OSHA Load Requirements

Scaffolding and scaffold board load requirements are governed by OSHA 1926 Subpart L. OSHA has provided a non-mandatory Appendix A to help contractors comply with the requirements of Subpart L. This appendix contains the following chart:

_______________________________________________
              |                |
  Maximum     |   Maximum      |    Maximum
 intended     | permissible    |  permissible
  nominal     |  span using    |  span using
   load       | full thickness |    nominal
 (lb/ft(2))   |   undressed    |   thickness
              |  lumber (ft)   |  lumber (ft)
______________|________________|_______________
              |                |
25............|           10   |       8
50............|            8   |       6
75............|            6   |
______________|________________|_______________

According to the Appendix, using the typical 7’ span between the frames with the 2X10 nominal thickness lumber will not achieve the 50 pounds/square foot rating in terms of board capacity. The maximum allowable span between the frames with this type of board is 6’. Here is another link to an OSHA workbook with this information: http://www.osha.gov/SLTC/etools/scaffolding/planking.html.

Does this create a problem medium-duty contractors using 7′ spans? Not necessarily. Appendix A is a guideline and not mandatory. The mandatory rule is found in OSHA 1926.451(f)(16) and says a scaffold board cannot deflect more than 1/60th of its length when loaded. This means a board on a 7′ span can deflect up to 1.4″ when fully loaded.

Some scaffolding companies, including Southwest Scaffolding, sell boards that are DI-65 #1 pine, which will deflect less that the 1/60th of the span as required by OSHA when under the stress of a medium-duty load. These boards are tested by an independent agency, and stamped. As long at the boards deflect 1.4″ or less when you are working on them, they are OSHA compliant.

OSHA’s deflection limitation makes a good case for using OSHA tested scaffolding board or manufactured boards/platforms instead of 2X10 nominal boards construction grade boards found at most lumberyards. In addition to scaffold grade lumber, Southwest Scaffolding sells both steel and aluminum 7′ and 10′ platforms that are rated for both 50 lbs/sq. ft. and 75 lbs/sq ft. Another solution to the deflection requirement is to double your planks across the spans that will be receiving materials or equipment such as cubes of brick or block. Also, consider that when you are using outriggers, the weight of your workers on the outrigger platforms will not be applied to the main platform.

See our post on load limits on scaffolding frames here.