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I'm having countertops installed and the top cap of pony wall is two stacked 2x4s with the wood outer edge flush with the drywall. My first thought was just to prime the wood and use joint compound and tape to fill the gaps then skim coat to blend. But there is concern that wood movement will cause cracks.

Is there a better material to cover the wood with that is more forgiving?

The end of the studs had drywall material on it for 18 years and never cracked or separated. I would prefer to not use a trim board which is what they had done in the past. One drywall guy wont touch it unless I cut back the studs 1/4" from the face so he can install 1/4" drywall in a butt joint. Photo of Pony Wall

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  • Thank you for all the input. Since the countertop folks were coming the next day I didn't want to delay the installation if I didn't need to. However, I finally just went for it and removed the two top caps and ripped them down 1/4 inch and then screwed them back in place. Then a piece of 1/4" drywall could be added to make the butt joint. Since this is in Arizona with A/C I'm hoping wood movement will be minimal and this will work fine.
    – Xylocarpus
    May 14, 2022 at 18:05

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Your drywall guy is correct, from a "guaranteed not to crack" perspective. If the timber is old, you might get away with it, but from a professional installers point of view "might" just isn't going to cut it.

In relation to the whole job this is a tiny issue, why not just do it properly? Also I note that there looks to be a radius on the corners, how did you propose to deal with that on the timber?

If it were mine, I'd get a blade in there and cut the nails, refit a smaller top timber, remove the lower drywall and add new drywall to the whole back, removing the joint altogether.

Or if space allows, just add drywall on top of the old, but the radiused corners are going to be an issue to resolve either way.

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  • You clad it in drywall, but the seam between the old and new drywall is still there. If the wood is going to expand and contract significantly after 20 years, drywall isn’t going to behave any differently than compound.
    – RibaldEddie
    May 11, 2022 at 6:16
  • Yes, but it could be argued that a butt joint is a normal situation, and within limits all timber moves underneath drywall, flexing slightly on the fasteners. Applying compound directly on timber is something I've never seen in nearly 40 years as a contractor. Plus I should have been more clear. I'll edit my comment to show that I meant to clad the whole thing with drywall. No more joint :-)
    – handyman
    May 11, 2022 at 7:10
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This should be fine to just cover with compound, but do not use ordinary joint compound; i.e., the compound that comes premixed. You should use something at least as hard as setting-type compound. Setting type compound comes as a powder and must be mixed with water immediately before use. Setting-type compound gets hard from an exothermic chemical reaction just like cement. Pre-mixed compound that comes wet gets hard just from drying out.

Look for setting-type compound that says it can be used as a concrete filler. That will dry rock-hard and is much less likely to crack.

You could even embed fiberglass-reinforced drywall paper in the fast setting compound between the seam of the two pieces of lumber.

If for some reason you really don't want to just put compound on the dimensional lumber, you could attach 1/8 inch luan plywood to the lumber and then feather the joint compound down the front of the wall. Adding 1/8" of thickness shouldn't really make a difference but you will need to feather a decent amount of compound to make it look flat.

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    Your assumption that "rock hard" meaning it won't crack are not correct. In fact, material which is immovable is more likely to crack, in these situations materials able to absorb some movement are a better choice.
    – handyman
    May 11, 2022 at 5:56
  • @handyman like those brick walls made with a lime based cement that have curved with age while the newer cement makes the walls crack...
    – Solar Mike
    May 11, 2022 at 6:10
  • @handyman strong disagree. By this logic, on drywall itself it would be bad to use harder joint compounds. However the opposite is true. Stronger, harder joints are preferred. The framing onto which gypsum panels are fastened often have significant more movement than this 20 year old countertop base, yet setting type compound provides superior crack-resistance.
    – RibaldEddie
    May 11, 2022 at 6:10
  • @RibaldEddie not at all, hard compound is great between the same material. It was that you were implying that using a hard compound would be strong enough not to crack in this situation and that isn't true, no compound is strong enough to resist such a differential in material (i.e. wood and drywall), their differing thermal expansions are just too different.
    – handyman
    May 11, 2022 at 7:14
  • @Solar Mike Exactly. Lime mortars are awesome, hairline cracks will even 'self repair' to a small degree, with the slight thermal movements grinding the mortar into the crack if you like.
    – handyman
    May 11, 2022 at 7:17

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