chimney issues

[John Dirks Jr]

Does the cracked crown cause the damage to the liner? If not, what do you think caused the damaged liner?

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[Tim H]

Hi John,

It is possible that water penetrated the cracks in the crown, and then froze (and expanded). The expansion moved the crown, and the crown then crushed the flue liner.

Tim

[Chad Fabry]

The mason didn't use a bond breaker between the flue and the crown. When the cap cured it bonded to the flue. When the flue gets hot it gets taller and the whole mess, flue, crown et al moves up and down. Masonry is, as a rule, opposed to being moved around.

[Tim H]

Originally posted by Chad Fabry

The mason didn't use a bond breaker between the flue and the crown. When the cap cured it bonded to the flue. When the flue gets hot it gets taller and the whole mess, flue, crown et al moves up and down. Masonry is, as a rule, opposed to being moved around.

D'oh.

As they say around this part of the country; "if it was a snake, it would have bit me".

Tim

[Erby]

It must be late. I read Chad's statement as "they didn't use a bone breaker between the flue and crown" and moved on to the next thread. Then, and only then, did it hit me that the statement didn't make a damn bit of sense and had to come back and see what he really said.

[John Dirks Jr]

I learn so much by posting pictures which draw responses. I guess posting more often would be a good habit to get into. See, I learned something right there.

[Chad Fabry]

It must be late. I read Chad's statement as "they didn't use a bone breaker between the flue and crown" and moved on to the next thread. Then, and only then, did it hit me that the statement didn't make a damn bit of sense and had to come back and see what he really said.

I'm a little hurt that you're used to reading what I write and then moving on without understanding what I was getting at.

I could almost hear it from here

"Bone breaker belly acher, I'd love to hire someone to break Fabry's bones.

[Brian G]

All chimney caps look like that around here, but damaged flue liners are very rare. Would lack of a bond breaker normally damage the second liner section too? What does a bond breaker typically look like? Got a photo, anybody?

John, your lack of over-sensitivity to constructive criticism continues to serve you well (and others). Keep it up.

Brian G.

Circuit Breaker, Vacuum Breaker, and Now Bond Breaker [:-crazy]

[Bill Kibbel]

Originally posted by Brian G

What does a bond breaker typically look like? Got a photo, anybody?

I can show you what it's supposed to look like. I've never seen one actually done (most chimneys I see don't have flue liners and the few that do, never, ever have the break).

[Chad Fabry]

What does a bond breaker typically look like? Got a photo, anybody?

Around here most masons that are aware of the issue use a piece of felt between the crown and flue. Pretty much anything that prevents the two from sticking together works well.

There are products specifically intended for use as a bond breaker in other areas like between the house foundation and the garage slab. I've seen literally dozens of homes where the top course of block was lifted because it was attached to slab and the edge curl levitated the whole shebang by a 1/4 inch or more.

Anyway, I should have tempered my remark by inserting a 'maybe' or an 'it's likely' somewhere. I see tons of chimneys just like the one in John's photo and the root of most broken crowns and flues is poor building practices; especially the lack of bond breakers.

[Bain]

An exceedingly accomplished mason explained the necessity of bond breakers to me many years ago. Other than his work, though, I've never seen another chimney that contained a bond breaker.

[Brian G]

Ah-so. Thanks Bill, Chad, et al.

Brian G.

Yet Another "Best Practice" Being Universally Ignored [:-dunce]

[Bain]

The other best practice being ignored in John's photo is that the crown is mortar, not concrete.

Mortar is porous and absorbs water, which of course expands when it freezes and exacerbates and/or causes the cracks in the photo.