What Is the Height to Depth Ratio of Shelving Units?

Q: What is the ratio?
A: The ratio for shelving units is typically 4:1. So for every 1’ of depth you can go 4’ wide without using anchors. An example would be if you have an industrial shelving unit that is 87”H x 18”D, divide 87 by 18 to get 4.83. Since that number is over 4, you will need to anchor the unit. 

Q: How does a back-to-back unit impact the ratio? Do the units need to be secured/ tied to each other in a certain way in order for the entire “depth” of the back to back unit count towards the height? 
A: The ratio for back-to-back shelving units is still 4:1. The two units are considered to be one unit as they are bolted together every 16” to 18”. An example here would be, if you have (2) industrial shelving units back-to-back that are each 87”H x 18”D, divide 87 by 36 to get 2.42. Since that number is under 4, you will not need to anchor that unit.

Q: How was the 4:1 ratio determined?
A: Ratios are determined by a number of different factors. It is a comparison between seismic, slab, soil and load factors being compared against size, depth and type of anchor. In most cases, the 4:1 ratio will apply, but it’s always best to talk to your Regional Manager about your exact situation.

Q: Can that ratio be changed if footplates are added? If so, what does that look like? 
A: Footplates do not change the 4:1 ratio for the shelving units. In almost all instances, footplates are used during installation of Borroughs industrial shelving. Typically, Borroughs has standard, two-bolt and three-bolt footplates.  

Q: Does the span between shelf levels impact the ratio? If so, how?
A: Span between shelf levels does not impact the height to depth ratio of the shelving unit.

Q: Is there a way we can increase that ratio? Different size anchoring, etc?  
A: You could increase the gauge of the footplate, increase the diameter and depth of embedment for the anchor, or, most expensively, make your slab thicker.