Concrete Backer Board, Cold Climate

[pecker88]

I know that PermaBase concrete backer board is rated for outdoor use. But, I can't find many details about cold climates. For 6 months here it's freezing/thawing sometimes daily.
My plan is 20-ga steel studs, 16" OC, cover it with 1/2" PermaBase, trowel on RedGard waterproofing membrane, then finish with stone.

I've done this before in Arizona, but here in Nebraska, not sure it would hold up.

The other option is Concrete block and forego the metal studs. I really dont' want to lug a pallet(s) of concrete blocks though..

thanks!

[RandyJ]

When I did mine I used 18 gage studs. They are a lot stiffer than the 20. You can easily bend the 20 gage with your hands but you might break your knee trying to bend the 18. As for the cement board that is what I did then taped and trowel with thinset. You can do the red guard if you want but shouldn't need to if you will be doing the stone right away. My oven has been doing just fine after 3 winters here in MN and a few pretty nasty storms.

Randy

[pecker88]

Thanks for the insight. My kitchen island and oven will go against a retaining wall, so the back won't be finished. I was thinking block for the back wall would stand up to weather better then exposed concrete board. But, after starting the design with concrete block, I'm quickly realizing it's not as easy to frame in openings for cabinet doors, drop-in grill, ect... compared to using steel studs.

Maybe I'll build the back wall out of concrete block, then the rest will be 18-ga. steel studs and concrete board.

[UtahBeehiver]

If you are concerned about the exposure of a concrete backer board butting up against the retaining wall then look at James Hardie HZ5 siding panel for this area. The HZ5s are made for freezing temps, can be bought prepainted or you can paint to match you needs. Good for Zone 1-5 or basically the northern half of the US.

[RandyJ]

One other option for the back wall would be to go with stucco to give the cement board a protective layer. It would not have to be super pretty just there to keep the water out. It might be a good idea to do the red guard on that side as a extra protection from water.

Randy

[pecker88]

Thanks guys. The wall starts at 10 ft tall, then steps down to 4 ft or so, about 25 ft long.

I want some space between the kitchen isl. and the wall so they can move independently. Foundation under the island will be 12" deep, by 12" wide around the perimeter. That's code for a floating slab here.
A 3" separation b/t wall and island at the bottom, means the top of the island will have about a 1 ft. space between the wall. This is b/c the wall slopes backward, like all retaining walls.

With only a few inches of space at the bottom, there would be no way to finish the back of the island. If I push the island any further away from the wall, it will start blocking the patio sliding glass door, so I'm really b/t a rock and hard place here.

So, stucco, siding or stone finish on the back would be difficult with such a tight working area. Hence, my idea for block, then just letting it exposed indefinitely.