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Tongue-and-groove plywood wall sheathing?

lance_p | Posted in Energy Efficiency and Durability on

So I’m contemplating the use of plywood exterior wall sheathing.  Having handled truckloads of plywood in a previous life, I’m well aware that 1/2″ plywood can be less than flat, and ordinary spruce ply can be full of voids and imperfections.

So if I use plywood to sheathe my walls it will likely be 5/8″ thick.  T&G is usually the same price as standard square edge.  For exterior sheathing is there a preference one way or the other?  T&G looks attractive since it would be easy to stack the sheets.

Typically there’s a 1/8″ gap left between exterior sheathing sheets for expansion.  Would this be an issue if using T&G locked together?  Also, plywood is usually a full 48″ x 96″.  Having 1/8″ gaps adding up on longer walls could shift the sheet edges away from stud centers.

Am I worried about nothing here, or are these common practices?  Is trimming 1/8″ from each sheet necessary?  The back wall of the house is almost 60′ long.

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  1. Expert Member
    Akos | | #1


    You can use T&G but only if you go perpendicular to your studs otherwise the joints don't fall onto studs. With square edge, you can put the sheets in either orientation. I've used T&G plywood for interior walls, the hard part is hammering them together to get the joint nice and even.

    For exterior walls, square edge is simpler.

  2. Expert Member


    Even at 24" oc. 1/2" plywood loses any of it's waviness once it is secured to the framing. The exterior grade plywood and OSB sold for sheathing already is 1/8" short of 8 ft. It's typically only cabinet grade sheets that are full, or oversized.

    There is some case for using t&g as roof sheathing (although even at 24"oc. 1/2" can be used without H-clips), but there are no lateral p0int loads on walls, so there is really no advantage.

  3. lance_p | | #3

    Thanks for the replies! I had read them a while back and gotten distracted before responding.

    Akos, yes, the plan would be to use the sheets perpendicular to the studs. Hammering the sheets together definitely could be a challenge.

    Malcolm, thanks for that info! Good to know the sheets are already sized that way. Funny, I delivered dozens of houses worth of material in a previous life but never thought about the actual size of the panels.

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