Pallet Racking Bay Starters vs Add On Units: Key Differences (Video)

In this video, we clarify the difference between pallet racking bays ("starters") and add-on units ("adders") for shelving, pallet racks, and cantilever rack systems, to help you decide what's right for your needs.

What's the Difference?

In a general sense, a "starter" is best described as a complete section that is intended for use as a stand-alone section, or the first bay in a continuous run. An "adder" is not a complete section and must be connected to either a starter or another adder.

Image of a selective pallet rack starter section and adder section. — Starter on the left, adder on the right

For example, building a run of two connected pallet rack bays requires one starter and one adder, but building two separate pallet rack bays require two starters. The difference between starters and adders when it comes to selective pallet rack is with the uprights, as both will have the same number of beams and wire deck.

Starter & Adder Pallet Rack Bays

Starter bays have two uprights, while adder bays only have one upright. The side of the adder bay without an upright is able to connect to a starter bay or another adder bay to build a continuous run.

Teardrop rack starter section and adder section.

Use with Cantilever Racks

When looking at cantilever rack, the difference between starters and adders is only with the towers. Both will have the same bracing and arms, but the starter will have two towers and the adder will only have one tower. Just like with pallet rack, the open side of a cantilever bay will have to be connected to a starter or adder to build a continuous run.

Cantilever rack starter section and adder section

Use with Shelving

The same pattern is true for boltless rivet shelving and warehouse shelving. Both boltless rivet shelving and metal-clip shelving use posts on each corner instead of uprights or towers. A starter will have posts for all four corners while an adder will have two posts, and open on the other side.

Industrial metal shelving starter section and adder section.

These shelves use posts on all four corners instead of uprights. A starter unit will have four posts while an outer unit will have two posts. Adders need to be connected to either a starter or another adder to build continuous runs, and starters are the only ones that can stand alone.