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Drywall, cement board, or other for uninsulated exterior-facing wall?

Drywall, cement board, or other for uninsulated exterior-facing wall?

Old 12-29-19, 06:52 AM
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Drywall, cement board, or other for uninsulated exterior-facing wall?

The exterior walls of my 1920s-built bungalow have a basic construction of wood siding > framing > shiplap > drywall (added ?). There is no sheathing or wrapping or insulation of any kind. Just empty wall cavities between shiplap and wood siding.
We recently removed the drywall and shiplap from a kitchen wall, corrected some failing wall studs and bottom plates (what a mess...) and were trying to decide what material(s) to use to cover the wall. We want to have some amount of barrier from the elements (heat, moisture, critters in the crawl space). This wall will support base cabinets, sink, dishwasher, floating shelves and a tile backsplash. The other 3 kitchen walls (all interior) and ceiling have shiplap in tact and well hang new drywall.

at first, we thought wed use 1/2 plywood, but Im not convinced that will hold up to the external elements and moisture. It also fails to meet codes for fire resistance. Additionally, I dont think that plywood is the best backing for wall tile.

Drywall, with its paper backing also seems like a no-go against moisture and elements. Ive also been looking at materials like green board, but they seem to have mixed reviews.

so, I was thinking of using cement board (Durock or Hardie backer) on the entire wall. I know that some folks use it in exterior applications and that its designed for tiled and wet areas like showers. Im not sure if well run the backsplash all the way up to the ceiling, but it seems as though cement board can be painted, though not super easily.

thoughts? Any reason I shouldnt use cement board for this application? Other products youd recommend? Thanks!
Old 12-29-19, 07:20 AM
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#1, Did you figure out what caused the wall to fail in the first place and address that?
Is this balloon wall construction?
If so you need to be adding fire blocking.
I for sure would be adding insulation before any finish wall covering.
Since this is just a kitchen I just be using regular 1/2" drywall.
Old 12-29-19, 10:46 AM
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Your heat, moisture, critter problem should be addressed on the exterior of the house, not the interior!
Old 12-30-19, 01:06 PM
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Thanks for your responses!
@joecaption its not balloon framed. (Interesting, I had never heard of that!) All of the framing is sitting on the flooring, which sits on a pier and beam foundation. The wall cavities dont open to the attic either, as theres shiplap covering the ceilings.

The wall didnt totally fail as much as the flooring did thanks to previous water damage and termites. Were treating termites professionally. We also re-leveled the house and added piers when we bought it 6 years ago, so a lot of the existing drywall cracked. We havent noticed much settling or new cracks since and weve patched and painted a few times.

perhaps it would be okay to just use drywall? Im just not sure how much moisture our empty wall cavities are exposed to.

@marq1 totally understand! In an ideal setting, wed have insulation, sheathing, sealed wrapping, and then the siding. However, were trying to frame an 8 x 8 wall for a kitchen refresh and dont really have the appetite to rip off all the wood siding on the house and do it the right way. If we were to do it that, we would probably just scrap the house and rebuild a new one on the site. Ill admit, were putting a bit of lipstick on this old pig, Im just hoping we can find a decent solution for this wall that wont mold over in a year or two.

Is cement board overkill? Any thoughts on Greenboard?
Old 12-30-19, 02:24 PM
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I would just hang mold resistant drywall. (This is not greenboard... it is better than greenboard at resisting mold.) You don't need to use cement board unless it's a wet location (like in a shower).

You will want to consider the thickness of the old door or window jambs, and shim the studs according to your needs. In other words, if the front edge of your door and window jambs are 1" beyond the studs, you would want to shim them with strips of 1/2" plywood before hanging your drywall. If they are 1 1/8" past the studs, shim the studs with 5/8" plywood. You run into this on older houses that used to have lathe and plaster.

If the jambs stick out 1/2" beyond the studs, then all you need is 1/2" drywall. That's normal for modern houses.

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