Labor & Industries (L&I), Washington State

Portable Ladders Chapter 296-876, WAC

Effective Date: 01/01/06

WAC 296-876 Helpful Tool: Job-Made Wooden Ladders Design and Construction

For printing

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.

Note: Fasteners include plain-shank and helically-threaded steel nails. Staples and wood screws of equivalent shank withdrawal, head pull-through, and bending/shear resistance (as determined by test data or published formulas and tabulated values) may also be used.

Definition: Equivalent means an alternative design, material or method to protect against a hazard. You have to demonstrate it provides an equal or greater degree of safety for employees than the method, material or design specified in the rule.

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

Note: Minimum dimensions for side rails are based on the ladder being set-up at the proper angle. See Set-up , WAC 296-876-40020.

Definition: Double-cleat ladder is a job-made ladder with two side rails and a center rail connected with continuous cleats. It allows personnel to climb and descend at the same time. Single-cleat ladder is a ladder consisting of a pair of side rails connected by cleats, rungs, or steps. Stress-grade lumber is lumber that has been assigned allowable stress (allowable stress design) or reference strengths (load resistance factor design) values. It is identified by the grademark or certificate of inspection issued by a lumber inspection bureau or agency accredited by the Board of Review of the American Lumber Standard Committee. The grademark specifies the grade, species, and dryness of the lumber.

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)

 

Table HT-2 Minimum Rail Size for Single-Cleat Ladders (Nominal-Dimension Lumber)
Working Length (feet)	Spliced Side Rail	Continuous Side Rail
12 or less	2x4	2x4
14	2x4	2x4
16	2x4	2x6
18	2x4	2x6
20	2x6	2x6
22	2x6	2x6
24	2x6	2x6

 

Table HT-3 Minimum Rail Size for Double-Cleat Ladders (Nominal-Dimension Lumber)
Working Length (feet)	Spliced Side Rail	Continuous Side Rail
12 or less	2x4	2x4
14	2x4	2x6
16	2x6	2x6
18	2x6	2x6
20	2x6	Stresses exceed capacity of 2x6 rails
22	2x6
24	2x6