# Cement board over drywall



## fakie99 (Nov 18, 2008)

Project coming up where we'll be installing cultured stone above an existing fireplace (surface is drywall). We need to match the width of the fireplace, but the studs in the wall that will have stone applied dont quite make it to the edge of the fireplace below. I'd like to install cement board rather than mesh and scratch coat (more $ but a time saver and seems more sturdy) right over the drywall. how far past a stud would you feel comfortable letting the cement board hang by (to get to the width dimensions we need)? with mesh it really cant hang past a stud at all, but with cem board, I'd feel a little more comfortable letting it hang over a couple inches or so. Owens Corning doesnt seem to have a spec on this. Thx.


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## 6stringmason (May 20, 2005)

I would be comfortable with a few inches.


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## 2low4nh (Dec 12, 2010)

I wold add a stud. place some blocking add a stud break the joint problem solved. the only way I wold overhang is if it had sheetrock behind it doing an overlay. then up to 6" over hang should hold up.


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## Tscarborough (Feb 25, 2006)

1/2 the minimum length of stone that will be on it. That is assuming it is flat with no return, if there is a return, then add the stud in the corner.


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## CO762 (Feb 22, 2010)

durock is the hardest CBU, but I'd also definitely check into metal if, as asked, there isn't a return.


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