Squisher
Minister of Fire
I am always very reluctant/cautious to trust my life to a masonry chimney. Some can be a lot more wiggly then they look at first glance.
How do I work on the top of this chimney?
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Exactly what my point was from the start. When you work on chimneys all the time you learn not to trust anything.
So does this mean if I use Fiber reinforced concrete I should NOT use wire mesh or rebar?
Is this the stuff: (broken link removed)
Yes use fiber not mesh. I dont know anything about the premixed stuff i have always mixed my own.
Myself and partner witness it.We were stun.The roller knocked a brick out of the chimney.Sounds crazy.It was crazy
On youtube there's all types of riggings used to work on chimneys that keep one from putting weight on the chimney.I will never put my weight on a chimney.They can look strong but don't trust it.Invest in safe rigging.
If you don't trust your weight on your chimney, why would you trust your chimney near your house? Makes no sense to me since any normal wind load would be more force than a person could exert.
Squisher
Minister of Fire
A human, ladder, whatever can inadvertently put pressure on a chimney that no shared windload would ever replicate I would think.
Regardless, if I was worried my weight would topple a chimney, I would not trust that same chimney on a windy day.
Squisher
Minister of Fire
Sure your call. Off the top of my head I can think of numerous chimneys that aren't blowing over but I would never consider trusting putting a ladder on. One in particular comes to mind where I watched the whole thing wobble and almost topple as a installer was putting a liner down from a lift. That's my parents chimney and it was about ten years ago that the liner/insert went in. Despite the winds best effort it hasn't blown over yet.
Well I took some good advice from this thread and went with scaffolding rather than a ladder.
I might start another thread to detail the work I am doing.
Now let the project begin!
![[Hearth.com] How do I work on the top of this chimney?](https://www.hearth.com/talk/data/attachments/227/227578-dbbfad021165b9dbc6286591b3d46733.jpg?hash=aFfc6wMep9 "[Hearth.com] How do I work on the top of this chimney?")
I might start another thread to detail the work I am doing.
Now let the project begin!
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VirginiaIron
Minister of Fire
Looks good.
While you are there you might want to examine the condition of AND height/type of the cricket flashing. That chimney is wide and at the base of your roof.
While you are there you might want to examine the condition of AND height/type of the cricket flashing. That chimney is wide and at the base of your roof.
The cricket was rebuit about 5 years ago.
I just started the demo. The crown is 5 inches of concrete on top of 4 inches of cinder block on top of angle iron.
Side view of crown shown below. Its very solid except at the feathered edges near the brick. I think that is the area it failed and let in water.
![[Hearth.com] How do I work on the top of this chimney?](https://www.hearth.com/talk/data/attachments/227/227613-f77064bbd94402a7992d5074b7d89d67.jpg?hash=WIhrRcvpBs "[Hearth.com] How do I work on the top of this chimney?")
I just started the demo. The crown is 5 inches of concrete on top of 4 inches of cinder block on top of angle iron.
Side view of crown shown below. Its very solid except at the feathered edges near the brick. I think that is the area it failed and let in water.
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Does anybody know why the need for a bond break is never mentioned when pouring a non-overhanging concrete crown (see previous post picture) ? Is it because non-overhanging crowns are not usually done with concrete and i have an unusual setup?
Because the brick structure the clay liners and the concrete crown all expand at different rates. Over time this can cause damage.
I have a poured concrete crown but its inside the brick and not overhanging.
Its just feathered using concrete to the brick edge. How should you do a bond break on that?
Should I feather the concrete using mortar on top of the brick?
Its just feathered using concrete to the brick edge. How should you do a bond break on that?
Should I feather the concrete using mortar on top of the brick?
A bricklayer I once knew would lay the top several courses in a mortar with a higher portland ratio and less sand and a feathered cap of the same strong mix. Something about the more sand the more water it would be prone to absorb. He had his own special "recipe" for it. He humped it in the center and sloped it to the brick's edge for runoff. He never poured an overhanging cap unless the house designer specifically called for one. He built probably thousands of chimneys in the most upscale developments over his career. A thick overhanging cap is quite rare in these parts actually.
Most masons dont do proper crowns and that is why we spend all summer rebuilding the tops of chimneys many of them only 15 to 20 years old. Wash crowns simply are not very durable. And mortar that is to hard causes just as many if not more problems than soft mortar.
He bricked the addition at my parents house and built the chimney for their fireplace in summer of 1980. The crown is still in great shape so far. The fireplace chimney in the original part of the house was done the same way in 1966. It did need a little touchup around the thin edges one time about 15 years ago but you can tell that the mason that did that one used more sand in the mortar. You could easily tell there was more sand in it just by looking. No doubt a thicker poured overhanging crown is the best way, but it is possible to get good service life out of what you called a wash crown. Nothing lasts forever. And it keeps you in work!
VirginiaIron
Minister of Fire
From what I know that infilled area ought to be of some loose material filled level with the exterior masonry, and the concrete cap/wash poured over that. The bond break between the concrete and the brick permits the concrete to slip as it shrinks while the bricks expand. The bond break can be paper or other material. Without that break, the joint at the bricks and concrete will eventually deteriorate. Additionally, many clay liners fail because the mason failed to permit room for verticall and horizontall expansion. For example, a clay liner should have a soft joint between the liner and the crown. My metal liner also requires consideration for verticle expansion.
Needed yes but there is no way to do it and keep the crown water tight. This is why wash crowns usually fail around the edge. And or crack from the corners of the clay liner.
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