Building a warehouse can be painstaking. The Rack Manufacturer Institute simplifies the process.

“Overloaded beams can bring your operation to a halt. Learn how to keep your employees safe while maximizing warehouse productivity.”


Beam Deflection Basics


As companies maximize the storage potential in their warehouse, overloaded systems are a common concern. During warehouse inspections, our engineers regularly identify deflected beams that pose a risk to the safety of employees and products.


When does a deflected beam become a hazard?


The standard industry formula for determining an overloaded beam is calculated by taking the beam’s length and dividing it by 180. For example, a 96” beam’s maximum deflection should not exceed .53”.


Why should this be a concern for my business?

  • Adequately installed beams with proper safety locks are designed to deflect when loaded. Too much deflection can compromise the integrity of the beam and creates unnecessary risk.
  • When overloaded beams and subsequent deflections exceed industry standards, pallets begin to sink towards the center of the beam, leading to material failure and injury to forklift operators during pallet placement and removal.

What can I do to prevent beam deflection?

  • Regular safety inspections ensure proper oversight and compliance with industry racking standards.
  • Current engineering calculations and load capacity signs help employees better understand the system’s limits.
  • Educating employees on appropriate rack capacity and use of each level is critical to maximizing the system while keeping safety a priority.

How can we maintain compliance between inspections?

  • Beams are designed to deflect when loaded, but it’s essential to understand when the deflection becomes dangerous. Below is a quick method of spot-checking deflection.
  • Deflection spot-check:
        1. Measure beam’s length and divide by 180 to determine the maximum limit
        2. Attach a string from one connector to another along the bottom of the beam
        3. Measure the distance from the taut string to the bottom of the beam
        4. Identify any beams that deflect or are close to deflecting more than the recommended amount

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How much deflection is acceptable?


At normal design working loads, beams are typically designed to accommodate vertical deflections that do not exceed 1/180 (or 0.55 percent) of the horizontal beam length as measured with respect to the ends of the beams. Some users may specify a lesser-deflection requirement for visual appearance or cosmetic purposes. Still, other users with systems intended to use more precise automated storage and retrieval equipment may specify a lesser-deflection requirement. (See ANSI/RMI Specification section 5.3, Commentary section 5.3).