The following is a summary of the requirements for scaffolds in construction 29 CFR 1926. 451-454, Subpart L:

1926.451 General Requirements

(a) Capacity.

• Scaffolds and scaffold components shall be capable of supporting, without failure, its own weight and at least 4 times the maximum intended load.
• Each suspension rope, including hardware used on non-adjustable suspension scaffolds, shall be capable of supporting without failure at least 6 times the maximum intended load.
• The stall load of any scaffold hoist shall not exceed 3 times its rated load.
• Scaffolds shall be designed by a qualified person and shall be constructed and loaded in accordance with that design.

(b) Scaffold platform construction.

• Each platform on all working levels of scaffolds shall be fully planked or decked between the front uprights and the guardrail supports.
• Each platform unit shall be installed so that the space between adjacent units and the space between the platform and the uprights is no more than I inch wide, except where the employer can demonstrate that a wider space is necessary.
• Each scaffold walkway shall be at least 18 inches wide.
• The front edge of all platforms shall not be more than 14 inches from the face of the work, unless guardrail systems are erected along the front edge and/or personal fall arrest systems are used.
• Each end of a platform, unless cleated or otherwise restrained by hooks or equivalent means, shall extend over the centerline of its support at least 6 inches.
• Each end of a platform 10 feet or less in length shall not extend over its supports more than 12 inches unless otherwise designated.
• Each platform greater than 10 feet shall not extend over its support more than 1 8 inches unless otherwise designated
• On scaffolds where platforms are abutted to create a long platform, each abutted end shall rest on a separate support surface.
• On scaffolds where platforms are overlapping to create a long platform, the overlap shall occur only over supports, and shall not be less than 12 inches unless the platforms are nailed together or otherwise restrained to prevent movement.
• At all points of a scaffold where the platform changes direction, any platform that rests on a bearer at an angle other than a right angle shall be laid first, and platforms which rest at right angles over the same bearer shall be laid second.
• Wood platforms shall not be covered with opaque finishes unless otherwise designated.
• Scaffold components manufactured by different manufacturers shall not be intermixed unless the components fit together without force and the scaffold's structural integrity is maintained by the user. Scaffold components manufactured by different manufacturers shall not be modified in order to intermix them unless a competent person determines the resulting scaffold is structurally sound.
• Scaffold components made of dissimilar metals shall not be used together unless a competent person has determined that the galvanic action will not reduce the strength of any component to a level below that which is required by the standard.

(c) Criteria for supported scaffolds.

• Supported scaffolds with a height to base width ratio of more than four to one (4: 1) shall be restrained from tipping by guying, tying, bracing, or equivalent means.
• Guys, ties, and braces shall be installed according to the scaffold manufacturer's recommendations or at the closest horizontal member to the 4:1 height and be repeated vertically at locations of horizontal members every 20 feet or less thereafter for scaffolds 3 feet wide or less, and every 26 feet or less thereafter for scaffolds greater than 3 feet wide.
• The top guy, tie or brace of completed scaffolds shall be placed no further than 4:1 height from the top. Such guys, ties and braces shall be installed at each end of the scaffold and at horizontal intervals not to exceed 30 feet.
• Supported scaffold poles, legs, posts, frames, and uprights shall bear on base plates, mud sills or other adequate firm foundations.
• Supported scaffold poles, legs, posts, frames, and uprights shall be plumb and braced to prevent swaying and displacement.

(d) Criteria for suspension scaffolds.

• All suspension scaffold support devices, such as outrigger beams, cornice hooks, parapet clamps, and similar devices, shall rest on surfaces capable of supporting at least 4 times the load imposed on them by the scaffold operating at the rated load of the hoist.
• Suspension scaffold outrigger beams, when used, shall be made of structural metal or equivalent strength material, and shall be restrained to prevent movement.
• Inboard ends of suspension scaffold outrigger beams shall be stabilized by bolts or other direct connections to the floor or roof deck, or they shall have their inboard ends stabilized by counterweights, except for masons' multi-point adjustable suspension scaffold outrigger beams which shall not be stabilized by counterweights.
• Suspension scaffold outrigger beams shall be:

1. Provided with stop bolts or shackles at both ends.
2. Securely fastened together with the flanges turned out when channel iron beams are used in place of I-beams.
3. Installed with all bearing supports perpendicular to the center line.
4. Set and maintained with the web in a vertical position.
5. When an outrigger beam is used, the shackle or clevis with which the rope is attached to the outrigger beam shall be placed directly over the center line of the stirrup.

• Suspension scaffolds support devices such as cornice hooks, roof hooks, roof irons, parapet clamps, or similar devices shall be:

1. Made of steel, wrought iron, or material of equivalent strength.
2. Supported by bearing blocks.
3. Secured against movement by tiebacks installed at right angles to the face of the building or structure, or opposing angle tiebacks shall be installed and secured to a structurally sound point of anchorage on the building or structure.
4. Tiebacks shall be equivalent in strength to the hoisting rope.

• When winding drum hoists are used on a suspension scaffold, they shall contain not less than four wraps of the suspension rope at the lowest point of scaffold travel.
• The use of repaired wire rope as suspension rope is prohibited.
• Wire suspension ropes shall not be joined together except through the use of eye splice thimbles connected with shackles or coverplates and bolts.
• The load end of wire suspension ropes shall be equipped with proper size thimbles and secured by eyesplicing or equivalent means.
• Ropes shall be inspected for defects by a competent person prior to each workshift and after every occurrence which could affect a rope's integrity.
• Swaged attachments or spliced eyes on wire suspension ropes shall not be used unless they are made by the wire rope manufacturer or qualified person.
• When wire rope clips are used on suspension scaffold:

1. There shall be a minimum of 3 wire rope clips installed, with the clips a minimum of 6 rope diameters apart.
2. Clips shall be installed according to the manufacturer's recommendations.
3. Clips shall be retightened to the manufacturer's recommendations after the initial loading.
4. Clips shall be inspected and retightened to the manufacturer's recommendations at the start of each workshift thereafter.
5. When U-bolts clips are used, the U-bolt shall be placed over the dead end of the rope, and the saddle shall be placed over the live end of the rope.

• Suspension scaffold power-operated hoists and manual hoists shall be tested and listed by a qualified testing laboratory.
• Gasoline-powered equipment and hoists shall not be used on suspension scaffolds.
• Gears and brakes of power-operated hoists used on suspension scaffolds shall be enclosed.
• In addition to the normal operating brake, suspension scaffold power-operated hoists and manually operated hoists shall have a braking device or locking pawl which engages automatically when a hoist makes either of the following uncontrolled movements: an instantaneous change in momentum or an accelerated overspeed.
• Manually operated hoists shall require a positive crank force to descend.
• Two-point and multi-point suspension scaffolds shall be tied or otherwise secured to prevent them from swaying, as determined to be necessary based on an evaluation by a competent person.
• Devices whose sole function is to provide emergency escape and rescue shall not be used as working platforms.

(e) Access.

• When scaffold platforms are more than 2 feet above or below a point of access, portable ladders, hook-on ladders, attachable ladders, stairtowers, ramps, walkways, integral prefabricated scaffold access, or direct access from another scaffold, structure, personnel hoist, or similar surface shall be used.
• Portable, hook-on, and attachable ladders shall be positioned so as not to tip the scaffold.
• Hook-on and attachable ladders shall be positioned so that their bottom rung is not more than 24 inches above the scaffold supporting level.
• When hook-on and attachable ladders are used on a supported scaffold more than 35 feet high, they shall have rest platforms at 35-foot maximum vertical intervals.
• Hook-on and attachable ladders shall be specifically designed for use with the type of scaffold used.
• Hook-on and attachable ladders shall have a minimum rung length of 11 1/2 inches.
• Hook-on and attachable ladders shall have uniformly spaced rungs with a maximum spacing between rungs of 16 3/4 inches.
• Stairway-type ladders shall:

(1) Be positioned such that their bottom step is not more than 24 inches above the scaffold supporting level.
(2) Be provided with rest platforms at 12 foot maximum vertical intervals.
(3) Have a minimum step width of 16 inches except that mobile scaffolds stairway type ladders shall have a minimum step width of 11 1/2 inches.
(4)Have slip-resistant treads on all steps and landings.

• Stairtowers, shall be positioned such that their bottom step is not more than 24 inches above the scaffold supporting level.
• A stairrail consisting of a toprail and a midrail shall be provided on each side of each scaffold stairway
• The toprail of each stairrail system shall also be capable of serving as a handrail, unless a separate handrail is provided.
• Each Handrails, and toprails that serve as handrails, shall provide an adequate handhold for employees grasping them to avoid falling.
• Stairrail systems and handrails shall be surfaced to prevent injury to employees from punctures or laceration, and to prevent snagging of clothing.
• The ends of stairrail systems and handrails shall be constructed so that they do no constitute a projection hazard.
• Handrails, and toprails that are used as handrails, shall be at least 3 inches from other objects.
• Stairrails shall not be less than 28 inches nor more than 37 inches from the upper surface of the stairrail to the surface of the tread, in line with the face of the riser at the forward edge of the tread.
• A landing platform at least 18 inches wide by at least 18 inches long shall be provided at each level.
• Each scaffold stairway shall be at least 18 inches between stairrails.
• Treads and landings shall have slip-resistant surfaces.
• Stairways shall be installed between 40 degrees and 60 degrees from horizontal.
• Guardrails meeting the standards requirements shall be provided on the open sides and ends of each landing.
• Riser heights shall be uniform, within 1/4 inch, for each flight of stairs.
• Tread depth shall be uniform, within 1/4 inch, for each flight of stairs.
• Ramps and walkways 6 feet or more above lower levels shall have guardrails systems which comply with Subpart M- Fall Protection:
• No ramp or walkway shall be inclined more than a slope of one (1) vertical to three (3) horizontal (20 degree above horizontal).
• If the slope of a ramp or a walkway is steeper than one (1) vertical in eight (8) horizontal, the ramp or walkway shall have cleats not more than fourteen (14) inches apart which are securely fastened to the planks to provide footing.
• Integral prefabricated scaffold access frames shall:
• Be specifically designed and constructed for use as ladder rungs.
• Have a rung length of a least 8 inches.
• Not be used as work platforms when rungs are less than II 1/2 inches in length, unless affected employee uses fall protection, or a positioning device, which complies with 1926.502.
• Be uniformly spaced within each frame section.
• Be provided with rest platforms at 35-foot maximum vertical intervals on all supported scaffolds more than 3 5 feet high.
• Have a maximum spacing between rungs of 16 3/4 inches. Non-uniform rung spacing caused by joining end frames together is allowed, provided the resulting spacing does not exceed 16 3/4 inches.
• Steps and rungs of ladder and stairway type access shall line up vertically with each other between rest platforms.
• Direct access to or from another surface shall be used only when the scaffold is not more than 14 inches horizontally and not more than 24 inches vertically from the other surface.
• Effective August 30, 1997, access for employees erecting and dismantling supported scaffolds shall be in accordance with the following:
• The employer shall provide safe means of access for each employee erecting or dismantling a scaffold where the provision of safe access is feasible and does not create a greater hazard. The employer shall have a competent person determine whether it is feasible or would pose a greater a hazard to provide, and have employees use a safe means of access. This determination shall be based on site conditions and the type of scaffold being erected or dismantled.
• Hook-on or attachable ladders shall be installed as soon as scaffold erection has progressed to a point that permits safe installation and use.
• When erecting or dismantling tubular welded frame scaffolds, (end) frames with horizontal members that are parallel, level and are not more than 22 inches apart vertically may be used as climbing devices for access, provided they are erected in a manner that creates a usable ladder and provides good hand hold and foot space.
• Cross braces on tubular welded frame scaffolds shall not be used as a means of access or egress.

(f) Use.

• Scaffolds and scaffolds components shall not be loaded in excess of their maximum intended loads or rated capacities, whichever is less.
• The use of shore or lean-to scaffolds is prohibited.
• Scaffolds and scaffold components shall be inspected for visible defects be a competent person before each work shift, and after any occurrence which could affect a scaffold's structural integrity.
• Any part of a scaffold damaged or weakened so that its strength is less than that required by this standard shall be immediately repaired or replaced, braced to meet those provisions, or removed from service until repaired.
• Scaffolds shall not be move horizontally while employees are on them, unless they have been designed by a registered professional engineer specifically for such movement or, for mobile scaffolds, where the provisions of 1926.452(w) are followed.
• The clearance between scaffolds and power lines shall be as follows: Scaffolds shall not be erected, used dismantled, altered, or moved such that they or any conductive material handled on them might get closer to exposed and energized lines than as follows:

INSULATED LINES

Less than 300 volts Minimum Distance 3 feet

330 volts to 50kv Minimum Distance 10 feet

More than 50kv Minimum Distance 10 feet plus 4 inches for each 1kv over 50kv or

2 times the length of the line insulator, but never less than 10 feet

UNINSULATED LINES

Less than 50 kv Minimum Distance 10 feet

More than 50kv Minimum Distance 10 feet plus 4 inches for each 1kv over 50kv or

2 times the length of the line insulator, but never less than 10 feet

• Scaffolds shall be erected, moved, dismantled, or altered only under the supervision and direction of a competent person qualified is scaffold erection, moving, dismantling or alteration. Such activities shall be performed only by experienced and trained employees selected for such work by the competent person.
• Employees shall be prohibited from working on scaffolds with snow, ice, or other slippery material except as necessary for removal of such materials.
• Where swinging loads are being hoisted onto or near scaffolds such that the loads might contact the scaffold, tag lines or equivalent measures to control the loads shall be used.
• Suspension ropes supporting adjustable suspension scaffolds shall be of a diameter large enough to provide sufficient surface area for the functioning of brake and hoist mechanisms.
• Suspension ropes shall be shielded from heat-producing processes. When acids or other corrosive substances are used on a scaffold, the ropes shall be shielded, treated to protect against the corrosive substances, or shall be of a material that will not be damaged by the substance being used.
• Work on or from scaffolds is prohibited during storms or high winds unless a competent person has determined that it is safe for employees to be on the scaffold and those employees are protected by a personal fall arrest system or wind screens. Wind screens shall not be used unless the scaffold is secured against the anticipated wind forces imposed.
• Debris shall not be allowed to accumulate on platforms.
• Makeshift devices, such as but not limited to boxes and barrels, shall not be used on top of scaffold platforms to increase the working level height of employees.
• Ladders shall not be used on scaffolds to increase the working level height of employees, except on large area scaffolds where employees have satisfied the following criteria:
• When the ladder is placed against a structure which is not part of the scaffold, the scaffold shall be secured against the sideways thrust exerted by the ladder.
• The platform units shall be secured to the scaffold to prevent their movement.
• The ladder legs shall be on the same platform or other means shall be provided to stabilize the ladder against unequal platform deflection.movement.movement.
• The ladder legs shall be secured to prevent them from slipping or being pushed off the platform.
• Platform shall not deflect more than 1/60 of the span when loaded
• To reduce the possibility of welding current arcing through the suspension wire ropes when performing welding from suspension scaffolds the following precautions shall be taken, as applicable:
• An insulated thimble shall be used to attach each suspension wire rope to its hanging support. Excess suspension wire rope and any additional lines independent lines from grounding shall be insulated.
• The suspension wire rope shall be covered with insulating material extending at least 4 feet above the hoist.
• Each hoist line shall be covered with insulated protective covers.
• In addition to a work lead attachment required by the welding process, a grounding conductor shall be connected from the scaffold to the structure.
• If the scaffold grounding lead is disconnected at any time, the welding shall be shut off.
• An active welding rod or UNINSULATED welding lead shall not be allowed to contact the scaffold or its suspension system.

(g) Fall protection.

• Each employee on a scaffold more than IO feet above a lower level shall be protected from falling to that lower level.
• The employer shall have a competent person determine the feasibility and safety of providing fall protection for employees erecting or dismantling supported scaffolds. Employers are required to provide fall protection for employees erecting or dismantling supported scaffolds where the installation and use of such protection is feasible and does not create a greater hazard.
• Personal fall arrest systems used on scaffolds shall be attached by a lanyard to a vertical lifeline, horizontal lifeline, or scaffold structural member.
• Guardrail systems installed to meet the requirements of the section shall comply with the following provisions:
• Guardrail systems shall be installed along all open sides and ends of platforms.
• Guardrail systems shall be installed before the scaffold is released for use by employees other than erection/dismantling crews.
• The top edge height of toprails or equivalent member on supported scaffolds manufactured or placed in service after January 1, 2000 shall be installed between 38 inches and 45 inches above the platform surface. The top edge height on supported scaffolds manufactured and placed in service before January 1, 2000, and on all suspended scaffolds where both a guardrail and a personal fall arrest system are required shall be between 36 and 45 inches.
• When midrails, screens, mesh, intermediate vertical members, solid panels, or equivalent structural members are used, they shall be installed between the top edge of the guardrail system and the scaffold platform.
• When midrails are used, they shall be installed at a height approximately midway between the top edge of the guardrail system and the platform surface.
• When screens and mesh are used, they shall extend from the top edge of the guardrail system to the scaffold platform, and along the entire opening between the supports.
• When intermediate members are used, they shall not be more than 19 inches apart.
• Each toprail or equivalent member of a guardrail system shall be capable of withstanding, without failure, a force applied in any downward or horizontal direction at any point along its top edge of a least I 00 pounds for guardrail systems installed on single-point adjustable suspension scaffolds or two-point adjustable suspension scaffolds, and at least 200 pounds for guardrails systems installed on all other scaffolds.
• When loads specified in the (g)(4)(vii) are applied direction, the top edge shall not be below the height above the platform that is prescribed in paragraph (g)(4)(ii).
• Midrails, screens, mesh, intermediate vertical members, solid panels, and equivalent structural members of a guardrail system shall be capable of withstanding, without failure, a force applied in any downward or horizontal direction at any point along the midrail or other member of at least 75 for guardrail systems with a minimum 1 00 pound toprail capacity, and at least 150 pounds for a guardrail system with a minimum 200 pound toprail capacity.
• Suspension scaffolds hoists and non-walk-through stirrups may be used as end guardrails, if the space between the hoist or stirrup and the side guardrail or structure does not allow passage of an employee to the end of the scaffold.
• Guardrails shall be surfaced to prevent injury to an employee from punctures or lacerations, and to prevent snagging of clothing.
• The ends of all rails shall not overhang the terminal posts except when such overhang does not constitute a projection hazard to employees.
• Steel or plastic banding shall not be used as a toprail or midrail.
• Manila or plastic rope being used for toprails or midrails shall be inspected by a competent person as frequently as necessary to ensure that it continues to meet the strength requirements of paragraph (g) of this section.
• Cross bracing is acceptable in the place of a midrail when the crossing point of the two braces is between 20 inches and 30 inches above the work platform or as a toprail when the crossing point of the two braces is between 38 inches and 48 inches above the work platform. The end points at each upright shall be no more than 48 inches apart.

(h) Falling object protection.