I am in the middle of building a complex storage rack system in my garage. I ran 2×4 "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 2×8 or 2×10 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 2×4's. Basically I have 2 sets of joists. 2×10's above, then about 6 inches down, the 2×4's, 16" OC holding up the sheetrock.
The dimensions of the garage are about 20×20, 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 2×4's by tying into the 2×10's. Thoughts?
Best Answer
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...