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Hazard Alert: Lateral Supports for Open Web Steel Joists

Construction worker on a steel erection construction site


The Occupational Safety and Health Administration has determined that some of the most serious risks facing ironworkers are those encountered during the erection of open web steel joists.  From January 1984 to December 1990, more than half of the 40 fatalities suffered by ironworkers was related to the erection of steel joists. 

March 1999: Two employees were attempting to realign two open web steel joists that were forced out of alignment when a load of metal roof decking was placed on top of the joists. None of the joists were bridged, supported or restrained against movement.  One employee was standing on a ladder underneath one of the joists trying to pull it into position.  The other employee was standing on top of the decking, pushing on the joist.   Suddenly, one of the joists fell over and collapsed.  The joist, the stack of roof decking and the employee standing on the stack fell 20 feet to the ground below.  Unhurt, the employee ran out from under the other two joists moments before they fell over and collapsed on top of the first joist. Neither employee was injured.  

September 1999: Three employees were using a crane to unload stacks of metal roof decking onto open web steel joists.  The joists were not bridged, supported or restrained against movement.  After the load was set down on the joists, the employees began to release the slings.  After the first sling was released, the load shifted and one of the joists fell over.  This caused the joist to collapse and fall 40 feet to the ground.  One of the employees was tied off to this joist, and he was pulled off the roof.  Two other joists rolled over and collapsed, landing on the employee.  The employee suffered severe head injuries but survived.

The Hazard 

Joist manufacturers require that the ends of joists be tack welded or bolted immediately after placement.  This welding or bolting only serves to hold the joist in place until the bridging is installed, and as a result the joist has very little lateral stability.  Placing any weight on the joist other than the weight of the employee actually erecting the joists can cause the joist to roll over or slip.

If the joist slips, it can:

  • Throw employees off the joist or supporting girder/wall
  • Throw materials and equipment to the ground below
  • Cause a joist to fall over and collapse 
  • Trigger a domino effect and cause other joists to slip

If the joist falls over, it can collapse or buckle.  This can:

  • Throw employees off the joist or supporting girder/wall
  • Drag employees to the ground if they anchor their fall protection to the joist 
  • Throw materials and equipment to the ground
  • Trigger a domino effect and cause other joists to fall over, collapse and fall to the ground

Employees on the elevated work areas could:

  • Fall or be dragged from elevated work areas to the ground below
  • Be injured if materials and equipment placed on the joists strike them. 

Employees working under or near the elevated work could:

  • Be injured if falling materials and equipment strike them.


During construction: 

  • Follow the rules for steel erection in WAC 296-155-701, Safety Standards for Construction.  These rules apply to bridging open web steel joists and placing construction loads on joists that do not have bridging installed.
  • Do not allow loads of any kind to be placed on open web steel joists before the joists have been bridged.  This includes staging construction loads, hoisting equipment and roofing materials and decking.  The weight of the person erecting the joist is the only load to be on the joist until it is fully bridged. 
  • Follow instructions for bridging open web steel joists.  Steel joist manufacturers, building plans and erection manuals prohibit working on open web steel joists until the joists have been completely bridged. The Steel Joist Institute Technical Digest #9 has specific instructions for bridging open web steel joists (address below).
  • Do not allow employees to tie off to unbridged open web steel joists. 

OSHA is adopting new regulations for erecting open web steel joists.  These new regulations will be similar to the procedures in the Steel Joist Institute Technical Digest #9.

Information Sources 

Steel Joist Institute Technical Digest #9
Handling and Erection of Steel Joists and Joist Girders
3127 10th Avenue North Extension
Myrtle Beach, SC 29577-6760
(843) 626-1995

The Steel Joist Institute is an organization of joist manufacturers, and the information in this Technical Digest is considered to be manufacturer's instructions for working with open web steel joists. 

Contact the Department 

For more information or assistance, contact a Labor & Industries' consultant in your area .


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