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I am building a room in the garage and I went ahead and bought 8' 2X4s but now after measuring the ceiling height (noob), even with a double top plate, I am still half an inch short.

What is the best practice here? Are there shims for this situation? Most I see are for doors and windows. I was thinking I could put half-inch shims under each stud between the plates.

isherwood
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Anthony DeFreitas
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  • As it stands, you're asking two different questions. If you'll take the [tour], you'll see that this site operates on a "one question per post" philosophy. Please [edit] your question to ask about the "shim" situation only, then ask the rest about the rafters and nailing it to the wall in a separate question. – FreeMan Nov 16 '22 at 00:52
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    ...And put pictures in that question, because it's unclear in the extreme how a wall with a top plate "only has 3 places to nail to" due to rafter spacing. – Ecnerwal Nov 16 '22 at 00:53
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    As to the lack of nailing locations, are you running the new wall parallel to the ceiling joists? If so, the typical solution is to install blocking between the joists so there's something solid to attach the wall to. Pictures might help here. – spuck Nov 16 '22 at 00:53
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    Don’t forget PT for the bottom plate. – Aloysius Defenestrate Nov 16 '22 at 15:04

3 Answers3

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The "shim" you're looking for is called "a sheet of 1/2" plywood". You can rip it into 3-1/2" wide strips and add it between the doubled top plates.

Please note that "1/2 inch" plywood is usually not exactly 0.500 inches thick. Usually it will be somewhere around 0.400 - 0.520 inches. You will have to look at the specific stacks of sheet goods at the store you're buying from to see what they have in stock. You may consider going to more than one store to get something that will fit correctly for the precise gap you've got.

FreeMan
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Height-wise, 1/2" plywood under the bottom plate or between the doubled top plate would be better than a shim directly under each stud. Doing it the way you suggest would make the joints very weak.

Ecnerwal
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    If going under the bottom plate, use pressure-treated plywood since since cement garage floors have a tendency to be wet sometimes. – spuck Nov 16 '22 at 00:55
  • I believe that experience shows that non-pressure-treated lumber on the basement floor somehow directly causes flooding... Nobody quite knows how that works, but it seems to always happen. – Jon Custer Nov 17 '22 at 20:38
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If you have the timber available, tripling up the whole top or bottom plate would be another solution.

This is not little pieces of shim, this would be a third layer of wood at the top or bottom of your wall. Essentially you're making a 3 layer top/bottom plate not 2 layers.

You could buy longer studs and return the ones you already bought, but the shop might not accept them specially if they've been cut to length. Or put the short ones aside to use for nogs/dwangs and buy more studs the right length.

Criggie
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    "tripling the top or bottom plate" is exactly what both Ecnerwal & I suggested. Rebuilding the wall by cutting the studs 1/2" longer is certainly a viable, though expensive, option. – FreeMan Nov 17 '22 at 12:12