Use with Portable Ladders, Chapter 296-876 WAC

This Helpful Tool provides information concerning the design and construction of job-made wooden ladders. Ladders that are built according to these specifications will be considered to meet the requirements of Design and Construction, WAC 296-876-20005.

GENERAL REQUIREMENTS

• All ladder component surfaces are finished to avoid injury to employees and to prevent snagging of clothing.
• Working length isn't greater than 24 feet.
• Fasteners are driven full length and countersunk not more than 1/8 inch.

MATERIALS

• Wood parts are seasoned to moisture content of not more than 19 percent.
• Side rails and cleats are made from stress-grade lumber that meets the minimum grades shown in Table HT-1, Accessible stress-grade lumber for job-made ladders.
• Cleats are nominal 2x4 stress-grade dimension lumber.
• Material used for side rails meets the minimum dimensions of:
  • - Table HT-2, Minimum Rail Size for Single-Cleat Ladders
    or
  • - HT-3, Minimum Rail Size for Double-Cleat Ladders

SIDE RAILS

• The minimum clear distance between rails is:
  • - Uniform throughout the length of climb
    and
  • - At least:
    • 16 inches but not greater than 20 inches for single-cleat ladders
    • 18 inches but not greater than 22 inches for double-cleat ladders

• If splicing is required to obtain the necessary ladder length, the resulting side rail:
  
  • - Doesn't have more than one splice, located as close to the top
    point of bearing as possible
    
  • and
    
  • - Is equivalent in strength to a one-piece side rail made of the same material

• Side rails, if required, are spliced using bolts with a nut and lock washer below the nut. Bolts are either:

• - Common steel bolts with a one inch diameter, 3/32 inch thick steel washer under the bolt head
  or
• - ½ inch diameter carriage bolts

CLEATS

• Cleats are:
  • - Parallel and level when the ladder is in position to be used
    and
  • - Evenly spaced throughout the length of the ladder from the base
    to the top point of bearing.

• The distance from the top of a cleat to the top of an adjacent cleat is at least 8 inches but not greater than 12 inches.

• Cleats on double-cleat ladders are continuous and extend the full width of the ladder.

ATTACHING CLEATS

• Cleats are attached to the narrow face of each side rail by three 3 ¼ inch long 12-d common nails, or an equivalent set of fasteners.

• Filler blocks are used between cleats. Side rails aren't cut to inset cleats.

• Filler blocks are:
  • - The same thickness as the cleats
  • - Butted tightly against the underside of each cleat
  • - Attached to the side rails by three 3 ¼ inch long 12-d common nails, or an equivalent set of fasteners.

  Table HT-1 Acceptable Stress-Grade Lumber for Job-Made Ladders
  Species for Visual Grades and Machine Grading Acronyms	Minimum Grade
  Aspen	Select Structural
  Beech-Birch-Hickory	No. 2
  Cottonwood	Select Structural
  Douglas Fir-Larch	No. 2
  Douglas Fir-Larch (north)	No. 1/No. 2
  Douglas-Fir-Larch (south)	No. 2
  Eastern Hemlock-Tamarack	Select Structural
  Eastern Softwoods	Select Structural
  Eastern White Pine	Select Structural
  Hem-Fir	No. 2
  Hem-Fir (north)	No. 1/No. 2
  Mixed Maple	Select Structural
  Mixed Oak	No. 2
  Northern Red Oak	No. 2
  Northern Species	Select Structural
  Red Maple	No. 2
  Red Oak	No. 2
  Redwood	No. 1
  Spruce-Pine-Fir	No. 1/No. 2
  Spruce-Pine-Fir (south)	No. 1
  Southern Pine	No. 2 (nondense)
  Western Cedars	Select Structural
  Western Woods	Select Structural
  White Oak	No. 2
  Yellow Popular	Select Structural
  MSR	1200f-1.2E
  MEL	M-7
  Note: The allowable stress in bending after adjustment for size, Fb, shall not be less than 1200 psi (pound-force per square inch) and the corresponding reference strength (for Load and Resistance Factor Design) shall not be less than 3.05 ksi (kips-force per square inch)