void at an evaporation point where the calcium Hydroxide mixes with carbon dioxide to form Calcium Carbonate (no longer soluble). That is the new set point when healing has occured. He also likens the process to stalactite and stalgmite action.

And, off the subject but equally fascinating and enlightening, get a load of this...

He told a story about old masonry buildings up north (your way, Kurt) that were suffering accelerated damage to the brickwork due to.... of all things... the addition of good insulation to the exterior walls!! The masonry was no longer absorbing and radiating heat from the inside of the building out and began to abosrb and retain moisture and freeze and thaw.

Kurt gets the big prize and I feel no guilt over proposing theories based upon my experience.

Hey, somebody's got to have the gnads to propose the world is flat before we arrive at it being round.

Frankly, now these posts are true discussion and iron sharpening iron!

For Jim's sake, I'll begin to use the phrase, "I propose" or "I feel". [:-wiltel]

Until the next time the wagons circle around me... best wishes to all.

P.S. As "5" of Short Circuit fame used to say, "Input Stephane, Input!"

[Jim Morrison]

Kurt:

I've heard, and noticed that old chimneys seem to follow the movement of the sun (East to West), but can't back it up with any hard data, just personal observation.

Chris:

I think the technical term for Santa's condition is "Fatassatosis" He can't help it, it's genetic.

[mgbinspect]

All we need now is a potbelly stove... [:-slaphap

[kurt]

This is what a forum is all about; heads banging until some truth spills out. Like just about everything else, problems can usually be traced to water.

The most interesting thing was the story about new insulation on interior walls acclerating damage @ the exterior. Where can I find out more about that? Who was this guy w/the story? I need (and I do mean really, really need) to figure that out quickly.

[mgbinspect]

I've sent the name and number to you via private message Kurt.

Amen, mah bruthah.... I'm never satisfied with theories. I long for answers.

Good luck!

[Brian G]

Originally posted by kurt

And, more importantly, what about curling, as in Olympics? I mean, does anyone watch that stuff? Is it really a "sport"? Seems a little strange to me; kind of like really expensive SkeeBall or something.....

I actually watched about 10 minutes of that this year. It's just plain goofy. The Olympics are in serious need of a re-vamp, summer and winter (think "syncronized swimming" in the summer games, among others). [:-boggled

Brother Morrison is just being a true HI. It's critical for us (HI's) to know the difference between opinion and fact, and to always state them as such. Plus he's a natural-born ball-buster. [:-dev3]

Freeze/thaw as the primary culprit makes sense to me, since I hardly ever see a chimney like that down here. Usually I see them either tilting or settling, if anything. And while we're on it, what's the common fix for a chimney/fireplace that's tilting slowly away from the house? Can't they pump concrete or some thing under it to jack it back into position?

Brian G.

How About Syncronized Curling?! [:-dopey]

[mgbinspect]

If getting my balls busted yields revelation, I'm all for it. As I said, I'm not a big theory fan, I like answers.

Most of these stories I'm posting aren't about the story. Of course, the story is entertaining, but the conclusions are fascinating.

Brian, if it's actually a bowed chimney, "I feel" or "I propose" [].. There is no easy remedy. especially since the integrity of the flue would forever be suspect. It's probably best to remove and relay it. But, if the entire chimney is leaning away from the house, yes that can be pretty easily fixed. We have a lot of shrink/swell soil around here and what they normally do is sink a couple of heliptical piers down into the ground until they hit a desired resistance and then jack up the chimney and clamp support angles under the chimney footing and to the piers.

Also, when it's shrink/swell soil in subside state, I've actually instructed people to leave the hose trickling all night at the base of the chimney and they woke up to a chimney that was straight up against the house again in the morning. (Obviously a temporarly fix. Ya gotta stabilize that one.)

Now truly, If someone gave me no option but to repair or right a bowing chimney, I guarantee you I could accomplish it. It would be costly, though. I've been involved in some pretty wild things. We once moved two railroad buldings and a huge (and I do mean huge) mill all (turn of the century buildings) into the center of Leesburg, VA and built new foundations under them all to form a downtown attraction. (shops)

You'd be amazed what a master can do in any trade! I once watched an 80 old man and his young assistance remove and replace two of the bottom logs from a very old log cabin with merely a few rocks, bags of cement and a big log as a fulcrum! Now, that was a master using techniques passed along.

[Les]

There has been an error!!!!!! I, Leslie E Van Alstine, proposed "kurt's" theory first. I want my prize!

Actually, we all are right and we all gained from the discourse. Mgbinspect has proved himself to me and I do appreciate his input and candor.

thanks

[mgbinspect]

Why thank you, Les. I'm touched. This has been a very productive discussion. I'll take the wagons circled around me to idle chit chat any day.

Can someone pass me another log for the stove?...[:-slaphap

"Input... Input..."

[hausdok]

Hi,

Actually, in my market, I'm down with the first explanation. I get a ton of old leaning unlined stacks on old bungalows here and they all invariably lean to the south where our prevailing wind and rain comes from. It's real common to be able to sink a pick right up to the hilt and rake mortar out on the weather side of one of these weathered stacks and on the other side it will barely penetrate. The worn out/cracked crown are major offenders too. Once they start taking water, it's not long before the mortar starts losing cohesion, softens and starts compressing.

Anyway, that's the way it seems to be here on Puget Sound where there's a ton of moisture and it hardly ever actually gets down to freezing temps - even at night.

ONE TEAM - ONE FIGHT!!!

Mike

[mgbinspect]

Oh.. no... we're back to square one... Which vindicates me somewhat... but... is it chicken?... or egg?...

[kurt]

I think it's clearly both; in my area I see foundation defects that can be traced to powdery mortar spilling out of joints w/resulting settlement, but chimneys can (pretty much always) be figured w/freezing as the culprit.

What's really important here is that Les (the old timer) was not right. I claim rightness as mine; all hail Kurt, the Right One.

[Brian G]

Originally posted by mgbinspect

If getting my balls busted yields revelation, I'm all for it. As I said, I'm not a big theory fan, I like answers.

That's an approach I can appreciate. Any reasonable person has to willing to entertain and consider new or differing information without taking it personally. Good show Mike.

But, if the entire chimney is leaning away from the house, yes that can be pretty easily fixed. We have a lot of shrink/swell soil around here and what they normally do is sink a couple of heliptical piers down into the ground until they hit a desired resistance and then jack up the chimney and clamp support angles under the chimney footing and to the piers.

For whatever reason I see these here and there in my area; still straight as an arrow, with the whole thing slowly tilting away from the house. Often the gap has been caulked at least once, and has re-opened (of course).

Also, when it's shrink/swell soil in subside state, I've actually instructed people to leave the hose trickling all night at the base of the chimney and they woke up to a chimney that was straight up against the house again in the morning. (Obviously a temporarly fix. Ya gotta stabilize that one.)

We do have some specific areas of expansive soils around, so I'll keep that in mind too.

Brian G.

Tilt Belongs on Pinball Machines [:-mohawk]

[mgbinspect]

Typically, Brian that is the result of an add-on chimney with a footing that was either not deep or wide enough. I was always worried about that whenever I did an add-on fireplace and would always not only go to the required footing depth but pour a very spread footing (usually twice what was required) just be sure that it would remain stable.

[mgbinspect]

Ok, Kurt, that was funnier than my joke. lol Thanks

[Garcha]

This thread actually reminds me of curling. Long, slow and tedious with continual brushing from side to side, while noone really understands the reason for the game never mind how to keep score.[:-sly]

[Bill Kibbel]

On the other side of the pond, where I've learned the most about old masonry, the debate over the direction of the "leaning stack" has been going on since before the first brick was fired on this continent.

The statement that they all lean towards the prevailing wind and rain is the usual explanation heard in the US. The conditions directly around each individual chimney and within the flue is what dictates which direction the chimney leans. The most common tendency is to lean toward the center of the building.

I have seen this in old towns where chimneys on buildings in the same block do not all lean the same direction. It is also common to see Georgians, with the paired chimneys at each gable, all leaning toward the roof.