Do you recommend one or two anchors per base plate?

Does it matter if they are side by side or diagonal from each other?

Number of anchors

The choice and number of anchors belong to the rack design engineer and will be specified in the original Load Application and Rack Configuration drawings (LARCs). The factors involved are:

  • The type of anchors
  • The thickness and size of the footplates
  • The height-to-width ratio of the upright
  • Single-deep, double-deep or back-to-back rack
  • Drive-in rack
  • Seismic zone

In low seismic activity zones, designers typically ask for a single anchor installed through either one of the two holes of the baseplate. This makes some columns prone to twisting when laterally impacted by forklifts. Consult your OEM or an engineer to know if you can safely add an anchor to help prevent twisting of the columns.

Seismic zones

Typical rack designs in low seismic zones ask for a single 1/2" diameter anchors of more than 3" embedment in the concrete slab per rack column. In seismic zones, most design engineers will resort to using different types of anchors (larger diameter or chemical anchors) located on each side of the column and will design a specific baseplate that can withstand greater forces. Sometimes, the OEM will provide four holes per baseplate but LARCs may recommend only putting two seismic anchors. In such case, most installers will anchor diagonally when possible.

Learn more about rack anchors by reading our blog article on the topic.