I wanted to screw Hardie backer board (.42") over my drywall to the steel studs to adhere 6" x 24" x1" stone ledger panels using polymer modified thin-set, floor to ceiling is 12'.
Problem is that Hardie and Durock backer board specifies 16" maximum (assuming no drywall is underneath). Problem I guess is deflection (bowing). Does anyone have any recommended practice with this kind of application?
I feel that adding construction adhesive in between the drywall and backer board along with screws to the studs should strengthen it quite a bit. Plus the ledger panels will add rigidity.
Adding 2x4' studs is not an option for me.
Thanks for your help!