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I am in the middle of building a complex storage rack system in my garage. I ran 2x4 "sleepers" across the ceiling and tied into every floor joist. My shelving system is anchored to this.

Here is where it gets interesting. I did not think twice about this design because I assumed I was anchoring into 2x8 or 2x10 floor joists (room above garage) but when I cut a hole in the drywall to relocate a light fixture, I found I was tied into 2x4's. Basically I have 2 sets of joists. 2x10's above, then about 6 inches down, the 2x4's, 16" OC holding up the sheetrock.

The dimensions of the garage are about 20x20, but there is a beam in the middle shortening the span of said joists to 12ft. Has anyone ever seen/heard of this before? I can't understand what the reason for this design would be, other than the extra insulation that is in this space (im in Canada).

I am thinking of rather than ripping the shelves out and starting over, strengthening the 2x4's by tying into the 2x10's. Thoughts?

  • Any chance you can post some pictures? – UnhandledExcepSean Sep 6 '18 at 17:36
  • What kind of load does the shelving system impose on the 2x4's? Unless the shelving is suspended from them without touching the floor, they might be strong enough to help support the shelves. – batsplatsterson Sep 6 '18 at 18:45
  • Can't figure out how to upload pictures to this site. The shelving is not supported from the floor. My initial thought was to use something like this anchor from the 2x10s to the 2x4s. If I anchored twice along the 12ft span I would theoretically reduce the 2x4 joist span to 4ft. Some loading charts I have looked at suggest 2x4's are too weak to use as joists in any scenario homedepot.ca/en/home/p.18-inch-medium-strap-tie.1000170512.html – Connor Brown Sep 6 '18 at 19:22
  • @ConnorBrown -- upload the pics to imgur and then post a link in the comments – ThreePhaseEel Sep 6 '18 at 23:00
  • WRT the 2x4 sleeper attached to the ceiling, how it that attached to the 2x4 ceiling joists? If they are screwed in from the bottom, I wouldn't trust it to hold the load irregardless of the size of the joists. I'd trust a threaded rod or sheer loaded bolt or structural screws. Yes, I'd go up the 2X10s. – Gary Bak Sep 7 '18 at 11:54
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You ask, “Has anyone heard of this before?” Sure and it seems very logical to me. They are using the lumber where it’s needed most: the bigger joists to support the heavier snow loads and the smaller ceiling joists to support the lighter ceiling finish. Also, the deflection from the snow will not affect (crack) the ceiling finish because the structural systems operate independently of each other.

Now, you want to change that. You’re going to tie the two structural systems together AND add a superimposed load. Hmmm...

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