Proper Chimney Crown construction

[fire_man]

I plan to pour a new crown on top of my 6'x3' wide rather large chimney.
I will build a form so that it will have a 1.5" overhang and I was planning for it to be 4" thick of concrete mix.

What is the proper way to build a base to support the crown when it gets poured?

1. I was planning on using 2-3" wide 1/8" thick steel bars (not angle iron).

2. How far apart should the bars be and what material goes on top of the bars - galvanized steel mesh or cement board or what?

3 What is the right way to create the bond break between the concrete slab and the brick?

 

[begreen]

Search on - chimney crown. There have been some good threads in the past on this topic. Here is one that may be helpful.
https://www.hearth.com/talk/threads/how-do-i-work-on-the-top-of-this-chimney.165684/

 

[fire_man]

Thanks for the link. I already read most of those articles and found some really good stuff.

One thing that surprised me was something bholler said "The brick institute no longer recomend metal reinforcement in crowns. Fiber reinforced concrete is prefered"

I reaearched fiber reinforced concrete and most articles said unsupported concrete should still have reinforced steel. It's considered unsupported unless on a solid and properly packed down base which I guess applies to a crown depending on how well the base is made.

 

[begreen]

Our entire garage floor is fiber-reinforced cement. The stuff works.