Stone veneer substrate
What would be the drawback(s) from using cement backerboard for the substrate on a manufactured stone veneer , using portland and sand for mortar, instead of a standard scratchcoat with expanded metal lath? I understand that portland and sand is the best mortar. The veneer would be applied as basically a dry stack configuration ( very slight joints). This is an exterior, south facing wall, with a six-foot overhang in northern Illinois. Go Cubs 🙁
Even manufactured stone is moderately heavy so I like the substrate to offer some "bite" for the mortar. So, even if I use backer board for a substrate (and I have), I always nail on self-furring metal lath (nailed through the CBU to the framing, or even the sheathing if it's plywood and not OSB), trowel on a scratch coat and comb it.
I suppose backer board might be OK for a mf'd stone that was like a shale, but if you're doing a "drystack" appearance, like a ledgestone, you have to treat it almost like the real stuff....in fact, with that stuff, I sometimes even use some metal masonry straps at times, to hold it in place while the mortar sets, or if a particular piece has some excessive overhang.
Go Cardinals :-)
Edited 8/4/2006 4:19 pm by Notchman