Portable Ladders

Chapter 296-876, WAC

Effective Date: 01/01/06

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WAC 296-876

Helpful Tool: Job-Made Wooden Ladders Design and Construction

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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

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

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

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

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

 

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