Q: My job superintendent just rented some scaffolding. The company we rented the scaffolding from wanted to know what type of scaffold planks we needed. My man indicated we were using them on masonry construction and this answer seemed to satisfy the rental company. Why does the rental company want to know what we are doing with the planks?

A: Occupational Safety and Health Administration (OSHA) has requirements for wood scaffold planks. It requires all planks to be at least a nominal 2x10, Scaffold Grade. The allowable plank span to be determined by the type of loading. Three types of loading are recognized:

  • Light-duty loading: Supports a working load not to exceed 25 pounds per square foot (psf). Suitable for the support of workers and tools, no material storage.
  • Medium-duty loading: Supports a working load not to exceed 50 psf. Often described as applying to bricklayers' or plasterers' work.
  • Heavy-duty loading: Supports a working load not to exceed 75 psf. Sometimes applied to stone masonry work.

The table below, taken from the current OSHA standards, indicates the allowable spans for 2xl0-inch or wider planks.Loads on masonry planks and scaffolds can be quite high. Your rental company was probably trying to determine if the scaffold plank, the scaffolding, and your use were all compatible.

Full Thickness Undressed Lumber Nominal Thickness
Light Med. Heavy Light Med. Heavy
Load, psf
25 50 75 25 50 75
Span, ft
10 8 6 8 6 *
*Nominal thickness lumber not recommended for heavy-duty use.

Editor's note:OSHA regulations may have changed since this article was first published. Please make sure you are following the current OSHA regulations.