Rebuilding a Chimney Crown


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Old 06-09-08, 02:02 PM
L
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Question Rebuilding a Chimney Crown

Here's my situation.
40 year old brick chimney with single clay flue and concrete crown. Chimney no longer used as converted fireplace to vent-free gas logs.
The crown and top 3 row of bricks were severely cracked. Removed crown and 3 rows of bricks.
have replaced 3 rows of bricks with new mortar.
Question - how do I properly support the crown when I pour the concrete crown? I know how to make my form for the sides including a 2 inch drip edge. Problem is it appears the prior crown was supported by 2 x 4's that were resting on nails located on the inside of the chimney. After 40 years the nails and wood have fallen to the bottom of the chimney!
I guess I could use wood again but surely there is a better way. I though about a piece of steel but that will be expensive and hard to find/cut. I also worry that the wood will make the concrete dry to quickly causing cracks.
The chimney is 5ft by 2ft with a 12 inch flue in the middle - I plan to retain the flue even though it is unused.
Thanks for any ideas.
 
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Old 06-09-08, 02:58 PM
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Doesn't the flue extend up beyond the crown? It is not clear why boards had to be used beneath the crown.

Here is a link to some good instructions. I seem to recall that I posted this link years ago and someone pointed out that they forgot to tell you to remove the form.
http://www.handymanclub.com/Projects...t.aspx?id=1992


Photo Credit: Popular Mechanics

Read tips here: http://www.popularmechanics.com/how_...c/1275246.html

A chimney cap is also recommended. The cap keeps weather, leaves, and wildlife out of the chimney.

Photo Credit: Black Chimney Caps

 
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Old 06-10-08, 07:58 PM
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Appreciate the response. The flue is only about a 12 inch square and yes it extends past the crown. The chimney is 5ft by 2 ft. There is no way to pour a new crown without something underneath to support it until it sets.
The bricks are standard width so the "air" space is approx 18" by 4ft 6" (minus the 12" by 12" flue).
Back in 1962 they used wood to support it. It lasted 40+ years so I guess I could use plywood but I was hoping there was a better solution.
Thanks.
 
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Old 06-10-08, 08:24 PM
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Most sweeps and masons I know use metal lath with a scratch coat, then pour over that.
 
 

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