Non-mandatory scaffold guidelines

The guidelines in Appendix A are non-mandatory and optional, but the employer must still ensure the finished scaffold meets the mandatory capacity and loading requirements in the Scaffold Standard. Employers may use Appendix A as a starting point, but they remain responsible for designing and assembling scaffold components so the completed system complies with the capacity requirements in 1926.451(a) and for loading the scaffold in accordance with 1926.451(d)(1). See also the Appendix A statement: "This appendix provides non-mandatory guidelines." (1926.SubpartLAppA).

Solid sawn wood scaffold planks must be selected and identified according to the grading rules of a recognized lumber grading association or an independent lumber grading inspection agency, and the planks must bear that association's grade stamp. Appendix A states that "Solid sawn wood used as scaffold planks shall be selected for such use following the grading rules established by a recognized lumber grading association... and shall be identified by the grade stamp" (1926.SubpartLAppA(1)(b)). Employers must still ensure the finished scaffold meets the capacity and loading rules in 1926.451(a) and 1926.451(d)(1).

For 2 × 10 nominal solid sawn wood planks, Appendix A gives the following maximum permissible spans based on intended uniform loads: 10 ft for 25 lb/ft² using full-thickness undressed lumber (8 ft for nominal thickness), 8 ft for 50 lb/ft² (6 ft nominal), and 6 ft for 75 lb/ft² (full thickness only). These spans are shown in the table under 1926.SubpartLAppA(1)(b)(i). Remember these are non-mandatory guidelines and the scaffold must meet the capacity requirements of 1926.451(a).

The maximum permissible span for 1¼ × 9 inch (full thickness) wood plank under a 50 lb/ft² intended uniform load is 4 feet. This specific span limit is stated in 1926.SubpartLAppA(1)(b)(ii). Ensure the completed scaffold still meets the mandatory capacity and loading requirements in 1926.451(a) and 1926.451(d)(1).

Employers should use the manufacturer's recommended maximum spans for fabricated planks and platforms, based on the unit's rated load capacity and the intended load calculation described in Appendix A. Appendix A explains that fabricated planks "may be used in lieu of solid sawn wood planks" and that "Maximum spans for such units shall be as recommended by the manufacturer based on the maximum intended load" (1926.SubpartLAppA(1)(c)). Regardless of manufacturer guidance, the employer remains responsible for meeting 1926.451(a) capacity and 1926.451(d)(1) loading requirements for the completed scaffold.

Appendix A gives equivalent materials and strengths for guardrail components: toprails equivalent to 2×4 lumber or listed metal tubing/angle sizes; midrails equivalent to 1×6 lumber or listed metal tubing/angle sizes; toeboards equivalent to 1×4 lumber or listed metal tubing/angle sizes; and posts equivalent to 2×4 lumber or listed metal tubing/angle sizes, with distance between posts not to exceed 8 feet. See the specific component listings under 1926.SubpartLAppA(1)(d). These are non-mandatory equivalencies—employers must still meet the guardrail and fall-protection requirements found in the applicable scaffold standard (1926.451).

Appendix A recommends overhead protection be constructed of 2-inch nominal planking laid tight or 3/4-inch plywood. This recommendation appears under 1926.SubpartLAppA(1)(e). Employers must also comply with mandatory falling-object protection requirements in the Scaffold Standard (1926.451).

Appendix A recommends that screen installed between toeboards and midrails or toprails be No. 18 gauge U.S. Standard wire with one-inch mesh. This screening specification is in 1926.SubpartLAppA(1)(f). Use of screens does not replace compliance with the mandatory falling-object protection provisions in 1926.451.

Appendix A provides recommended pole/upright sizes, pole spacing, runners, bearers and planking for single-pole wood pole scaffolds by duty level: for light duty up to 20 ft use 2×4 poles and 1¼×9 in planking; for light duty up to 60 ft use 4×4 poles and 2×10 planking; for medium duty up to 60 ft use 4×4 poles and 2×10 planking; and for heavy duty up to 60 ft use 4×6 poles and 2×10 planking. These recommendations and the associated spacings and bracing are shown in 1926.SubpartLAppA(2)(a). Remember these are guidelines; the completed scaffold must satisfy the mandatory capacity and loading requirements in 1926.451(a) and 1926.451(d)(1).

Appendix A recommends nominal 2-inch (1.90 in.) OD steel tube or pipe for posts, runners and braces for light and medium duty tube-and-coupler scaffolds, with bearers increasing to nominal 2½ in. (2.375 in.) OD for heavy duty; maximum post spacings vary by duty (examples: light-duty post spacing up to 4 ft × 10 ft; medium up to 4 ft × 7 ft or 6 ft × 8 ft in some configurations; heavy up to 6 ft × 6 ft). These details are provided in 1926.SubpartLAppA(2)(b). Also see the guidance on maximum number of planked levels and maximum scaffold heights in the same subsection. Employers must still ensure compliance with the mandatory Scaffold Standard (1926.451).

Appendix A states that because fabricated frame scaffolds are prefabricated, no additional guidelines or tables are included and employers should rely on the manufacturer's design and recommendations. See 1926.SubpartLAppA(2)(c). Manufacturers' instructions must be followed and the completed scaffold must meet the mandatory requirements in 1926.451(a).

Appendix A advises that the guidelines for pole scaffolds or tube-and-coupler scaffolds found in the earlier subsections may be applied to plasterers', decorators', and large area scaffolds. This direction is in 1926.SubpartLAppA(2)(d). Employers must still ensure the resulting scaffold complies with the binding Scaffold Standard (1926.451).

Appendix A specifies bricklayers' square scaffolds should have a maximum intended load of 50 lb/ft², maximum width of 5 ft, and maximum height of 5 ft; gussets 1×6 in, braces 1×8 in, legs 2×6 in, and horizontal bearers 2×6 in. See 1926.SubpartLAppA(2)(e). These are non-mandatory guidelines and the completed scaffold must meet mandatory requirements in 1926.451(a).

Appendix A gives two intended-load categories for horse scaffolds: light duty at 25 lb/ft² and medium duty at 50 lb/ft². Recommended horizontal members or bearers are 2×4 in for light duty and 3×4 in for medium duty; legs 2×4 in; longitudinal brace 1×6 in; gusset brace at top 1×8 in; and half diagonal braces 2×4 in. See 1926.SubpartLAppA(2)(f). Employers must still verify the scaffold meets mandatory capacity and loading rules in 1926.451(a) and 1926.451(d)(1).

Appendix A recommends brackets be triangular wooden frames with cross-section not less than 2×3 in or 1¼×1¼×1/8 in structural angle iron; bolts attaching brackets to structure be at least 5/8 in diameter; maximum bracket spacing 8 ft on centers; and no more than two employees shall occupy any given 8 ft of a bracket or form scaffold at one time, with tools/materials limited to 75 lb in addition to occupants. See 1926.SubpartLAppA(2)(g)(1)–(4). These are non-mandatory guidelines—employers must ensure the assembled scaffold meets mandatory capacity requirements in 1926.451(a).

Appendix A states wooden figure‑four brackets' bearers shall project not more than 3 feet 6 inches from the outside of the form support, must be braced and secured to prevent tipping or turning, and the knee or angle brace should intersect the bearer at least 3 feet from the form at roughly a 45° angle with the lower end nailed to a vertical support. See 1926.SubpartLAppA(2)(g)(5)(ii). These are guidelines; employers must still meet mandatory scaffold capacity and loading requirements in 1926.451(a) and 1926.451(d)(1).

Appendix A gives recommended maximum intended loads of 25 lb/ft² for both metal bracket scaffolds and wood bracket scaffolds. It lists uprights and bearers for each type (e.g., wood brackets: uprights 2×4 or 2×6 in, bearers 2×6 in, max width 3 ft 6 in). See 1926.SubpartLAppA(2)(g)(6)–(7). These are guidelines; final design must meet the mandatory requirements of 1926.451(a).

Appendix A limits wood poles for pump jack scaffolds to no more than 30 feet in height, specifies a maximum intended load of 500 lbs between poles applied at the center of the span, and states no more than two employees shall be on a pump jack scaffold at one time between any two supports. See 1926.SubpartLAppA(2)(j). Employers must ensure these scaffold assemblies meet the mandatory capacity and loading rules in 1926.451(a) and 1926.451(d)(1).

When Appendix A provides no specific guideline for a component or configuration, the employer must have the component designed and constructed to meet the mandatory capacity requirements of 1926.451(a) and must load it in accordance with 1926.451(d)(1). Appendix A explicitly states components not given specific guidelines "must be designed and constructed in accordance with the capacity requirements of 1926.451(a), and loaded in accordance with 1926.451(d)(1)." (1926.SubpartLAppA).

Appendix A recommends that distance between guardrail posts shall not exceed 8 feet. This is specified in 1926.SubpartLAppA(1)(d)(v). Employers must ensure the completed guardrail system also complies with mandatory requirements in the Scaffold Standard (1926.451).

Appendix A lists metal equivalents to common timber sizes: for toprails it lists 1¼ in × 1/8 in structural angle iron, 1 in × .070 in wall steel tubing, or 1.990 in × .058 in wall aluminum tubing as equivalents to a 2×4 timber; for midrails it lists 1¼ in × 1¼ in × 1/8 in angle iron, 1 in × .070 in wall steel tubing, or 1.990 in × .058 in wall aluminum tubing as equivalents to 1×6 timber; and for toeboards it lists 1¼ in × 1¼ in structural angle iron, 1 in × .070 in steel tubing, or 1.990 in × .058 in aluminum tubing as equivalents to 1×4 timber. See details in 1926.SubpartLAppA(1)(d)(i)–(iii). These are non-mandatory equivalencies; mandatory guardrail requirements remain in the Scaffold Standard (1926.451).

Appendix A recommends that longitudinal diagonal bracing be installed at an angle of 45° (±5°). This bracing requirement appears in 1926.SubpartLAppA(2)(b). Employers must also meet the mandatory scaffold bracing and stability requirements in 1926.451.

Appendix A states that platform units intended for light-duty use must be capable of supporting at least 25 lb/ft² applied uniformly over the entire unit-span area, or a 250-pound point load placed at the center of the span—whichever produces the greater shear force. This guidance is in 1926.SubpartLAppA(1)(c). Even with these design criteria, employers must ensure the assembled scaffold complies with mandatory capacity and loading requirements in 1926.451(a) and 1926.451(d)(1).

Appendix A recommends bolts used to attach brackets to structures be no less than 5/8 inch in diameter. See 1926.SubpartLAppA(2)(g)(2). Employers should verify that bolt selection and bracket anchorage are sufficient to meet the mandatory scaffold strength and capacity requirements in 1926.451(a).

Yes. Appendix A provides recommended maximum vertical spacing of horizontal members for single-pole wood scaffolds: for light duty up to 20 ft the maximum is 7 ft; for light duty up to 60 ft it's 9 ft; for medium duty up to 60 ft it's 7 ft; and for heavy duty up to 60 ft it's 6 ft 6 in. These values are listed in the tables in 1926.SubpartLAppA(2)(a). As always, employers must ensure the scaffold meets the mandatory capacity rules in 1926.451(a).

Yes. OSHA has interpreted conveyances operating with temporary or incomplete guides, temporary suspension means, or temporary hoists (or combinations of these) as meeting the definition of a suspended scaffold under 29 CFR 1926.450(b), and therefore they fall under the Scaffold Standard. The 2023 Letter of Interpretation explains those conveyance configurations are considered suspended scaffolds and that fall protection must meet the requirements of 1926.451(g) (fall protection for scaffolds) and falling-object protection must meet the requirements of 1926.451(h). See the December 5, 2023 Letter of Interpretation regarding scaffold and fall protection (OSHA interpretation, 2023-12-05).

Appendix A notes that all wood bearers (except planking) shall be reinforced with a 3/16 × 2 inch steel strip, or equivalent, secured to the lower edges for the entire length of the bearer. This reinforcement note appears in the pole-scaffold tables in 1926.SubpartLAppA(2)(a). Even with such reinforcement, employers must ensure compliance with the binding Scaffold Standard requirements in 1926.451(a).

You must splice the two 2 × 4s using 10‑penny common nails spaced no more than 12 inches center‑to‑center and staggered from the opposite outside edges. This is the exact construction requirement in 1926.SubpartLAppA(2)(k).

Ladder‑jack scaffolds are limited to a maximum intended load of 25 lb/ft², no more than two employees may be on a platform at one time, and the maximum span between supports is 8 feet. These limits are specified in 1926.SubpartLAppA(2)(l).

Crawling boards must be at least 10 inches wide and 1 inch thick, with cleats that have a minimum cross section of 1 × 1½ inches; the cleats must be full width and spaced at equal intervals not exceeding 24 inches. See 1926.SubpartLAppA(2)(m).

Single‑point adjustable suspension scaffolds have a maximum intended load of 250 pounds; wood seats for boatswain’s chairs must be at least 1 inch thick for non‑laminated wood or 5/8 inch thick if made of marine‑quality plywood. These specifications are in 1926.SubpartLAppA(2)(o).

On two‑point adjustable suspension scaffolds designed for a 500‑pound working load, no more than two employees are permitted; for scaffolds rated at 750 pounds, no more than three employees are permitted. See 1926.SubpartLAppA(2)(p)(2).

Plank‑type platforms must use nominal 2 × 8 inch unspliced planks, fastened underneath with cleats at intervals not exceeding 4 feet (starting 6 inches from each end); a bar or other device must be fastened at each end to prevent slipping off the hanger, and the span between hangers must not exceed 10 feet. These requirements are set out in 1926.SubpartLAppA(2)(p)(4).

Beam‑type platforms must have side stringers of lumber not less than 2 × 6 inches set on edge; the span between hangers must not exceed 12 feet, flooring is supported on 2 × 6 cross beams laid flat at intervals not exceeding 4 feet, and floorboards must not be spaced more than ½ inch apart. See 1926.SubpartLAppA(2)(p)(5).

Ladder‑type platforms must have side stringers of clear straight‑grained spruce; rungs of straight‑grained oak, ash, or hickory at least 1⅛ inches in diameter with ⅞‑inch tenons mortised into the stringers; and tie rods at least ¼ inch in diameter passing through the stringers and riveted against washers at both ends. These construction details appear in 1926.SubpartLAppA(2)(p)(3).

Rungs must be at least 1⅛ inches in diameter with tenons at least ⅞ inch and spaced no more than 12 inches center‑to‑center; flooring minimum finished size is ½ × 2¾ inches; reinforcing steel strip minimum is 1/8 × 7/8 inch; and the minimum number of tie rods increases with platform length (for example, 3 tie rods for 12‑foot platforms, 4 for 14–20 ft, rising up to 6 for 28–30 ft). See the ladder‑type platform schedule in 1926.SubpartLAppA(2)(p)(3).

Catenary scaffolds have a maximum intended load of 500 pounds, permit no more than two employees at a time, require come‑along devices with a maximum capacity of 2,000 pounds, vertical pickups spaced no more than 50 feet apart, and use ropes equivalent in strength to at least ½ inch diameter improved plow steel wire rope. These provisions are in 1926.SubpartLAppA(2)(r).

Float (ship) scaffolds have a maximum intended load of 750 pounds; platforms must be made of ¾‑inch plywood rated equivalent to APA Grade B‑B, Group I, Exterior; bearers must be 2 × 4 inch or 1 × 10 inch rough lumber free of knots and flaws; and ropes must be equivalent to at least 1‑inch first‑grade manila rope. See 1926.SubpartLAppA(2)(s).

Interior hung scaffolds should use 2 × 10 inch bearers set on edge; recommended maximum platform spans are 10 feet for 25 lb/ft² or 50 lb/ft² loads and 7 feet for 75 lb/ft² loads. These guidance values are provided in 1926.SubpartLAppA(2)(t).

Needle beam scaffolds require beams of 4 × 6 inches, a maximum platform span of 8 feet and a maximum beam span of 10 feet; ropes must be attached to needle beams by a scaffold hitch or eye splice with the loose end secured by a bowline or a round turn and a half hitch, and the ropes must be equivalent in strength to at least 1‑inch first‑grade manila rope. See 1926.SubpartLAppA(2)(u) and the attachment and rope strength details in 1926.SubpartLAppA(2)(u)(1) and 1926.SubpartLAppA(2)(u)(2).

An employer may use the stability test methods described in the ANSI A92 series, as appropriate for the scaffold type, to establish stability for purposes of [1926.452(w)(6)], per the non‑mandatory guidance in 1926.SubpartLAppA(2)(w). For the regulatory requirement itself see 1926.452 and the specific paragraph 1926.452(w).

Angulated roping and static lines are methods to keep a suspension scaffold pressed against the building face so it doesn’t swing: angulated roping sets suspension points higher and closer to the building face so the platform bears into the wall, while static lines are separate taut ropes secured above and below the platform and pulled tight to draw the platform against the building. These sway‑prevention methods are described in 1926.SubpartLAppA(2)(p)(1).

Tank‑builder’s scaffold brackets must be spaced no more than 10 feet 6 inches apart; no more than three employees may occupy a 10 feet 6 inch plank span at one time; when the gap between platform and tank shell exceeds 12 inches a taut wire or synthetic rope at plank level may serve as an inner safety line (and a second rope or guardrails must be added if the open space on either side of the rope exceeds 12 inches); planks must be rough full‑dimensioned 2 × 12 inch Douglas Fir or Southern Yellow Pine of Select Structural Grade meeting specified fiber stress and modulus values; guardrails made of taut wire or synthetic rope supported by angle irons must comply with [1926.451(g)(4)]. These tank‑scaffold requirements and plank specifications are in 1926.SubpartLAppA(2)(z) and the guardrail reference is 1926.451(g)(4).

Suspended scaffolds and conveyance‑type suspended platforms meet the Scaffold Standard definition of suspended scaffold and must comply with the fall‑protection requirements in [1926.451(g)]; overhead and falling object protection must meet [1926.451(h)]. OSHA clarified this application to conveyance cars and temporary suspended platforms in its letter of interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2023-12-05, which explains that those conveyances are treated as suspended scaffolds for purposes of fall and falling‑object protection. See 1926.451(g) and the OSHA interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2023-12-05.