The most common rack type allowing access to every pallet via standard forklift; lower density but full selectivity.
Detailed Definition
Selective rack, usually meaning single-deep selective pallet rack, stores one pallet deep on each side of an aisle, so a lift truck can reach any pallet without moving another. It is built from upright frames and pairs of horizontal beams, with pallets resting across the beams, often on wire decking or pallet supports. The trade-off is floor space: every rack row needs an aisle in front of it, so it holds fewer pallets per square foot than drive-in or push-back systems.
Single-deep vs double-deep selective rack
Single-deep rack gives direct access to every pallet position and works with counterbalanced forklifts and standard reach trucks. Double-deep rack places two pallets back to back on each side of the aisle, which cuts the number of aisles but needs a deep-reach truck and means the rear pallet is only reachable after the front one is moved. Double-deep is often used when each SKU has at least two pallets on hand.
Matching pallets to frames and beams
A 48 x 40 pallet is normally stored with the 40-inch side facing the aisle, so the 48-inch stringers span front to back across both beams. Frame depth is usually a few inches less than pallet depth so the pallet overhangs each beam slightly; 42-inch frames are common for 48-inch deep pallets. If stringers run parallel to the beams, the pallet is supported only at its ends and needs to be rated for that racked condition or set on decking.
Aisle width and truck choice
The truck sets the aisle. Counterbalanced forklifts need the widest aisles, reach trucks less, and narrow-aisle or turret trucks the least, often with guidance systems. Check the truck manufacturer's right-angle stack figure for your pallet size before fixing the layout.
Related Glossary Terms
Frequently Asked Questions
How much weight can a selective rack level hold?
It depends on the beam size and length, the connector design, and the capacity of the upright frames, which also depends on the vertical distance between beam levels. The manufacturer should provide a rated capacity per beam pair and per frame, usually posted on a load plaque. Rack design in the US generally follows ANSI MH16.1. Never exceed the plaque, and have changes to beam heights reviewed, because they can lower frame capacity.
When is selective rack the wrong choice?
Selective rack wastes space when you hold many pallets of only a few SKUs, because you pay for an aisle in front of every position even though you rarely need random access. In that case drive-in, push-back, pallet flow or block stacking can store more pallets in the same building. Selective rack makes most sense when you have many SKUs with few pallets each and need to reach any pallet quickly.