- Part Number:1926
- Part Number Title:Safety and Health Regulations for Construction
- Subpart:1926 Subpart L
- Subpart Title:Scaffolds
- Standard Number:
- Title:Scaffold Specifications
- GPO Source:
(Non-mandatory) Appendix A to Subpart L of Part 1926—Scaffold Specifications
This appendix provides non-mandatory guidelines to assist employers in complying with the requirements of subpart L of this part. An employer may use these guidelines and tables as a starting point for designing scaffold systems. However, the guidelines do not provide all the information necessary to build a complete system, and the employer is still responsible for designing and assembling these components in such a way that the completed system will meet the requirements of § 1926.451(a). Scaffold components which are not selected and loaded in accordance with this Appendix, and components for which no specific guidelines or tables are given in this appendix (e.g., joints, ties, components for wood pole scaffolds more than 60 feet in height, components for heavy-duty horse scaffolds, components made with other materials, and components with other dimensions, etc.) must be designed and constructed in accordance with the capacity requirements of § 1926.451(a), and loaded in accordance with § 1926.451(d)(1).
Index to appendix A for Subpart L
- General guidelines and tables.
- Specific guidelines and tables.
- Pole scaffolds:
Single-pole wood pole scaffolds.
Independent wood pole scaffolds. - Tube and coupler scaffolds.
- Fabricated frame scaffolds.
- Plasterers', decorators' and large area scaffolds.
- Bricklayers' square scaffolds.
- Horse scaffolds.
- Form scaffolds and carpenters' bracket scaffolds.
- Roof bracket scaffolds.
- Outrigger scaffolds (one level).
- Pump jack scaffolds.
- Ladder jack scaffolds.
- Window jack scaffolds.
- Crawling boards (chicken ladders).
- Step, platform and trestle ladder scaffolds.
- Single-point adjustable suspension scaffolds.
- Two-point adjustable suspension scaffolds.
-
- Stonesetters' multi-point adjustable suspension scaffolds.
- Masons' multi-point adjustable suspension scaffolds.
- Catenary scaffolds.
- Float (ship) scaffolds.
- Interior hung scaffolds.
- Needle beam scaffolds.
- Multi-level suspension scaffolds.
- Mobile scaffolds.
- Repair bracket scaffolds.
- Stilts.
- Tank builders' scaffolds.
- Pole scaffolds:
General Guidelines and Tables
The following tables, and the tables in part 2—Specific guidelines and tables, assume that all load-carrying timber members (except planks) of the scaffold are a minimum of 1,500 lb-f/in2 (stress grade) construction grade lumber. All dimensions are nominal sizes as provided in the American Softwood Lumber Standards, dated January 1970, except that, where rough sizes are noted, only rough or undressed lumber of the size specified will satisfy minimum requirements.
Solid sawn wood used as scaffold planks shall be selected for such use following the grading rules established by a recognized lumber grading association or by an independent lumber grading inspection agency. Such planks shall be identified by the grade stamp of such association or agency. The association or agency and the grading rules under which the wood is graded shall be certified by the Board of Review, American Lumber Standard Committee, as set forth in the American Softwood Lumber Standard of the U.S. Department of Commerce.
Allowable spans shall be determined in compliance with the National Design Specification for Wood Construction published by the National Forest Products Association; paragraph 5 of ANSI A10.8–1988 Scaffolding-Safety Requirements published by the American National Standards Institute; or for 2 × 10 inch (nominal) or 2 × 9 inch (rough) solid sawn wood planks, as shown in the following table:
| Maximum intended nominal load (lb/ft2) |
Maximum permissible span using full thickness undressed lumber (ft) |
Maximum permissible span using nominal thickness lumber (ft) |
|---|---|---|
| 25 | 10 | 8 |
| 50 | 8 | 6 |
| 75 | 6 | - |
The maximum permissible span for 1¼ × 9-inch or wider wood plank of full thickness with a maximum intended load of 50 lb/ft.2 shall be 4 feet.
Fabricated planks and platforms may be used in lieu of solid sawn wood planks. Maximum spans for such units shall be as recommended by the manufacturer based on the maximum intended load being calculated as follows:
| Rated load capacity |
Intended load |
|---|---|
| Light-duty | • 25 pounds per square foot applied uniformly over the entire span area. |
| Medium-duty | • 50 pounds per square foot applied uniformly over the entire span area. |
| Heavy-duty | • 75 pounds per square foot applied uniformly over the entire span area. |
| One-person | • 250 pounds placed at the center of the span (total 250 pounds). |
| Two-person | • 250 pounds placed 18 inches to the left and right of the center of the span (total 500 pounds). |
| Three-person | • 250 pounds placed at the center of the span and 250 pounds placed 18 inches to the left and right of the center of the span (total 750 pounds). |
Note: Platform units used to make scaffold platforms intended for light-duty use shall be capable of supporting at least 25 pounds per square foot applied uniformly over the entire unit-span area, or a 250-pound point load placed on the unit at the center of the span, whichever load produces the greater shear force.
Guardrails shall be as follows:
Toprails shall be equivalent in strength to 2 inch by 4 inch lumber; or
- 1 ¼ inch × ⅛ inch structural angle iron; or
- 1 inch × .070 inch wall steel tubing; or 1.990 inch × .058 inch wall aluminum tubing.
Midrails shall be equivalent in strength to 1 inch by 6 inch lumber; or
- 1 ¼ inch × 1¼ inch × ⅛ inch structural angle iron; or
- 1 inch × .070 inch wall steel tubing; or
1.990 inch × .058 inch wall aluminum tubing.
Toeboards shall be equivalent in strength to 1 inch by 4 inch lumber; or
- 1 ¼ inch × 1¼ inch structural angle iron; or
- 1 inch × .070 inch wall steel tubing; or
1.990 inch × .058 inch wall aluminum tubing.
Posts shall be equivalent in strength to 2 inch by 4 inch lumber; or
- 1¼ inch x 1 ¼ inch x ⅛ structural angle iron; or
- 1inch x .070 inch wall steel tubing; or
1.990 inch x .058 inch wall aluminum tubing.
Overhead protection shall consist of 2 inch nominal planking laid tight, or ¾-inch plywood.
Specific guidelines and tables.
Pole Scaffolds.
| - | Light duty up to 20 feet high | Light duty up to 60 feet high | Medium duty up to 60 feet high | Heavy duty up to 60 feet high |
|---|---|---|---|---|
| Maximum intended load (lbs/ft2) | 25 | 25 | 50 | 75 |
| Poles or uprights | 2 × 4 in | 4 × 4 in | 4 × 4 in | 4 × 6 in. |
| Maximum pole spacing (longitudinal) | 6 feet | 10 feet | 8 feet | 6 feet |
| Maximum pole spacing (transverse) | 5 feet | 5 feet | 5 feet | 5 feet |
| Runners | 1 × 4 in | 1¼ × 9 in | 2 × 10 in | 2 × 10 in. |
| Bearers and maximum spacing of bearers: | - | - | - | - |
| 3 feet | 2 × 4 in | 2 × 4 in | 2 × 10 in. or 3 × 4 in | 2 × 10 in. or 3 × 5 in. |
| 5 feet | 2 × 6 in. or 3 × 4 in | 2 × 6 in. or 3 × 4 in. (rough) | 2 × 10 in. or 3 × 4 in | 2 × 10 in. or 3 × 5 in. |
| 6 feet | - | - | 2 × 10 in. or 3 × 4 in | 2 × 10 in. or 3 × 5 in. |
| 8 feet | - | - | 2 × 10 in. or 3 × 4 in | - |
| Planking | 1¼ × 9 in | 2 × 10 in | 2 × 10 in | 2 × 10 in. |
| Maximum vertical spacing of horizontal members | 7 feet | 9 feet | 7 feet | 6 ft. 6 in. |
| Bracing horizontal | 1 × 4 in | 1 × 4 in | 1 × 6 in. or 1¼ × 4 in | 2 × 4 in. |
| Bracing diagonal | 1 × 4 in | 1 × 4 in | 1 × 4 in | 2 × 4 in. |
| Tie-ins | 1 × 4 in | 1 × 4 in | 1 × 4 in | 1 × 4 in. |
NOTE: All members except planking are used on edge. All wood bearers shall be reinforced with 3⁄16 x 2 inch steel strip, or the equivalent, secured to the lower edges for the entire length of the bearer.
| - | Light duty up to 20 feet high | Light duty up to 60 feet high | Medium duty up to 60 feet high | Heavy duty up to 60 feet high |
|---|---|---|---|---|
| Maximum intended load | 25 lbs/ft2 | 25 lbs/ft2 | 50 lbs/ft2 | 75 lbs/ft2. |
| Poles or uprights | 2 × 4 in | 4 × 4 in | 4 × 4 in | 4 × 4 in. |
| Maximum pole spacing (longitudinal) | 6 feet | 10 feet | 8 feet | 6 feet. |
| Maximum (transverse) | 6 feet | 10 feet | 8 feet | 8 feet. |
| Runners | 1¼ × 4 in | 1¼ × 9 in | 2 × 10 in | 2 × 10 in. |
| Bearers and maximum spacing of bearers: | ||||
| 3 feet | 2 × 4 in | 2 × 4 in | 2 × 10 in | 2 × 10 in. (rough). |
| 6 feet | 2 × 6 in. or 3 × 4 in | 2 × 10 in. (rough) or 3 × 8 in | 2 × 10 in | 2 × 10 in. (rough). |
| 8 feet | 2 × 6 in. or 3 × 4 in | 2 × 10 in. (rough) or 3 × 8 in | 2 × 10 in | |
| 10 feet | 2 × 6 in. or 3 × 4 in | 2 × 10 in. (rough) or 3 × 3 in | ||
| Planking | 1¼ × 9 in | 2 × 10 in | 2 × 10 in | 2 × 10 in. |
| Maximum vertical spacing of horizontal members | 7 feet | 7 feet | 6 feet | 6 feet. |
| Bracing horizontal | 1 × 4 in | 1 × 4 in | 1 × 6 in. or 1¼ × 4 in | 2 × 4 in. |
| Bracing diagonal | 1 × 4 in | 1 × 4 in | 1 × 4 in | 2 × 4 in. |
| Tie-ins | 1 × 4 in | 1 × 4 in | 1 × 4 in | 1 × 4 in. |
NOTE: All members except planking are used on edge. All wood bearers shall be reinforced with 3⁄16 x 2 inch steel strip, or the equivalent, secured to the lower edges for the entire length of the bearer.
Tube and coupler scaffolds.
| - | Light duty | Medium duty | Heavy duty |
|---|---|---|---|
| Maximum intended load | 25 lbs/ft2 | 50 lbs/ft2 | 75 lbs/ft2. |
| Posts, runners and braces | Nominal 2 in. (1.90 inches) OD steel tube or pipe | Nominal 2 in. (1.90 inches) OD steel tube or pipe | Nominal 2 in. (1.90 inches) OD steel tube or pipe. |
| Bearers | Nominal 2 in. (1.90 inches) | Nominal 2 in. (1.90 inches) | Nominal 2½ in. (2.375 in.). |
| - | OD steel tube or pipe and a maximum post spacing of 4 ft. × 10 ft. | OD steel tube or pipe and a maximum post spacing of 4 ft. × 7 ft. or | OD steel tube or pipe and a maximum post spacing of 6 ft. × 6 ft. |
| - | - | Nominal 2½ in. (2.375 in.) | - |
| - | - | OD steel tube or pipe and a maximum post spacing of 6 ft. × 8 ft. * | - |
| Maximum runner spacing vertically | 6 ft. 6 in | 6 ft. 6 in | 6 ft. 6 in. |
* Bearers shall be installed in the direction of the shorter dimension.
NOTE: Longitudinal diagonal bracing shall be installed at an angle of 45° (±5°).
| - | Maximum number of additional planked levels | Maximum height of scaffold (in feet) |
||
|---|---|---|---|---|
| Light duty | Medium duty | Heavy duty | ||
| Number of Working Levels: | ||||
| 1 | 16 | 11 | 6 | 125 |
| 2 | 11 | 1 | 0 | 125 |
| 3 | 6 | 0 | 0 | 125 |
| 4 | 1 | 0 | 0 | 125 |
Bricklayers' square scaffolds.
Maximum intended load: 50 lb/ft.[2] *
Maximum width: 5 ft.
Maximum height: 5 ft.
Gussets: 1 × 6 in.
Braces: 1 × 8 in.
Legs: 2 × 6 in.
Bearers (horizontal members): 2 × 6 in
Horse scaffolds.
Maximum intended load (light duty): 25 lb/ft.[2] **
Maximum intended load (medium duty): 50 lb/ft.2 **
Horizontal members or bearers:
Light duty: 2 × 4 in.
Medium duty: 3 × 4 in.
Legs: 2 × 4 in.
Longitudinal brace between legs: 1 × 6 in.
Gusset brace at top of legs: 1 × 8 in.
Half diagonal braces: 2 × 4 in
Brackets shall consist of a triangular-shaped frame made of wood with a cross-section not less than 2 inches by 3 inches, or of 1¼ inch × 1¼ inch × ⅛ inch structural angle iron.
Bolts used to attach brackets to structures shall not be less than 5⁄8 inches in diameter.
Wooden figure-four scaffolds:
Maximum intended load: 25 lb/ft.2
Uprights: 2 × 4 in. or 2 × 6 in.
Bearers (two): 1 × 6 in.
Braces: 1 × 6 in.
Maximum length of bearers (unsupported): 3 ft. 6 in
Metal bracket scaffolds:
Maximum intended load: 25 lb/ft.2
Uprights: 2 × 4 inch
Bearers: As designed.
Braces: As designed.
Wood bracket scaffolds:
Maximum intended load: 25 lb/ft.2
Uprights: 2 × 4 in or 2 × 6 in
Bearers: 2 × 6 in
Maximum scaffold width: 3 ft 6 in
Braces: 1 × 6 in
Ladder jack scaffolds. Maximum intended load—25 lb/ft2. However, not more than two employees shall occupy any platform at any one time. Maximum span between supports shall be 8 feet.
Single-point adjustable suspension scaffolds. Maximum intended load—250 lbs. Wood seats for boatswains' chairs shall be not less than 1 inch thick if made of non-laminated wood, or 5⁄8 inches thick if made of marine quality plywood.
In addition to direct connections to buildings (except window cleaners' anchors) acceptable ways to prevent scaffold sway include angulated roping and static lines. Angulated roping is a system of platform suspension in which the upper wire rope sheaves or suspension points are closer to the plane of the building face than the corresponding attachment points on the platform, thus causing the platform to press against the face of the building. Static lines are separate ropes secured at their top and bottom ends closer to the plane of the building face than the outermost edge of the platform. By drawing the static line taut, the platform is drawn against the face of the building.
On suspension scaffolds designed for a working load of 500 pounds, no more than two employees shall be permitted on the scaffold at one time. On suspension scaffolds with a working load of 750 pounds, no more than three employees shall be permitted on the scaffold at one time.
Ladder-type platforms. The side stringer shall be of clear straight-grained spruce. The rungs shall be of straight-grained oak, ash, or hickory, at least 1⅛ inches in diameter, with ⅞ inch tenons mortised into the side stringers at least ⅞ inch. The stringers shall be tied together with tie rods not less than ¼ inch in diameter, passing through the stringers and riveted up tight against washers on both ends. The flooring strips shall be spaced not more than ⅝ inch apart, except at the side rails where the space may be 1 inch. Ladder-type platforms shall be constructed in accordance with the following table:
| Length of Platform | 12 feet | 14 & 16 feet | 18 & 20 feet. |
| Side stringers, minimum cross section (finished sizes): | - | - | - |
| At ends | 1¾ × 2¾ in | 1¾ × 2¾ in | 1¾ × 3 in. |
| At middle | 1¾ × 3¾ in | 1¾ × 3¾ in | 1¾ × 4 in. |
| Reinforcing strip (minimum) | A ⅛ × ⅞ inch steel reinforcing strip shall be attached to the side or underside, full length. | ||
| Rungs | Rungs shall be 1⅛ inch minimum diameter with at least ⅞ inch in diameter tenons, and the maximum spacing shall be 12 inches to center. | ||
| Tie rods: | - | - | - |
| Number (minimum) | 3 | 4 | 4 |
| Diameter (minimum) | ¼ inch | ¼ inch | ¼ inch |
| Flooring, minimum finished size | ½ × 2¾ in | ½ × 2¾ in | ½ × 2¾ in. |
| Length of Platform | 22 & 24 ft | 28 & 30 ft. |
| Side stringers, minimum cross section (finished sizes): | - | - |
| At ends | 1¾ × 3 in | 1¾ × 3½ in. |
| At middle | 1¾ × 4¼ in | 1¾ × 5 in. |
| Reinforcing strip (minimum) | A ⅛ × ⅞-inch steel reinforcing strip shall be attached to the side or underside, full length. | |
| Rungs | Rungs shall be 1⅛ inch minimum diameter with at least ⅞ inch in diameter tenons, and the maximum spacing shall be 12 inches to center. Tie rods. | |
| Number (minimum) | 5 | 6. |
| Diameter (minimum) | ¼ in | ¼ in. |
| Flooring, minimum finished size | ½ × 2¾ in | ½ × 2¾ in. |
Interior hung scaffolds.
Bearers (use on edge): 2 × 10 in.
Maximum intended load: Maximum span
25 lb/ft.2: 10 ft.
50 lb/ft.2: 10 ft.
75 lb/ft.2: 7 ft.
Needle beam scaffolds.
Maximum intended load: 25 lb/ft.2
Beams: 4 × 6 in.
Maximum platform span: 8 ft.
Maximum beam span: 10 ft.
* The squares shall be set not more than 8 feet apart for light duty scaffolds and not more than 5 feet apart for medium duty scaffolds.
** Horses shall be spaced not more than 8 feet apart for light duty loads, and not more than 5 feet apart for medium duty loads.
[61 FR 46025, Aug. 30, 1996; 77 FR 46950, Aug. 7, 2012]