Pouring a concrete cap for a chimney HELP - Contractor Talk - Professional Construction and Remodeling Forum

young_mason · 08-18-2009, 04:34 PM

Hey i'd like to start forming and pouring a concrete cap instead of using a pre-cast concrete cap, could someone please give me a walk thru tutorial?

Thanks!

tccoggs · 08-18-2009, 05:37 PM

Funny you should ask, I was just researching this myself a bit:

ftp://imgs.ebuild.com/woc/M930413.pdf

This is for my own house, buy I'm a wood guy, not a stone guy. I have an existing brick chimmney on my house which is about 19 years old, the crown looks like crap, and the top 3 courses of brick are shot. I had a mason friend of mine give me an estimate to repair the crown and cover the chimney in cultured stone. What I was pretty surpised about was the lack of knowledge regarding the manufacturers recommendations regarding clearance to the roof and flashing at the top. I have to dicuss with him more, but he wasn't exactly filling me with confidence.

**Ed the Roofer** · 08-18-2009, 08:16 PM

Quote:

Originally Posted by tccoggs

Funny you should ask, I was just researching this myself a bit:

ftp://imgs.ebuild.com/woc/M930413.pdf

This is for my own house, buy I'm a wood guy, not a stone guy. I have an existing brick chimmney on my house which is about 19 years old, the crown looks like crap, and the top 3 courses of brick are shot. I had a mason friend of mine give me an estimate to repair the crown and cover the chimney in cultured stone. What I was pretty surpised about was the lack of knowledge regarding the manufacturers recommendations regarding clearance to the roof and flashing at the top. I have to dicuss with him more, but he wasn't exactly filling me with confidence.

The steel crown forms pictured on Page 2 of your link would not allow for the proper amount of overhang fro a drip edge away from the lower brick structure.

The components needed to use the kit are available through Copperfield Chimney Supply or you can make your own forms out of lumber.

Ed

tccoggs · 08-18-2009, 10:50 PM

Ed,

I noticed they were being a bit cheap with the overhang.

Any thoughts on my cultured stone detail where it meets the roof???

Owens Corning wants a 2 inch gap to the roof, I imagine for both settling and freeze/thaw water issues. I was thinking a ACQ 2x3 curb around the base of the chimney, then forming a copper z flashing over the curb and kerfing the masonry and letting in the tab into the masonry. Weather and ice over the top flange that will then be covered with wire mesh, scratch coat and then the stone. The shingles can then be step flashed under the z-flashing.

Am I crazy?? The existing masonry was done with aluminum and looks like garbage as it was all hand bent