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Structural Sheathing a “Good Enough for Now” Garage

jenniferz5 | Posted in General Questions on

In Zone 5a CT, I have a 60 yo garage that I would like to turn into a workshop/workout room/hang-about for the kids.  At one time it was leaning (due to the wet ground on one side), but previous owners filled the concrete block foundation with cement and rebar and (I think) added structural beams to the ceiling.  It is mostly level (one side is a smidge off).  

Since I have some leftover ComfortBoard from another project, my idea is to do this:
1. Use two-part epoxy to fill any gaps and repair a few spots of rotten wood (minimal).
2. Fill stud bays with the ComfortBoard.
3. Attach plywood to the studs (over the Comfortboard) as structural sheathing.
4. Paint it all (including plywood and concrete block) with Caliwel mold and mildew inhibitor (also have some of this left over), add some Flow Walls for storage, call it a day.
4a.  I *might* add some rubber flooring to the exposed concrete, if we do use it as a workout space/hang-about.

Will the plywood work as additional bracing for the garage?  Should I do anything else/additionally?

Thank you!

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  1. charlie_sullivan | | #1

    That plan generally seems fine, but what is on the outside of the studs now? No sheathing and just some kind of siding? What about a ceiling? Is there one?

    Also, it's a little bit of a shame to use the more expensive comfortboard where less expensive batts would do, so if you can find somewhere to sell or donate the extra comfortboard and buy some batts that might make sense.

  2. jenniferz5 | | #2

    The garage has a horizontal siding with a bit of a bevel on the long ends. This is attached directly to the studs. There is a "ceiling" - it is the underside of the roof. I'm not sure what I'll do about that, as we do use it for storage and it IS a garage. If I can figure out storage for whatever is up there (on plywood sheets) I will do the same to the ceiling as I plan to do to the walls.

  3. Expert Member
    BILL WICHERS | | #3

    Yes, adding plywood across the studs adds bracing and a lot of stregth for racking resistance. Ideally you want to install structural sheathing like this so that it lands on not only the studs, but also the top AND bottom plate for EACH sheet of plywood. This way the sheathing ties the entire wall assembly together -- top plate, bottom plate, and studs in between. This will get you a strong wall.

    Way back in the day (way, way back), I was building a set on a stage, and we had a similar leaning issue to what you had. The solution was to jack things back square using tensioned diagonal cables, then put up plywood in the way I just described. Once the plywood was up, the cables were removed, and the structure stayed solid and square. Theatrical stuff is often built in ways that would make building inspectors run away in terror, so I'd generally recommend against building anything stage-style, but in this particular case, it is a good example.

    I don't see any other issues with your plans. If you're planning on conditioning the space you might want to do some extra detailing, but if this is just a slightly beefed up garage you should be OK.

    BTW, the interlocking rubber tiles often use for exercise room floors can be an easy and relatively cheap way to put a floor in a room like this. You might want to look into those.


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