Grab bar backer board with Sterling Surround?

[ubersanger]

In my addition project, we are going to use a Sterling shower surround for the shower. I know they sell versions with pre-installed backer board for grab bar installation. However, no one carries those versions in-stock locally and the price premium is $300 which seems ridiculous to me. I'd rather get something in stock local as those surrounds are notorious for damage in shipping and I'd rather inspect before buying and not risk project delays.

My question is that since I will do backer board myself, what should I use? The surrounds limit location of grab bar installation. Would 3/4" plywood be good in this application? The tech specs of the surround with the pre-installed backer board are here and do indicate location of the backer board so that I can use that as a guide:
https://resources.kohler.com/plumbing/sterling/pdf/72230106_spec.pdf

The surround is direct to stud install so really it's finding a material that will fill in the space between surround wall and studs at the grab bar location. 2x6 will be too thick.

 

[Jadnashua]

I'd put blocking between the studs, and measure the distance between the surround's wall and the studs. You should be able to stack some plywood the right height, or maybe find a woodworking friend to plane down a solid piece the needed thickness.

 

[Sponsor]

 

[Terry]

It looks like the backing would be flush with the framed walls. Whatever it takes there depending on where your wall studs are now.

 

[ubersanger]

So once I get it in place, figure out how much room is there and fill as needed. So plywood is ok to use as the fill as long as I've got something solid behind it. Correct?

 

[LLigetfa]

Would 3/4" plywood be good in this application?

I find that OSB holds screws better than plywood. That said, I would use wood blocking between the studs.

 

[WorthFlorida]

I had blocking done for future grab bars if ever needed. 2x4" were used. My house has a mix of wood and steel studs. If you use plywood, sandwich 2 3/4" boards. Look at the installation instruction for the grab bar. Most will have 2" screws.

 

[Jadnashua]

With solid blocking between the studs, the ply or whatever you use to fill in between the wall of the surround and the plane of the studs is essentially just a filler. I'd use a 2x6 or 2x8 blocking and screw it into the studs (maybe even some construction adhesive, too) to anchor them well. Then, the ply or whatever is just there so when you tighten things down, it doesn't bow in.