Clearance Problem For Chimney

GregWCIL

I have a debate with my masonry subcontractor. Here's the situation:
We need to install a full (4 in. thick) split ledgestone facade for a chimney. The actual chimney inside is double wall insulated stainless rated for 2 in. clearance to combustibles.
The stone chimney facade will start above the fireplace, will rest on top of a concrete cap and will only be 8 ft. tall to the vaulted ceiling.
Originally we were going to use 4 in. block behind the stone, but this turns out to be a problem in keeping the chimney facade dimensions down to what they need to be.
Can we build a steel stud inner wall, covered with durock and build the stone chimney against that using brick wall ties? The structure would be entirely inside the house so the steel stud/durock would really mainly be for support until the mortar and stone sets up.
Is there code on this?
Thanks,
Greg

jomama

Maybe it's just me, but I don't understand. You have room to fit a 4" steel/durock wall but not enough room for a 3 5/8" block wall?

jvcstone

Maybe they are talking about straddling the steel flue with the studs so that the durorock is not actually 4 inches in front of the flue--could get the clearance needed that way. I suspect that if it is just a facade, and nothing structural, that would work.

JVC

__________________
John VanCamp
www.jvcstoneworks.com

GregWCIL

Yes, John, I did plan to straddle the SS flue with the studs.

However, after more discussions with the mason and carpenters today, we decided to play it safe and back the stone up with a block wall. The SS flue was going to have an offset in it up higher to clear a roof truss. By moving the offset lower we can maintain our original 4 ft. wide chase and still have room for the block.