My dad’s words “Build it sturdy!” led me to run my seven 2×4 uprights to pressure treated sleepers on the floor. My barn was built with advanced framing techniques, so the wall studs are 2x6s on 24 inch centers, covered with 5/8 inch OSB. I used short brackets to reduce their moment arm length, and to accommodate the typical lumber I use, which is seldom over 8 inches in width. The brackets are designed with plywood and 2×6 lumber to increase the contact area with the uprights.
This project used shop-grade plywood, dimensioned lumber (pressure treated for contact with the concrete floor), and lots and lots of PVA glue and screws. To fasten the uprights through the OSB sheathing into the wall studs, I used four 6-inch FastenMaster HeadLOK structural wood screws through predrilled and counterbored clearance holes in each upright. These fasteners were really easy to use, and are advertised to be replacements for 3/8-inch lag screws … but they’re not cheap!
Once I had the uprights fastened to the wall, I stretched a line at each shelf level as a guide, so all the bracket tops were in a nice plane. The plywood bracket sides are about 1/4-inch short on the wall side, so I could make sure that the 2×6 cores were in really good contact with the uprights. I added a row of metal shelf brackets near the top of the uprights, for the lighter materials I’d be willing to use a stepladder to store and retrieve.