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I'm building a freestanding "wall" in my garage, for storage.

free standing wall, partially completed
Click any image to embiggen

It's obviously incomplete in the photo (it's also only temporarily floating off the ground). I'll be adding a 2x4 along the top, plywood along the "floor" on both sides of the wall, and some plywood on the vertical wall itself (only on one side).

As far what's there already, the floor is just 2x4's (Doug Fir) and deck screws. The "wall" studs are held to the floor with these straps (they're on the back of each stud too too, not visible in photo) and thru 1/2" stainless bolts/nuts/washers. The wall is 7' tall. The floor is 6' wide.

On one side of the wall, I'll have several bikes mounted (like this:

bikes mounted on wall rack

I expect to have up to 10 bikes at 30 pounds each to be conservative, so 300lbs. That side of the wall will get plywood, which I think will provide enough cross bracing in the plane of the wall. Any references to "cross bracing" below are referring to the plane of the T.

On the other side, there will be a 100lb kayak sitting directly on the "floor". And surfboards mounted higher up the wall like this. Their weight will be pretty minimal and is not much of a concern.

surfboard rack

In terms of physical space, I'd love to have no cross bracing, but obviously that is out of the question. I know that the T will need cross bracing of some kind, and my main question is exactly how to go about that. I don't know much about wood construction, only that having members in compression is ideal. Which would imply cross bracing on both sides of the wall. But... it's probably out of the question to have cross bracing on the kayak side (since the kayak will take up the entire floor, plus some overhang on both ends, interfering with the space where any cross braces would go).

Assuming I put diagonal cross bracing on the bike side only, I'm trying to decide:

  • how many cross braces to add
  • how long they need to be
    • all the way from outboard tip of floor to highest point of wall?
    • just 3' base/height 45-deg, from tip of floor to almost halfway up the wall?
    • 45-deg but shorter than 3'? (shorter interferes less with bike space, but may not provide enough support)
  • exactly how I attach them to the wall and floor (this one I'm especially concerned about, since the cross braces will likely carry some tension for the loads on the non-bike side of the wall)
    • lag bolts? (braces in line with studs)
    • thru bolts? (braces offset from studs)
    • some sort of metal hanger/strap like I used in the T joint?

To make matters even more tricky, there is a chance that the non-bike side of the wall will one day have a not-insignificant load on it. I might want to have a cantilevered 3ft shelf coming out about 2ft high (so basically the floor under the kayak, projected upward 2ft), on which I would store another 100lb kayak. I'm not sure that a cantilevered shelf like this would even be possible (both in terms of the shelf's attachment to the wall, and in terms of stressing the T-joint with no compression cross bracing on the kayak side). It would be a 100lb load centered 18" outboard of the wall. If it is possible though, I'll want the T cross bracing solution determined above to account for that eventual load.

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    Wood is fine in tension (see a few billion wooden roof trusses), though if you are planning on a "tension only" brace you can use a lot less steel than wood to get there.
    – Ecnerwal
    Commented Apr 17, 2022 at 18:00
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    Unless it's a weird sort of kayak, there will be room for small braces due to the shape of the hull. Even a small brace is better than no brace.
    – Ecnerwal
    Commented Apr 17, 2022 at 18:10
  • @Ecnerwal regarding both "small brace" and "tension only steel", if I added these at both side of every T-junction, do you think that alone could completely solve my cross bracing dilemma? I'd expect them to act in tension for loads on either side of the wall. But I don't know if I'd need to worry about (a) lag screw pullout or (b) the 7ft wall beams bending.
    – The111
    Commented Apr 17, 2022 at 18:21
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    Looking to the future, I'd consider putting castors on, to be able to shift it wherever, if the floor is level.
    – Tim
    Commented Apr 18, 2022 at 11:30

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OK- I did these drawings just for weekend fun. This is not at all engineered except from my own experience working with wood framing.

I would double the top plate to help prevent the wall bending- it seems those bike hangers will put some pull on the wall from up high where they hang- so I also like the braces going all the way to the top.

The kayak side is fairly simple. You definitely need the 45º braces to keep from having side to side movement. 2 x 4 will easily span 4' or 5' with a 100 pound kayak and even you standing on top of it.

enter image description here

enter image description here

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  • Thanks, that is awesome! What did you use to model that? I was a mech eng for a decade and used Pro/E and Catia regularly, but it's been a long time and I've forgotten those skills. I also dealt with metals in my work (hence my wooden ignorance). For the attachments on the bike side diagonals, you just recommend lag bolts screwed through both pieces? Maybe 1/4" bolts something like 6" long (assuming I screw it normal to the diagonal piece)? And for the kayak side shelf... is there any way to make that work as a pure cantilever? Guessing not... but curious.
    – The111
    Commented Apr 18, 2022 at 6:06
  • I am just learning Vectorworks (no affiliation)- it is a 3d/ architectural program- very powerful. It was a fun project (done quickly) for me waking up this morning. I would use 1/4" x 5" or 6" lags (recommend simpson SDS screws) through the diagonal braces into the floor structure and the top plates. I don't see any way to do a full cantilever for the kayak unless it was some kind of fairly heavy metal L bracket- probably something you would need fabricated and not available off the shelf. Good luck- it looks like a fun project that will be very cool once it is done.
    – Kyle
    Commented Apr 18, 2022 at 7:43
  • That looked to me like SketchUp (you can use the current version on the web, or find the older, download/install version, both free, I think) to me. I'd suggest making the platform big enough to slide the kayak underneath it, the put the surfboard rack above. Simple decking screws should be enough, lag bolts would be more than enough. I had a rack storing 8-10 4x8' sheets of plywood and other life-detritus put together with mostly drywall screws. Not recommended, but it held up for 25+ years.
    – FreeMan
    Commented Apr 18, 2022 at 13:29
  • @Kyle though you might enjoy this update half a year later. Yeah, I'm slow. Actually finished most of it a long time ago, but just added the second kayak shelf a few days ago since we finally bought the second Hobie. Two images: image one | image two. Thanks again for your advice! The whole thing is super sturdy. Maybe about 500lbs total between bikes and boats, but I overengineered it and used way heavier fasteners than needed. It could probably hold a lot more if it needed to.
    – The111
    Commented Oct 9, 2022 at 5:50

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