Hearth weight on top of Durock?

[6fthook]

Hello everyone,

I FINALLY started my fireplace project, and just finished framing out the hearth with 6" 16 and 18 gauge steel tracks/studs. It will go over a slab of concrete which I poured the other day after building a wooden form against the chimney.

The buildup of the hearth starting bottom up will be this: concrete, single layer of 1/2" Durock cement board, steel stud framing, 3 or 4 layers of Durock (thinset together and screwed down to the steel frame with no matching seams), then slab of 1.5" thick bluestone (7' x 20" about 250lbs).

Do you think it is ok to put that much weight on three layers of Durock? I just want to make sure they will hold their shape and will not shift over time.

The reason for the 3-4 layers of Durock is for more R-value, but mainly to build it up so the bluestone will match the height of the firebox.

Thanks for any guidance you can provide!

 

[mhrischuk]

Durock is cement. I think I would have just did the whole thing in cement.

To answer your question, since it's cement board it will handle any wood stove no problem in many layers.

 

[go_home_red]

What's the spacing between the steel "studs"? I went with 5" centers. There's three layers of Durock on top of that, and then four 1.5" thick slabs of concrete--and it's done fine.