I have 24 inch center studs 10 ft tall walls. Running 1/2 inch thick 4x8 sheets horizontally. My horizontal seams in between the studs have a lot of flex.

Do I need to add a small 2x4 in between my studs for drywall seams?

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    why wouldn't you go with 4'x10' and have 1/3 as many seams? 4x8 you'll have 2 sheets and a 2' strip somewhere? that's a lot of seams! Nov 14, 2023 at 6:44
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    Installing drywall vertically is much more challenging. Framing is rarely perfect enough to have the joints split the studs nicely. Maybe for one wall, but for larger jobs I'd still go horizontal.
    – isherwood
    Nov 14, 2023 at 13:48
  • can be true though my experience is 10' studs are often finger jointed and straighter than standard dimensional - depends how straight his studs are. Nov 14, 2023 at 17:38
  • @isherwood It depends on who framed the wall. If the person who framed it, is also the person who is going to drywall it and happens to have a firm and everlasting hatred of mudding...
    – Questor
    Nov 14, 2023 at 22:46
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    @isherwood, there's also the ergonomics. Less work by your toes. And I think that sheetrock has a strength axis. 1/2" is only good for 24" framed ceilings if it runs perpendicular to the framing. But maybe that has something to do with the ratio of edge fasteners to field fasteners?
    – popham
    Nov 14, 2023 at 23:06

3 Answers 3


Tape and mud firm up the edges. No need for blocking.

Technically, there's an ASTM for drywall installation. ASTM C840. For single ply installations:

8.2 In single-ply installation, all ends and edges of gypsum board shall occur over framing members or other solid backing except where treated joints occur at right angles to framing or furring members.

The "treated joints" are just taped and mudded joints.


You don't need to. As popham said, the tape joint itself locks things together adequately.

However, it would be very easy to float backing (as opposed to installing blocking). Small scraps of 1/2" plywood (or whatever you have on hand) could be screwed to the first sheet between studs, then to the second sheet. This would tie them together as well. There's no need to fasten to the studs.


For 1/2" drywall, the maximum distance between studs is 16". For 24" o.c. studs, 5/8" drywall is required. This will fix the movement you are experiencing.

  • 2
    ASTM C840 lists 1/2" drywall as adequate for 24" spaced wall studs. It's under Table 2.
    – popham
    Nov 14, 2023 at 6:48
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    1/2" drywall is even approved for ceilings on 24" centers these days, assuming it's of the no-sag variety. Also, 5/8" would require larger door jambs, etc.
    – isherwood
    Nov 14, 2023 at 13:49

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