W. Va. Code R. § 36-23-33

Current through Register Vol. XLI, No. 24, June 14, 2024

Section 36-23-33 - Ladders and Scaffolding

33.1. Ladders.

(a) General requirements.

(1) Except where either permanent or temporary stairways or suitable ramps or runways are provided, ladders described in this subpart shall be used to give safe access to all elevations. All ladders shall be inspected by a competent person before each use. Ladders with defects shall be removed from service.

(2) The use of ladders with broken or missing rungs or steps, broken or split side rails, or other faulty or defective construction is prohibited.

When ladders with such defects are discovered, they shall be immediately withdrawn from service. Inspection of metal ladders shall include checking for corrosion of interiors or open end hollow rungs.

(3) Manufactured portable wood ladders provided by the employer shall be in accordance with the provisions of the ANSI A14.1-1968, Safety Code for portable wood ladders.

(4) Portable metal ladders shall be of strength equivalent to that of wood ladders. Manufactured portable metal ladders provided by the employer shall be in accordance with the provisions of the ANSI, A14.2-1956, Safety Code for portable metal ladders.

(5) Fixed ladders shall be in accordance with the provisions of the American National Standards Institute A14.3-1956, Safety Code for fixed ladders.

(6) Portable ladder feet shall be placed on a substantial base, and the area around the top and bottom of the ladder shall be kept clear.

(7) Portable ladders shall be used at such a pitch that the horizontal distance from the top support to the foot of the ladder is about one-quarter of the working length of the ladder (the length along the ladder between the foot and the top support.) Ladders shall not be used in a horizontal position as platforms, runways, or scaffolds.

(8) Ladders shall not be placed in passageways, doorways, driveways, or any location where they may be displaced by activities being conducted on any work, unless protected by barricades or guards.

(9) The side rails shall extend not less than thirty-six (36) inches above the landing. When this is not practical, grab rails, which provide a secure grip for an employee moving to or from the point of access, shall be installed.

(10) Portable ladders in use shall be tied, blocked, or otherwise secured to prevent their being displaced.

(11) Portable metal ladders shall not be used for electrical work or where they may contact electrical conductors.

(b) Job-made ladders.

(1) Job-made ladders shall be constructed for intended use. If a ladder is to provide the only means of access or exit from a working area for twenty-five (25) or more employees, or simultaneous two (2)-way traffic is expected, a double cleat ladder shall be installed.

(2) Double cleat ladders shall not exceed twenty-four (24) feet in length.

(3) Single cleat ladders shall not exceed thirty (30) feet in length between supports (base and top landing). If ladders are to connect different landings, or if the length required exceeds this maximum length, two (2) or more separate ladders shall be used, offset with a platform between each ladder. Guardrails and toeboards shall be erected on exposed sides of the platforms.

(4) The width of single cleat ladders shall be at least fifteen (15) inches, but not more than twenty (20) inches, between rails at the top.

(5) Side rails shall be parallel or flared top to bottom by not more than onequarter (1/4) of an inch for each two (2) feet of length.

(6) Wood side rails of ladders having cleats shall be not less than one and one-half (1 1/2) inches thick and three and one-half (3 1/2) inches deep (two (2) inches x four (4) inches nominal) when made of Group 2 or Group 3 woods (see Table 27) may be used in the same cross-section of dimensions for cleat ladders up to twenty (20) feet in length.

(7) It is preferable that side rails be continuous. If splicing is necessary to attain the required length, however, the splice must develop the full strength of a continuous side rail of the same length.

(8) Two (2) inch x four (4) inch lumber shall be used for side rails of single cleat ladders up to sixteen (16) feet long; three (3) inch x six (6) inch lumber shall be used for single cleat ladders from sixteen (16) to thirty (30) feet in length.

(9) Two (2) inch x four (4) inch lumber shall be used for side and middle rails of double cleat ladders up to twelve (12) feet in length; two (2) inch x six (6) inch lumber four double cleat ladders from twelve (12) to twenty-four (24) feet in length.

(10) Wood cleats shall have the following minimum dimensions when made of Group 1 woods, (see Table 28):

(11) Cleats may be made of species of any other group of wood (see Table 27) provided equal or greater strength is maintained.

(12) Cleats shall be inset into the edges of the side rails one-half (1/2) inch, or filler blocks shall be used on the rails between the cleats. The cleats shall be secured to each rail with three (3) ten (10)d common wire nails or other fasteners of equivalent strength. Cleats shall be uniformly spaced, twelve (12) inches top-to-top.

33.2. Scaffolding.

(a) General requirements.

(1) Scaffolds shall be erected in accordance with requirements of this section. All scaffolding shall be inspected prior to each use and scaffolding found defective of improper type or not properly constructed will not be used until corrected. Scaffolding shall be inspected for dry rot, cracks or other defects prior to construction of a scaffold. Scaffold planks shall be inspected as to the above mentioned. Defective planks shall be removed from service.

(2) The footing or anchorage for scaffolds shall be sound, rigid, and capable of carrying the maximum intended load without settling or displacement. Unstable objects such as barrels, boxes, loose brick, or concrete blocks, shall not be used to support scaffolds or planks.

(3) No scaffold shall be erected, moved, dismantled, or altered except under the supervision of competent persons.

(4) Guardrails and toeboards shall be installed on all open sides and ends of platforms more than ten (10) feet above the ground or floor, except needle beam scaffolds and floats. Scaffolds four (4) feet to ten (10) feet in height, having a minimum horizontal dimension in either direction of less than forty-five (45) inches, shall have standard guardrails installed on all open sides and ends of the platform.

(5) Guardrails shall be two (2) inches x four (4) inches, or the equivalent, approximately forty-two (42) inches high, with a midrail, when required. Supports shall be at intervals not to exceed eight (8) feet. Toeboards shall be a minimum of four (4) inches in height.

(6) Where persons are required to work or pass under the scaffold, scaffolds shall be provided with a screen between the toeboard and the guardrail, extending along the entire opening, consisting of the No. 18 gauge wire, one and one-half (1 1/2) inch mesh, or the equivalent.

(7) Scaffolds and their components shall be capable of supporting without failure at least four (4) times the maximum intended load.

(8) Any scaffold including accessories such as braces, brackets, trusses, screw legs, ladders, etc., damaged or weakened from any cause shall be immediately repaired or replaced.

(9) All load-carrying timber members of scaffold framing shall be a minimum of one thousand five hundred (1,500) fiber construction grade lumber. All dimensions are nominal sizes, except that where rough sizes are noted, only rough or undressed lumber of the size specified will satisfy minimum requirements.

(10) All planking shall be scaffold grades, or equivalent, as recognized by approved grading rules for the species of wood used. The maximum permissible spans for two (2-) x ten (10)-inch or wider planks shall be as shown in Table 29:

(11) The maximum permissible span for one and one-quarter (1 1/4) inch x nine (9) inch or wider plank of full thickness shall be four (4) feet with medium duty loading of fifty (50) p.s.f.

(12) All planking or platforms shall be overlapped (minimum twelve (12) inches), or secured from movement.

(13) An access ladder or equivalent safe access shall be provided.

(14) Scaffold planks shall extend over their end supports not less than six (6) inches nor more than twelve (12) inches.

(15) The poles, legs, or uprights of scaffolds shall be plumb, and securely and rigidly braced to prevent swaying and displacement.

(16) Overhead protection shall be provided for men on a scaffold exposed to overhead hazards.

(17) Slippery conditions on scaffolds shall be eliminated as soon as possible after they occur.

(18) No welding, burning, riveting, or open flame work shall be performed on any staging suspended means of fiber or synthetic rope. Only treated or protected fiber or synthetic ropes shall be used for or near any work involving the use of corrosive substances or chemicals.

(19) Wire, synthetic, or fiber rope used for scaffold suspension shall be capable of supporting at least six (6) times the rated load.

(20) The use of shore or lean-to scaffolds is prohibited.

(21) Lumber sizes, when used in this subpart, refer to nominal sizes except where otherwise stated.

(b) Wood pole scaffolds.

(1) Scaffold poles shall bear on a foundation of sufficient size and strength to spread the load from the pole over a sufficient area to prevent settlement. All poles shall be set plumb.

(2) Where wood poles are spliced, the ends shall be squared and the upper section shall rest squarely on the lower section. Wood splice plates shall be provided on at least two (2) adjacent sides and shall be not less than four (4) feet in length, overlapping the abutted ends equally, and have the same width and not less than the cross sectional area of the pole. Splice plates or other materials of equivalent strength may be used.

(3) Independent pole scaffolds shall be set as near to the wall of the building as practicable.

(4) All pole scaffolds shall be securely guyed or tied to the building or structure. Where the height or length exceeds twenty-five (25) feet, the scaffold shall be secured at intervals not greater than twentyfive (25) feet vertically and horizontally.

(5) Putlogs or bearers shall be set with their greater dimension vertical, long enough to project over the ledgers of the inner and outer rows of poles at least three (3) inches for proper support.

(6) Every wooden putlog on single pole scaffolds shall be reinforced with three-sixteenths (3/16) inch x two (2) inch steel strip, or equivalent, secured to its lower edge throughout its entire length.

(7) Ledgers shall be long enough to extend over two (2) pole spaces. Ledgers shall not be spliced between the poles. Ledgers shall be reinforced by bearing blocks securely nailed to the side of the pole to form a support for the ledger.

(8) Diagonal bracing shall be provided to prevent the poles from moving in a direction parallel with the wall of the building, or from buckling.

(9) Cross bracing shall be provided between the inner and outer sets of poles in independent pole scaffolds. The free ends of pole scaffolds shall be cross braced.

(10) Full diagonal face bracing shall be erected across the entire face of pole scaffolds in both directions. The braces shall be spliced at the poles. The inner row of poles on medium and heavy duty scaffolds shall be braced in a similar manner.

(11) Platform plank shall be laid with their edges close together so the platform will be tight with no spaces through which tools or fragments of material can fall.

(12) Where planking is lapped, each plank shall lap its end supports at least twelve (12) inches. Where the ends of planks abut each other to form a flush floor, the butt joint shall be at the centerline of a pole. The abutted ends shall rest on separate bearers. Intermediate beams shall be provided where necessary to prevent dislodgement of plants due to deflection, and the ends shall be secured to prevent their dislodgement.

(13) When a scaffold materially changes its direction, the platform planks shall be laid to prevent tipping. The planks that meet the corner putlog at an angle shall be laid first, extending over the diagonally placed putlog far enough to have a good safe bearing, but not far enough to involve any danger from tipping. The planking running in the opposite direction at an angle shall be laid so as to extend over and rest on the first layer of planking.

(14) When moving platforms to the next level, the old platform shall be left undisturbed until the new putlogs or bearers have been set in place, ready to receive the platform planks.

(15) Guardrails, made of lumber not less than two (2) inches x four (4) inches (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section, when required.

(16) All wood pole scaffolds sixty (60) feet or less in height shall be constructed and erected in accordance with Table 30 through 36. If they are over sixty (60) feet in height, they shall be designed by a qualified engineer competent in this field, and it shall be constructed and erected in accordance with such design.

(c) Tube and coupler scaffolds.

(1) A light duty tube and coupler scaffold shall have all posts, bearers, runners, and bracing of nominal two (2) inch O. D. steel tubing. The posts shall be spaced no more than six (6) feet apart by ten (10) feet along the length of the scaffold. Other structural metals when used must be designed to carry an equivalent load. No dissimilar metals shall be used together.

(2) A medium duty tube and coupler scaffold shall have all posts, runners, and bracing of nominal two (2) inch O. D. steel tubing. Posts spaced not more than five (5) feet apart by eight (8) feet along the length of the scaffold shall have bearers of nominal two (2) inch O. D. steel tubing.

Other structural metals, when used, must be designed to carry an equivalent load. No dissimilar metals shall be used together.

(3) A heavy duty tube and coupler scaffold shall have all posts, runners, and bracing of nominal two (2) inch O. D. steel tubing, with the posts spaced not more than six (6) feet x six (6) feet six (6) inches. Other structural metals, when used, must be designed to carry an equivalent load. No dissimilar metals shall be used together.

(4) Tube and coupler scaffolds shall be limited in heights and working levels to those permitted in Tables 36, 37 and 38. Drawings and specifications of all tube and coupler scaffolds above the limitations in Tables 36, 37 and 38 shall be designed by a qualified engineer competent in this field.

(5) All tube and coupler scaffolds shall be constructed and erected to support four (4) times the maximum intended loads, as set forth in Tables 36, 37 and 38, or as set forth in the specifications by a licensed professional engineer competent in this field.

(6) Posts shall be accurately spaced, erected on suitable bases, and maintained plumb.

(7) Runners shall be erected along the length of the scaffold, located on both the inside and the outside posts at even height. Runners shall be interlocked to form continuous lengths and coupled to each post. The bottom runners shall be located as close to the base as possible. Runners shall be placed not more than six (6) feet six (6) inches on centers.

(8) Bearers shall be installed transversely between posts and shall be securely coupled to the posts bearing on the runner coupler. When coupled directly to the runners, the coupler must be kept as close to the posts as possible.

(9) Bearers shall be at least four (4) inches but not more than twelve (12) inches longer than the post spacing or runner spacing.

(10) Cross bracing shall be installed across the width of the scaffold at least every third set of posts horizontally and every fourth runner vertically. Such bracing shall extend diagonally from the inner and outer runners upward to the next outer and inner runners.

(11) Longitudinal diagonal bracing on the inner and outer rows of poles shall be installed at approximately a forty-five (45) degree angle from near the base of the first outer post upward to the extreme top of the scaffold. Where the longitudinal length of the scaffold permits, such bracing shall be duplicated beginning at every fifth post. In a similar manner, longitudinal diagonal bracing shall also be installed from the last post extending back and upward toward the first post. Where conditions preclude the attachment of this bracing to the posts, it may be attached to the runners.

(12) The entire scaffold shall be tied to and securely braced against the building at intervals not to exceed thirty (30) feet horizontally and twenty-six (26) feet vertically.

(13) Guardrails, made of lumber not less than two (2) inches x four (4) inches (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboard shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(d) Tubular welded frame scaffolds.

(1) Metal tubular frame scaffolds including accessories such as braces, brackets, trusses, screw legs, ladders, etc., shall be designed, constructed, and erected to safely support four (4) times the maximum rated load.

(2) Spacing of panels or frames shall be consistent with the loads imposed.

(3) Scaffolds shall be properly braced by cross bracing or diagonal braces, or both, for securing vertical members together laterally, and the cross braces shall be of such length as will automatically square and align vertical members so that the erected scaffold is always plumb, square, and rigid. All brace connections shall be made secure.

(4) Scaffold legs shall be set on adjustable bases or plain bases placed on mud sills or other foundations adequate to support the maximum rated load.

(5) The frames shall be placed one (1) on top of the other with coupling or stacking pins to provide proper vertical alignment of the legs.

(6) Where uplift may occur, panels shall be locked together vertically by pins or other equivalent suitable means.

(7) To prevent movement, the scaffold shall be secured to the building or structure at intervals not to exceed thirty (30) feet horizontally and twenty-six (26) feet vertically.

(8) Maximum permissible spans or planking shall be in conformity with paragraph (a)(10) of this section.

(9) Drawings and specifications for all frame scaffolds over one hundred twenty-five (125) feet in height above the base plates shall be designed by a registered professional engineer.

(10) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), and approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(e) Manually propelled mobile scaffolds.

(1) When free-standing mobile scaffold towers are used, the height shall not exceed four (4) times the minimum base dimension.

(2) Casters shall be properly designed for strength and dimensions to support four (4) times the maximum intended load. All casters shall be provided with a positive locking device to hold the scaffold in position.

(3) Scaffolds shall be properly braced by cross bracing and horizontal bracing conforming with paragraph (d)(3) of this section.

(4) Platforms shall be tightly planked for the full width of the scaffold except for necessary entrance opening. Platforms shall be secured in place.

(5) A ladder or stairway shall be provided for proper access and exit and shall be affixed or built into the scaffold and so located that when in use it will not have a tendency to tip the scaffold. A landing platform must be provided at intervals not to exceed thirty-five (35) feet.

(6) The force necessary to move the mobile scaffold shall be applied near or as close to the base as practicable and provision shall be made to stabilize the tower during movement from one (1) location to another. Scaffolds shall only be moved on level floors, free of obstructions and openings.

(7) The employer shall not allow employees to ride on manually propelled scaffolds unless the following conditions exist:

(i) The floor or surface is within three (3) degrees of level, and free from pits, holes, or obstructions;

(ii) The minimum dimension of the scaffold base when ready for rolling, is at least one-half (1/2) the height. Outriggers, if used, shall be installed on both sides of staging;

(iii) The wheels are equipped with rubber or similar resilient tires;

(iv) All tools and materials are secured or removed from the platform before the mobile scaffold is moved.

(8) Scaffolds in use by any person shall rest upon a suitable footing and shall stand plumb. The casters or wheels shall be locked to prevent any movement.

(9) Mobile scaffolds constructed of metal members shall also conform to applicable provisions of paragraphs (b), (c), or (d) of this section, depending on the material of which they are constructed.

(10) Guardrails of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(f) Outrigger scaffolds.

(1) Outrigger beams shall extend not more than six (6) feet beyond the face of the building. The inboard end of outrigger beams, measured from the fulcrum point to anchorage point, shall be not less than one and one-half (1 1/2) time the outboard end in length. The beams shall rest on edge, the sides shall be plumb, and the edges shall be horizontal. The fulcrum point of the beam shall rest on a secure bearing at least six (6) inches in each horizontal dimension. The beam shall be secured in place against movement and shall be securely braced at the fulcrum point against tipping.

(2) The inboard ends of outrigger beams shall be securely anchored either by means of struts bearing against sills in contact with the overhead beams or ceiling, or by means of tension members secured to the floor joints underfoot, or by both if necessary. The inboard ends of outrigger beams shall be secured against tipping and the entire supporting structure shall be securely braced in both directions to prevent any horizontal movement.

(3) Unless outrigger scaffolds are designed by a registered professional engineer competent in this field, they shall be constructed and erected in accordance with Table 39. Outrigger scaffolds, designed by a registered professional engineer, shall be constructed and erected in accordance with such design.

(4) Planking shall be laid tight and shall extend to within three (3) inches of the building wall. Planking shall be secured to the beams.

(5) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(h) Masons' adjustable multiple-point suspension scaffolds.

(1) The scaffold shall be capable of sustaining a working load of fifty (50) pounds per square foot and shall not be loaded in excess of that figure.

(2) The scaffold shall be provided with hoisting machines that meet the requirements of underwriters laboratories of factory mutual engineering corporation.

(3) The platform shall be supported by wire ropes, capable of supporting at least six (6) times the intended load, suspended from overhead outrigger beams.

(4) The scaffold outrigger beams shall consist of structural metal securely fastened or anchored to the frame or floor system of the building or structure.

(5) Each outrigger beam shall be equivalent in strength to at least a standard seven (7) inch, fifteen and three-tenths (15.3) lb. steel I-beam, at least fifteen (15) feet long, and shall not project more than six (6) feet six (6) inch beyond the bearing point.

(6) Where the overhand exceeds six (6) feet six (6) inches, outrigger beams shall be composed of stronger beams or multiple beams and be installed under the supervision of a competent person.

(7) All outrigger beams shall be set and maintained with their webs in a vertical position.

(8) A stop bolt shall be placed at each end of every outrigger beam.

(9) The outrigger beam shall rest on suitable wood bearing blocks.

(10) The free end of the suspension wire ropes shall be equipped with proper size thimbles and secured by splicing or other equivalent means. The running ends shall be securely attached to the hoisting drum and at least four (4) turns of wire rope shall at all times remain on the drum. The use of fiber rope is prohibited.

(11) Where a single outrigger beam is used, the steel shackles or clevises with which the wire ropes are attached to the outrigger beams shall be placed directly over the hoisting drums.

(12) The scaffold platform shall be equivalent in strength to at least two (2) inches planking. (For maximum planking spans, see paragraph (a)(11) of this section.)

(13) When employees are at work on the scaffold and an overhead hazard exists, overhead protection shall be provided on the scaffold, not more than nine (9) feet above the platform, consisting of two (2) inch planking, or material of equivalent strength, laid tight, and extending not less than the width of the scaffold.

(14) Each scaffold shall be installed or relocated under the supervision of a competent person.

(15) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail, and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(i) (Swinging scaffolds) Two (2) point suspension.

(1) Two (2) point suspension scaffold platforms shall be not less than twenty (20) inches nor more than thirty-six (36) inches wide overall. The platform shall be securely fastened to the hangers by U-bolts or by other equivalent means.

(2) The hangers of two (2) point suspension scaffolds shall be made of mild steel, or other equivalent materials, having a cross-sectional area capable of sustaining four (4) times the maximum rated load, and shall be designed with a support for guardrail, intermediate rail, and toeboard.

(3) When hoisting machines are used on two (2) point suspension scaffolds, such machines shall be of a design tested and approved by Underwriters Laboratories of Factory Mutual Engineering Corporation.

(4) The roof irons or hooks shall be of mild steel, or other equivalent material, of proper size and design, securely installed and anchored. Tiebacks of three-quarter (3/4) inch manila rope, or the equivalent, shall serve as a secondary means of anchorage, installed at right angles to the face of the building, whenever possible, and secured to a structurally sound portion of the building.

(5) Two-point suspension scaffolds shall be suspended by wire, synthetic or fiber ropes capable of supporting at least six (6) times the rated load. All other components shall be capable of supporting at least four (4) times the rated load.

(6) The sheaves of all blocks, consisting of at least one (1) double and one (1) single block, shall fit the size and type of rope used.

(7) All wire ropes, fiber and synthetic ropes, slings, hangers, platforms, and other supporting parts shall be inspected before every installation. Periodic inspections shall be made while the scaffold is in use.

(8) On suspension scaffolds designed for a working load of five hundred (500) pounds, no more than two (2) men shall be permitted to work at one time. On suspension scaffolds with a working load of seven hundred fifty (750) pounds, no more than three (3) men shall be permitted to work at one time. Each employee shall be protected by an approved safety life belt attached to a lifeline. The lifeline shall be securely attached to substantial members of the structure (not scaffold), or to securely rigged lines which will safely suspend the employee in case of a fall. In order to keep the lifeline continuously attached, with a minimum of slack, to a fixed structure, the attachment point of the lifeline shall be appropriately changed as the work progresses.

(9) Two (2) point suspension scaffolds shall be securely lashed to the building or structure to prevent them from swaying. Window cleaners' anchors shall not be used for this purpose.

(10) The platform of every two (2) point suspension scaffold shall be one of the following types:

(i) Ladder-type platforms. The side stringer shall be of clear straightgrained spruce or materials of equivalent strength and durability. The rungs shall be of straight-grained oak, ash, or hickory, at least one and one-eighth (1 1/8) inch in diameter, with seven-eighths (7/8) inch. The stringers shall be tied together with tie rods not less than one-quarter (1/4) 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 fiveeighths (5/8) inch apart except at the side rails where the space may be one (1) inch. Ladder-type platforms shall be constructed in accordance with Table 40.

(ii) Plank-type platforms. Plank-type platforms shall be composed of not less than nominal two (2) inch x ten (10) inch unspliced planks, properly cleated together on the underside, starting six (6) inches from each end; intervals in between shall not exceed four (4) feet. The plank-type platform shall not extend beyond the hangers more than twelve (12) inches. A bar or other effective means shall be securely fastened to the platform at each end to prevent its slipping off the hanger. The span between hangers for plank-type platforms shall not exceed eight (8) feet.

(iii) Beam-type platforms. Beam platforms shall have side stringers of lumber not less than two (2) inch x six (6) inch set on edge. The span between hangers shall not exceed twelve (12) feet when beam platforms are used. The flooring shall be supported on two (2) inch x six (6) inch cross beams, laid flat and set into the upper edge of the stringers with a snug fit, at intervals of not more than four (4) feet, securely nailed in place. The flooring shall be of one (2) inch x six (6) inch material properly nailed. Floor board shall not be spaced more than one-half (1/2) inch apart.

(iv) Light metal-type platforms, when used, shall be tested and listed according to Underwriters Laboratories of Factory Mutual Engineering Corporation.

(11) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail, and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(j) Stone setters' adjustable multiple-point suspension scaffolds.

(1) The scaffold shall be capable of sustaining a working load of twenty-five (25) pounds per square foot and shall not be used for storage of stone or other heavy materials.

(2) When used, the hoisting machine and its supports shall be of a type tested and listed by Underwriters Laboratories of Factory Mutual Engineering Corporation.

(3) The platform shall be securely fastened to the hangers of U-bolts or other equivalent means. (For materials and spans, see subdivision (ii) of paragraph (i)(10), plank-type platforms, and Table 40 of this section.)

(4) The scaffold unit shall be suspended from metal outriggers, from brackets, wire rope slings, or iron hooks.

(5) Outriggers, when used, shall be set with their webs in a vertical position, securely anchored to the building or structure and provided with stop bolts at each end.

(6) The scaffold shall be supported by wire rope capable of supporting at least six (6) times the rated load. All other components shall be capable of supporting at least four (4) times the rated load.

(7) The free ends of the suspension wire ropes shall be equipped with proper size thimbles, secured by splicing or other equivalent means. The running ends shall be securely attached to the hoisting drum and at least four (4) turns of wire rope shall remain at the drum at all times.

(8) When two (2) or more scaffolds are used on a building or structure, they shall not be bridged one to the other, but shall be maintained at even height with the platforms abutting closely.

(9) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail, and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(k) Single-point adjustable suspension scaffolds.

(1) The scaffolding, including power units or manually operated winches, shall be of a type tested and listed by Underwriters Laboratories of Factory Mutual Engineering Corporation.

(2) The power units may be either electrically or air motor driven.

(3) All power-operated gears and brakes shall be enclosed.

(4) In addition to the normal operating brake, all power-driven units shall have an emergency brake which engages automatically when the normal speed of descent is exceeded.

(5) The hoisting machines, cables, and equipment shall be regularly serviced and inspected.

(6) The units may be combined to form a two (2) point suspension scaffold. Such scaffold shall then comply with paragraph (i) of this section.

(7) The supporting cable shall be vertical for its entire length, and the basket shall not be swayed nor the cable fixed to any intermediate points to change the original path of travel.

(8) Suspension methods shall conform to applicable provisions of paragraphs (h) and (i) of this section.

(9) Guards, midrails, and toeboards shall completely enclose the cage or basket. Guardrails shall be no less than two (2) inch x four (4) inch or the equivalent, approximately forty-two (42) inches above the platform. Midrails shall be one (1) inch x six (6) inch or the equivalent, installed equidistant between the guardrail and platform. Toeboards shall be a minimum of four (4) inches in height.

(10) For additional details not covered in this paragraph, applicable technical portions of American National Standards Institute A120.1-1970, power operated devices for exterior building maintenance powered platforms, shall be used.

(l) Boatswain's chairs.

(1) The chair seat shall not be less than twelve (12) inch x twenty-four (24) inch, and one (1) inch thickness. The seat shall be reinforced on the underside by cleats securely fastened to prevent the board from splitting.

(2) The two (2) fiber rope seat slings shall be of five-eighths (5/8) inch diameter, reeved through the four (4) seat holes so as to cross each other on the underside of the seat.

(3) Seat slings shall be of at least three-eighths (3/8) inch wire rope when an employee is conducting a heat-producing process, such as gas or arc welding.

(4) The employee shall be protected by a safety belt and lifeline.

The attachment point of the lifeline to the structure shall be appropriately changed as the work progresses.

(5) The tackle shall consist of correct size ball bearing or brushed blocks and properly spliced five-eighths (5/8) inch diameter first-grade manila rope, or equivalent.

(6) The roof irons, hoods, or the object to which the tackle is anchored, shall be securely installed. Tiebacks, when used, shall be installed at right angles to the face of the building and securely fastened.

(m) Carpenters' bracket scaffolds.

(1) The brackets shall consist of a triangular wood frame not less than two (2) inch x three (3) inch in cross section, or of metal of equivalent strength. Each member shall be properly fitted and securely joined.

(2) Each bracket shall be attached to the structure by means of one (1) of the following:

(i) A bolt, no less than five-eighths (5/8) inches in diameter, which shall extend through to the inside of the building wall;

(ii) A metal stud attachment device;

(iii) Welding to steel tanks;

(iv) Hooking over a well-secured and adequately strong supporting member.

(3) The brackets shall be spaced no more than eight (8) feet apart.

(4) No more than two (2) employees shall occupy any given eight (8) feet of a bracket scaffold at any time. Tools and materials shall not exceed seventy-five (75) pounds in addition to the occupancy.

(5) The platform shall consist of not less than two (2) inch x ten (10) inch nominal size planks extending nor more than twelve (12) inches or less than six (6) inches beyond each end support.

(6) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail, of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends of all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(n) Bricklayers' square scaffolds.

(1) The square shall not exceed five (5) feet in width and five (5) feet in height.

(2) Members shall be not less than those specified in Table 41.

(3) The squares shall be reinforced on both sides of each corner with one (1) inch x six (6) inch gusset pieces. They shall also have diagonal braces one (1) inch x eight (8) inch on both sides running from center to center of each member, or other means to secure equivalent strength and rigidity.

(4) The squares shall be set not more than five (5) feet apart for medium duty scaffolds, and not more than eight (8) feet apart for light duty scaffolds. Bracing, one (1) inch x eight (8) inch, extending from the bottom of each square to the top of the next square, shall be provided on both front and rear sides of the scaffold.

(5) Platform planks shall be at least two (2) inch x ten (10) inch nominal size. The ends of the planks shall overlap the bearers of the squares and each plank shall be supported by not less than three (3) squares.

(6) Bricklayers' square scaffolds shall not exceed three (3) tiers in height and shall be so constructed and arranged that one (1) square shall rest directly above the other. The upper tiers shall stand on a continuous row of planks laid across the next lower tier and be nailed down or otherwise secured to prevent displacement.

(7) Scaffolds shall be level and set upon a firm foundation.

(o) Horse scaffolds.

(1) Horse scaffolds shall not be constructed or arranged more than two (2) tiers or ten (10) feet in height.

(2) The members of the horses shall be not less than those specified in Table 42.

(3) Horses shall be spaced not more than five (5) feet for medium duty and not more than eight (8) feet for light duty.

(4) When arranged in tiers, each horse shall be placed directly over the horse in the tier below.

(5) On all scaffolds arranged in tiers, the legs shall be nailed down or otherwise secured to the planks to prevent displacement or thrust and each tier shall be substantially cross braced.

(6) Horses or parts which have become weak or defective shall not be used.

(7) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail, of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed at all open sides and ends on all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section when required.

(p) Needle beam scaffold.

(1) Wood needle beams shall be not less than four (4) inch x five (5) inch in size, with the greater dimension placed in a vertical direction. Metal beams or the equivalent, conforming to paragraphs (a)(8) and (10) of this section, may be used and shall not be altered or moved horizontally while they are in use.

(2) Ropes or hangers shall be provided for supports. The span between supports on the needle beam shall not exceed ten (10) feet for four (4) inch x six (6) inch timbers. Rope supports shall be equivalent in strength to one (1) inch diameter first-grade manila rope.

(3) The ropes shall be attached to the needle beams by a scaffold hitch or a properly made eye splice. The loose end of the rope shall be tied by a bowline knot or by a round turn and a half hitch.

(4) The scaffold hitch shall be arranged so as to prevent the needle beam from rolling or becoming otherwise displaced.

(5) The platform span between the needle beams shall not exceed eight (8) feet when using two (2) inch scaffold plank. For spans greater than eight (8) feet, platforms shall be designed based on design requirements for the special span. The overhang of each end of the platform planks shall be not less than six (6) inches and not more than twelve (12) inches.

(6) When needle beam scaffolds are used, the planks shall be secured against slipping.

(7) All unattached tools, bolts, and nuts used on needle beam scaffolds shall be kept in suitable containers, properly secured.

(8) One (1) end of a needle beam scaffold may be supported by a permanent structural member conforming to paragraphs (a)(8) and (10) of this section.

(9) Each employee working on a needle beam scaffold shall be protected by a safety belt and lifeline.

(q) Plasterers', decorators', and large area scaffolds.

(1) Plasterers', lathers', and ceiling workers' inside scaffolds shall be constructed in accordance with the general requirements set forth for independent wood pole scaffolds. (See paragraph (b) and Tables 33, 34 and 39 of this section.)

(2) All platform planks shall be laid with the edges close together.

(3) When independent pole scaffold platforms are erected in sections, such sections shall be provided with connecting runways equipped with substantial guardrails.

(4) Guardrails made of lumber, not less than two (2) inch x four (4) inch (or other material providing equivalent protection), approximately forty-two (42) inches high, with a midrail of one (1) inch x six (6) inch lumber (or other material providing equivalent protection), and toeboards, shall be installed on all open sides and ends of all scaffolds more than ten (10) feet above the ground or floor. Toeboards shall be a minimum of four (4) inches in height. Wire mesh shall be installed in accordance with paragraph (a)(6) of this section.

(r) Interior hung scaffolds.

(1) An interior hung scaffold shall be hung or suspended from the roof structure or ceiling beams.

(2) The suspending wire or fiber rope shall be capable of supporting at least six (6) times the rated load. The rope shall be wrapped at least twice around the supporting members and twice around the bearers of the scaffold, with each end of the wire rope secured by at least three (3) standard wire-rope clips properly installed.

(3) For hanging wood scaffolds, the following minimum nominal size material shall be used:

(i) Supporting bearers two (2) inch x ten (10) inch on edge;

(ii) Planking two (2) inch x ten (10) inch, with maximum span seven (7) feet for heavy duty and ten (10) feet for light duty or medium duty.

(4) Steel tube and coupler members may be used for hanging scaffolds with both types of scaffold designed to sustain a uniform distributed working load up to heavy duty scaffold loads with a safety factor of four (4).

(s) Ladder jack scaffolds.

(1) All ladder jack scaffolds shall be limited to light duty and shall not exceed a height of twenty (20) feet above the floor or ground.

(2) All ladders used in connection with ladder jack scaffolds shall be heavy-duty ladders and shall be designed and constructed in accordance with American National Standards Institute A14.1-1968 Safety Code for portable wood ladders, and A14.2-1968, Safety Code for portable metal ladders. Cleated ladders shall not be used for this purpose.

(3) The ladder jack shall be so designed and constructed that it will bear on the side rails in addition to the ladder rungs, or if bearing on rungs only, the bearing area shall be at least ten (10) inches on each rung.

(4) Ladders used in conjunction with ladder jacks shall be so placed, fastened, held, or equipped with devices so as to prevent slipping.

(5) The wood platform planks shall be not less than two (2) inch nominal in thickness. Both metal and wood platform planks shall overlap the bearing surface not less than twelve (12) inches. The span between supports for wood shall not exceed eight (8) feet. Platform width shall be not less than eighteen (18) inches.

(6) Not more than two (2) employees shall occupy any given eight (8) feet of any ladder jack scaffold at any one (1) time.

(t) Window jack scaffolds.

(1) Window jack scaffolds shall be used only for the purpose of working at the window opening through which the jack is placed.

(2) Window jacks shall not be used to support planks placed between one (1) window jack and another or for other elements of scaffolding.

(3) Window jack scaffolds shall be provided with guardrails unless safety belts with lifelines are attached and provided for employee.

(4) Not more than one (1) employee shall occupy a window jack scaffold at any one (1) time.

(u) Roofing brackets.

(1) Roofing brackets shall be constructed to fit the pitch of the roof.

(2) Brackets shall be secured in place by nailing in addition to the pointed metal projections. When it is impractical to nail brackets, rope supports shall be used. When rope supports are used, they shall consist of first grade manila of at least three-quarter (3/4) inch diameter, or equivalent.

(3) A catch platform shall be installed below the working area of roofs more than sixteen (16) feet from the ground to eaves with a slope greater than four (4) inch in twelve (12) inch without a parapet. In width, the platform shall extend two (2) feet beyond the protection of the eaves and shall be provided with a guardrail, midrail, and toeboard. This provision shall not apply where employees engaged in work upon such roofs are protected by a safety belt attached to a lifeline.

(v) Crawling board or chicken ladders.

(1) Crawling board shall be not less than ten (10) inch wide and one (1) inch thick, having cleats one (1) inch x one and one-half (1 1/2) inch the Cleats shall be equal in length to the width of the board and spaced at equal intervals not to exceed twenty-four (24) inches. Nails shall be driven through and clinched on the underside. The crawling board shall extend from the ridge pole to the eaves when used in connection with roof construction, repair, or maintenance.

(2) A firmly fastened lifeline of at least three-quarter (3/4) inch diameter rope, or equivalent, shall be strung beside each crawling board for a handhold.

(3) Crawling boards shall be secured to the roof by means of adequate ridge hooks or other effective means.

(w) Form scaffolds.

(1) Form scaffolds shall be constructed of wood or other suitable materials, such as steel or aluminum members of known strength characteristics.

All scaffolds shall be designed and erected with a minimum safety factor of four (4), computed on the basis of the maximum rated load.

(2) All scaffold planking shall be a minimum of two (2) inch x ten (10) inch nominal scaffold grade, as recognized and approved grading rules for the species of lumber used, or equivalent material. Maximum permissible spans shall not exceed eight (8) feet on centers for two (2) inch x ten (10) inch nominal planking. Scaffold planks shall be either nailed or bolted to the ledgers or of such length that they overlap the ledgers at least six (6) inches. Unsupported projecting ends of scaffolding planks shall be limited to a maximum overhang of twelve (12) inches.

(3) Scaffolds shall not be loaded in excess of the working load for which they were designed.

(4) Figure-four (4) form scaffolds:

(i) Figure-four (4) scaffolds are intended for light duty and shall not be used to support loads exceeding twenty-five (25) pounds per square foot unless specifically designed for heavier loading. For minimum design criteria, see Table 43.

(ii) Figure-four (4) form scaffold frames shall be spaced not more than eight (8) feet on centers and constructed from sound lumber, as follows:

The outrigger ledger shall consist of two (2) pieces of one (1) inch x six (6) inch or heavier material nailed on opposite sides of the vertical form support. Ledgers shall project not more than three (3) feet six (6) inches from the outside of the form support and shall be substantially braced and secured to prevent tipping or turning. The knee or angle brace shall intersect the ledger at least three (3) feet from the form at an angle of approximately forty-five degrees (45), and the lower end shall be nailed to a vertical support. The platform shall consist of two (2) or more two (2) inch x ten (10) inch planks, which shall be of such length that they extend at least six (6) inches beyond ledgers at each end unless secured to the ledgers. When planks are secured to the ledgers (nailed or bolted) a wood filler strip shall be used between the ledgers. Unsupported projecting ends of planks shall be limited to an overhang of twelve (12) inches.

(5) Metal bracket form scaffolds:

(i) Metal brackets or scaffold jacks which are an integral part of the form shall be securely bolted or welded to the form. Folding type brackets shall be either bolted or secured with a locking-type pin when extended for use.

(ii) "Clip-On" or "Hook-Over" brackets may be used, provided the form walers are bolted to the form or secured by snap ties or shea-volt extending through the form and securely anchored.

(iii) Metal brackets shall be spaced not more than eight (8) feet on centers.

(iv) Scaffold planks shall be either bolted to the metal brackets or of such length that they overlap the brackets at each end by at least six (6) inches.

Unsupported projecting ends of scaffold planks shall be limited to a maximum overhang of twelve (12) inches.

(v) Metal bracket form scaffolds shall be equipped with wood guardrails, intermediate rails, toeboards, and scaffold planks meeting the minimum dimensions shown in Table 44. (Metal may be substituted for wood, providing it affords equivalent or greater design strength.)

(6) Wooden bracket form scaffolds:

(i) Wooden bracket form scaffolds shall be an integral part of the form panel. The minimum design criteria set forth herein and in Table 45 cover scaffolding intended for light duty and shall not be used to support loads exceeding twenty-five (25) pounds per square foot, unless specifically designed for heavier loading.

(ii) Scaffold planks shall be either nailed or bolted to the ledgers or of such length that they overlap the ledgers at each end by at least six (6) inches. Unsupported projecting ends of scaffold planks shall be limited to a maximum overhang of twelve (12) inches.

(iii) Guardrails and toeboards shall be installed on all open sides and ends of platforms and scaffolding over ten (10) feet above the floor or ground.

Guardrails shall be made of lumber two (2) inch x four (4) inch nominal dimension (or other material providing equivalent protection), approximately forty-two (42) inches high, supported at intervals not to exceed eight (8) feet. Guardrails shall be equipped with midrails constructed of one (1) inch x six (6) inch nominal lumber (or other material providing equivalent protection). Toeboard shall extend not less than four (4) inches above the scaffold plank.

(x) Pump jack scaffolds.

(1) Pump jack scaffolds shall:

(i) Not carry a working load exceeding five hundred (500) pounds; and

(ii) Be capable of supporting without failure at least four (4) times the maximum load.

(iii) The manufacture components shall not be loaded in excess of the manufacturer's recommended limits.

(2) Pump jack brackets, braces, and accessories shall be fabricated from metal plates and angles. Each pump jack bracket shall have two (2) positive gripping mechanisms to prevent any failure or slippage.

(3) The platform bracket shall be fully decked and the planking secured. Planking, or equivalent, shall conform with paragraph (a) of this section.

(4)

(i) When wood scaffold planks are used as platforms, poles used for pump jacks shall not be spaced more than ten (10) feet center to center. When fabricated platforms are used that fully comply with all other provisions of this paragraph (x), pole spacing may exceed ten (10) feet center to center.

(ii) Poles shall not exceed thirty (30) feet in height.

(iii) Poles shall be secured to the work wall by rigid triangular bracing, or equivalent, at the bottom, top, and other points as necessary, to provide a maximum vertical spacing of not more than ten (10) feet between braces. Each brace shall be capable of supporting a minimum of two hundred twenty-five (225) pounds tension or compression.

(iv) For the pump jack bracket to pass bracing already installed, an extra brace shall be used approximately four (4) feet above the one (1) to be passed until the original brace is reinstalled.

(5) All poles shall bear on mud sills or other adequate firm foundations.

(6) Pole lumber shall be two (2) two (2) x four's (4), of Douglas Fir, or equivalent, straight-grained, clear, free of cross-grain, shakes, large loose or dead knots, and other defects which might impair strength.

(7) When poles are constructed of two (2) continuous lengths, they shall be two (2) by fours (4), spiked together with the seam parallel to the bracket, and with ten (10)d common nails, no more than twelve (12) inches center to center, staggered uniformly from opposite outside edges.

(8) If two (2) by fours (4) are spliced to make up the pole, the splices shall be so constructed as to develop the full strength of the member.

(9) A ladder shall be provided for access to the platform during use.

(10) Not more than two (2) persons shall be permitted at one (1) time upon a pump jack scaffold between any two (2) supports.

(11) Pump jack scaffolds shall be provided with standard guardrails as defined in Section 32 of these regulations, but no guardrail is required when safety belts with lifelines are provided for employees.

(12) When a work bench is used at an approximate height of forty-two (42) inches, the top guardrail may be eliminated, if the work bench is fully decked, the planking secured, and is capable of withstanding two hundred (200) pounds pressure in any direction.

(13) Employees shall not be permitted to use a work bench as a scaffold platform.

33.3. Manually propelled mobile ladder stands and scaffolds (towers).

(a) General requirements.

(1) Application. This section is intended to prescribe rules and requirements for the design, construction, and use of mobile work platforms (including ladder stands but not including aerial ladders) and rolling (mobile) scaffolds (towers). This standard is promulgated to aid in providing for the safety of life, limb, and property, by establishing minimum standards for structural design requirements and for the use of mobile work platforms and towers.

(2) Working loads.

(i) Work platforms and scaffolds shall be capable of carrying the design load under varying circumstances depending upon the conditions of use.

Therefore, all parts and appurtenances necessary for their safe and efficient utilization must be integral parts of the design.

(ii) Specific design and construction requirements are not a part of this section because of the wide variety of materials and design possibilities. However, the design shall be such as to produce a mobile ladder stand or scaffold that will safely sustain the specified loads. The material selected shall be of sufficient strength to meet the test requirements and shall be protected against corrosion or deterioration.

(A) The design working load of ladder stands shall be calculated on the basis of one (1) or more two hundred (200)-pound persons with fifty (50) pounds of equipment each.

(B) The design load of all scaffolds shall be calculated on the basis of:

Light -- Designed and constructed to carry a working load of twenty-five (25) pounds per square foot.

Medium -- Designed and constructed to carry a working load of fifty (50) pounds per square foot.

Heavy -- Designed and constructed to carry a working load of seventy-five (75) pounds per square foot.

All ladder stands and scaffolds shall be capable of supporting at least four (4) times the design working load.

(iii) The materials used in mobile ladder stands and scaffolds shall be of standard manufacture and conform to standard specifications of strength, dimensions, and weights, and shall be selected to safely support the design working load.

(iv) Nails, bolts, or other fasteners used in the construction of ladders, scaffolds, and towers shall be of adequate size and in sufficient numbers at each connection to develop the designed strength of the unit. Nails shall be driven full length. (All nails should be immediately withdrawn from dismantled lumber.)

(v) All exposed surfaces shall be free from sharp edges, burrs or other safety hazards.

(3) Work levels.

(i) The maximum work level height shall not exceed four (4) times the minimum or least base dimensions of any mobile ladder stand or scaffold.

Where the basic mobile unit does not meet this requirement, suitable outrigger frames shall be employed to achieve this least base dimension, or provisions shall be made to guy or brace the unit against tipping.

(ii) The minimum platform width for any work level shall not be less than twenty (20) for mobile scaffolds (towers). Ladder stands shall have a minimum step width of sixteen (16) inches.

(iii) The supporting structure for the work level shall be rigidly braced, using adequate cross bracing or diagonal bracing with rigid platforms at each work level.

(iv) The steps of ladder stands shall be fabricated from slip resistant treads.

(v) The work level platform of scaffolds (towers) shall be of wood, aluminum, or plywood planking, steel or expanded metal, for the full width of the scaffold, except for necessary openings. Work platforms shall be secured in place. All planking shall be two (2) inch (nominal) scaffold grade minimum one thousand five hundred (1,500) feet (stress grade) construction grade lumber or equivalent.

(vi) All scaffold work levels ten (10) feet or higher above the ground or floor shall have a standard (four (4) inch nominal) toeboard.

(vii) All work levels ten (10) feet or higher above the ground or floor shall have a guardrail of two (2) inch x four (4) inch nominal or the equivalent installed no less than thirty-six (36) inches or more than forty-two (42) inches high, with a midrail, when required, of one (1) inch x four (4) inches nominal lumber or equivalent.

(viii) A climbing ladder or stairway shall be provided for proper access and egress, and shall be affixed or built into the scaffold and so located that its use will not have a tendency to tip the scaffold. A landing platform shall be provided at intervals not to exceed thirty (30) feet.

(4) Wheels or casters.

(i) Wheels or casters shall be properly designed for strength and dimensions to support four (4) times the design working load.

(ii) All scaffold casters shall be provided with a positive wheel and/or swivel lock to prevent movement. Ladder stands shall have at least two (2) of the four (4) casters and shall be of the seivel type.

(iii) Where leveling of the elevated work platform is required, screw jacks or other suitable means for adjusting the height shall be provided in the base section of each mobile unit.

(b) Mobile tubular welded sectional folding scaffolds.

(1) General. Units including sectional stairway and sectional ladder scaffolds shall be designed to comply with the requirements of paragraph (a) of this section.

(2) Stairway. An integral set of pivoting and hinged folding diagonal and horizontal braces and a detachable work platform shall be incorporated into the structure of each sectional folding stairway scaffold.

(3) Bracing. An integral set of pivoting and hinged folding diagonal and horizontal braces and a detachable work platform shall be incorporated into the structure of each sectional folding ladder scaffold.

(4) Sectional folding stairway scaffolds. Sectional folding stairway scaffolds shall be designed as medium duty scaffolds except for high clearance.

These special base sections shall be designed as light duty scaffolds. When upper sectional folding stairway scaffolds are used with a special high clearance base, the load capacity of the entire scaffold shall be reduced accordingly. The width of a sectional folding stairway scaffold shall not exceed four and one-half (4 1/2) feet. The maximum length of a sectional folding stairway scaffold shall not exceed six (6) feet.

(5) Sectional folding ladder scaffolds. Sectional folding ladder scaffolds shall be designed as light duty scaffolds including special base (open end) sections which are designed for high clearance. For certain special applications the six (6) foot long unit, eight (8) foot six (6) inch for an eight (8) foot unit or a ten (10) foot six (6) inch for a ten (10) foot long unit.

(6) End frames. The end frames of sectional ladder and stairway scaffolds shall be designed so the the horizontal bearers provide supports for multiple planking levels.

(7) Erection. Only the manufacturer of the scaffold or his qualified designated agent shall be permitted to erect or supervise the erection of scaffolds exceeding fifty (50) feet in height above the base, unless such structure is approved in writing by a licensed professional engineer, or erected in accordance with instructions furnished by the manufacturer.

33.4. Definitions applicable to this subpart.

(a) "Ladders"

(1) "Cleats" ladder crosspieces of rectangular cross section placed on edge on which a person may step in ascending or descending.

(2) "Single Cleat Ladder" one which consists of a pair of side rails, usually parallel, but with flared side rails permissible, connected together with cleats that are joined to the side rails at regular intervals.

(3) "Double Cleat Ladder" one that is similar to a single cleat latter, but is wider, with an additional center rail which will allow for two (2) way traffic for workmen in ascending and descending.

(b) "Scaffolding"

(1) "Bearer" a horizontal member of a scaffold upon which the platform rests and which may be supported by ledgers.

(2) "Boatswain's Chair" a seat supported by slings attached to a suspended rope, designed to accommodate one (1) workman in a sitting position.

(3) "Brace" a tie that holds one (1) scaffold member in a fixed position with respect to another member.

(4) "Bricklayers' Square Scaffold" a scaffold composed of framed wood squares which support a platform, limited to light and medium duty.

(5) "Carpenters' Bracket Scaffold" a scaffold consisting of wood or metal brackets supporting a platform.

(6) "Coupler" a device for locking together the component parts of a tubular metal scaffold. (The material used for the couplers shall be of a structural type, such as drop-forged steel, malleable iron, or structural grade aluminum.)

(7) "Crawling Board or Chicken Ladder" a plank with cleats spaced and secured at equal intervals, for use by a worker on roofs, not designed to carry any material.

(8) "Double Pole or Independent Pole Scaffold" A scaffold supported form the base by a double row of uprights, independent of support from the walls and constructed of uprights, ledgers, horizontal platform bearers, and diagonal bracing.

(9) "Float or Ship Scaffold" A scaffold hung from overhead supports by means of ropes and consisting of substantial platform having diagonal bracing underneath, resting upon and securely fastened to two (2) parallel plank bearers at right angles to the span.

(10) "Guardrail" a rail secured to uprights and erected along the exposed sides and ends of platforms.

(11) "Heavy Duty Scaffold" a scaffold designed and constructed to carry a working load not to exceed seventy-five (75) pounds per square foot.

(12) "Horse Scaffold" a scaffold for light or medium duty, composed of horses supporting a work platform.

(13) "Interior Hung Scaffold" a scaffold suspended from the ceiling or roof structure.

(14) "Ladder jack Scaffold" a light duty scaffold supported by brackets attached to ladders.

(15) "Ledgers (Stringers)" a horizontal scaffold member which extends from post to post and which supports the putlogs or bearers forming a tie between the posts.

(16) "Light Duty Scaffold" a scaffold designed and constructed to carry a working load not to exceed twenty-five (25) pounds per square foot.

(17) "Manually Propelled Mobile Scaffold" a portable rolling scaffold supported by casters.

(18) "Masons' Adjustable Multiple-Point Suspension Scaffold" A scaffold having a continuous platform supported by bearers suspended by wire rope from overhead supports, so arranged and operated as to permit the raising or lowering of the platform to desired working positions.

(19) "Maximum Rated Load" the total of all loads including the working load, the weight of the scaffold, and such other loads as may be reasonably anticipated.

(20) "Medium Duty Scaffold" a scaffold designed and constructed to carry a working load not to exceed fifty (50) pounds per square foot.

(21) "Midrail" a rail approximately midway between the guardrail and platform, secured to the uprights erected along the exposed sides and ends of platforms.

(22) "Needle Beam Scaffold" a light duty scaffold consisting of needle beams supporting a platform.

(23) "Outrigger Scaffold" a scaffold supported by outriggers or thrustouts projecting beyond the wall or face of the building or structure, the inboard ends of which are secured inside of such building or structure.

(24) "Putlog" a scaffold member upon which the platform rests.

(25) "Roofing or Bearer Bracket" a bracket used in slope roof construction, having provisions for fastening to the roof or supported by ropes fastened over the ridge and secured to some suitable object.

(26) "Runner" the lengthwise horizontal bracing or bearing members or both.

(27) "Scaffold" any temporary elevated platform and its supporting structure used for supporting workmen or materials, or both.

(28) "Single-Point Adjustable Suspension Scaffold" a manually or poweroperated unit designed for light duty use, supported by a single wire rope from an overhead support so arranged and operated as to permit the raising or lowering of platform to desired working positions.

(29) "Single-Pole Scaffold" platforms resting on putlogs or cross beams, the outside ends of which are supported on ledgers secured to a single row of posts or uprights, and the inner ends of which are supported on or in a wall.

(30) "Stone Setters' Adjustable Multiple-Point Suspension Scaffold" a swinging type scaffold having a platform supported by hangers suspended at four (4) points so as to permit the raising or lowering of the platform to the desired working position by the use of hoisting machines.

(31) "Toeboard" a barrier secured along the sides and ends of a platform to guard against the falling of material.

(32) "Tube and Coupler Scaffold" an assembly consisting of tubing which serves as posts, bearers, braces, ties, and runners, a base supporting the posts and special couplers which serve to connect the uprights and to join the various members.

(33) "Tubular Welded Frame Scaffold" a sectional panel or frame metal scaffold substantially built up of prefabricated welded sections which consists of posts and horizontal bearer with intermediate members.

(34) "Two-Point Suspension Scaffold (Swinging Scaffold)" a scaffold, the platform of which is supported by hangers (stirrups) at two (2) points, suspended from overhead supports so as to permit the raising or lowering of the platform to the desired working position by tackle or hoisting machines.

(35) "Window Jack Scaffold" a scaffold, the platform of which is supported by a bracket of jack which projects through a window opening.

(36) "Working Load" load imposed by men, materials, and equipment.

(37) "Ladder Stand" a mobile fixed size self-supporting ladder consisting of a wide flat tread ladder in the form of stairs. The assembly may include handrails.

33.5. Guardrails, handrails, and covers.

(a) General provisions. This subpart shall apply to temporary or emergency conditions where there is danger of employees or materials falling through floor, roof, or wall openings or from stairways, or runways.

(b) Guarding of floor openings and floor holes.

(1) Floor openings shall be guarded by a standard riling and toeboards or cover, as specified in paragraph (f) of this section. In general, the railing shall be provided on all exposed sides, except at entrances to stairways.

(2) Ladderway floor openings or platforms shall be guarded by standard railings with standard toeboards on all exposed sides, except at entrances to opening, with the passage through the railing either provided with a swinging gate or so offset that a person cannot walk directly into the opening.

(3) Hatchways and chute floor openings shall be guarded by one (1) of the following:

(i) Hinged covers of standard strength and construction and a standard railing with only one (1) exposed side. When the opening is not in use, the cover shall be closed or the exposed side shall be guarded at both top and intermediate positions by removable standard railings;

(ii) A removable standard railing with toeboard on not more than two (2) sides of the opening and fixed standard railings with toeboards on all other exposed sides. The removable railing shall be kept in place when the opening is not in use and should preferably be hinged or otherwise mounted so as to be conveniently replaceable.

(4) Wherever there is danger of falling through a skylight opening, it shall be guarded by a fixed standard railing on all exposed sides or a cover capable of sustaining the weight of a two hundred (200) pound person.

(5) Pits and trap-door floor openings shall be guarded by floor opening covers of standard strength and construction. While the cover is not in place, the pit or trap openings shall be protected on all exposed sides by removable standard railings.

(6) Manhole floor openings shall be guarded by standard covers which need not be hinged in place. While the cover is not in place, the manhole opening shall be protected by standard railings.

(7) Temporary floor openings shall have standard railings.

(8) Floor holes, into which persons can accidentally walk, shall be guarded by either a standard railing with standard toeboard on all exposed sides, or a floor hole cover of standard strength and construction that is secured against accidental displacement. While the cover is not in place, the floor hole shall be protected by a standard railing.

(9) Where doors or gates open directly on a stairway, a platform shall be provided, and the swing of the door shall not reduce the effective width of the platform to less than twenty (20) inches.

(c) Guarding of wall openings.

(1) Wall openings, from which there is a drop of more than four (4) feet, and the bottom of the opening is less than three (3) feet above the working surface, shall be guarded as follows:

(i) When the height and placement of the opening in relation to the working surface is such that either a standard rail or intermediate rail will effectively reduce the danger of falling, one (1) or both shall be provided;

(ii) The bottom of a wall opening, which is less than four (4) inches above the working surface, regardless of width, shall be protected by a standard toeboard or an enclosing screen either of solid construction or as specified in paragraph (f)(7)(ii) of this section.

(2) An extension platform outside a wall opening onto which materials can be hoisted for handling shall have side rails or equivalent guards of standard specifications. One (1) side of an extension platform may have removable railings in order to facilitate handling materials.

(3) When a chute is attached to an opening, the provisions of paragraph (c)(1) of this section shall apply, except that a toeboard is not required.

(d) Guarding of open-sided floors, platforms, and runways.

(1) Every open-sided floor or platform six (6) feet or more above adjacent floor or ground level shall be guarded by a standard railing, or the equivalent, as specified in paragraph (f)(1) of this section, all open sides, except where there is entrance to a ramp, stairway, or fixed ladder. The railing shall be provided with a standard toeboard wherever, beneath the open sides, persons can pass, or there is moving machinery, or there is equipment with which falling materials could create a hazard.

(2) Runways shall be guarded by a standard railing, or the equivalent as specified in paragraph (f) of this section, on all open sides, four (4) feet or more above the floor or ground level. Wherever tools, machine parts, or materials are likely to be used on the runway, a toeboard shall also be provided on each exposed side.

(3) Runways used exclusively for special purposes may have the railing on one (1) side omitted where operating condition necessitate such omission, providing the falling hazard is minimized by using a runway not less then eighteen (18) inches wide.

(4) Where employees entering upon runways become thereby exposed to machinery, electrical equipment, or other danger not a falling hazard, additional guarding shall be provided.

(5) Regardless of height, opensided floors, walkways, platforms, or runways above or adjacent to dangerous equipment, pickling or galvanizing tanks, degreasing units, and similar hazards shall be guarded with a standard railing and toeboard.

Stairway railings and guards.

(1) Every flight of stairs having four (4) or more risers shall be equipped with standard stair railings or standard handrails as specified below, the width of the stair to be measured clear of all obstructions except handrails:

(i) On stairways less than forty-four (44) inches wide having both sides enclosed, at least one (1) handrail, preferably on the right side descending;

(ii) On stairways less than forty-four (44) inches wide having one (1) side open, at least one (1) stair railing on the open side;

(iii) On stairways less than forty-four (44) inches wide having both sides open, one (1) stair railing on each side;

(iv) On stairways more than forty-four (44) inches wide but less than eighty-eight (88) inches wide, one (1) handrail on each enclosed side, and one (1) intermediate stair railing located approximately midway of the width;

(v) On stairways eighty-eight (88) or more inches wide, one (1) handrail on each enclosed side, one (1) stair railing on each open side, and one (1) intermediate stair railing located approximately midway of the width.

(2) Winding stairs shall be equipped with a handrail offset to prevent walking on all portions of the treads having width less than six (6) inches.

(f) Standard specifications.

(1) A standard railing shall consist of top rail, intermediate rail, toeboard and posts, and shall have a vertical height of approximately forty-two (42) inches from upper surface of top rail to floor, platform, runway, or ramp level. The top rail shall be smooth-surfaced throughout the length of the railing. The intermediate rail shall be halfway between the top rail in the floor, platform, runway, or ramp. The ends of the rails shall not overhang the terminal posts except where such overhang does not constitute a projection hazard. Minimum requirements for standard railings under various types of construction are specified in the following paragraphs:

(i) For wood railings, the posts shall be of at least two (2) inch x four (4) inch stock spaced not to exceed eight (8) feet; the top rail shall be of at least two (2) inch x four (4) inch stock; the intermediate rail shall be of at least one (1) inch x six (6) inch stock.

(ii) For pipe steel railings, post and top and intermediate railings shall be at least one and one-half (1 1/2) inches nominal diameter with posts spaced not more than eight (8) feet on centers.

(iii) For structural steel railings, posts and top and intermediate rails shall be of two (2) inch x two (2) inch by three-eights (3/8)inch angles or other metal shapes of equivalent bending strength, with posts spaced not more than eight (8) feet on centers.

(iv) The anchoring of posts and framing of members for railings of all types shall be of such construction that the completed structure shall be capable of withstanding a load of at least two hundred (200) pounds applied in any direction at any point on the top rail, with a minimum of deflection.

(v) Railings receiving heavy stresses from employees trucking or handling materials shall be provided additional strength by the use of heavier stock, closer spacing of posts, bracing, or by other means.

(vi) Other types, sizes, and arrangements of railing construction are acceptable, provided they meet the following conditions:

(a) A smooth-surfaced top rail at a height above the floor, platform, runway, or ramp level of approximately fortytwo (42) inches;

(b) A strength to withstand at least the minimum requirement of two hundred (200) pounds top rail pressure with a minimum of deflection;

(c) Protection between top rail and floor, platform, runway, ramp, or stair treads, equivalent at least to that afforded by a standard intermediate rail;

(d) Elimination of overhang of rail ends unless such overhang does not constitute a hazard.

(2) A stair railing shall be of construction similar to a standard railing, but the vertical height shall be not more than thirty-four (34) inches nor less than thirty (30) inches from upper surface of top rail to surface of tread in line with face of riser at forward edge of tread.

(3)

(i) A standard toeboard shall be four (4) inches minimum in vertical height from its top edge to the level of the floor, platform, runway, or ramp. It shall be securely fastened in place and have not more than one-quarter (1/4) inch clearance above the floor level. It may be made of any substantial material, either solid, or with openings not over one (1) inch in greatest dimension.

(ii) Where material is piled to such height that a standard toeboard does not provide protection, paneling or screening from floor to intermediate rail or to top rail shall be provided.

(4)

(i) A standard handrail shall be of construction similar to a standard railing except that it is mounted on a wall or partition, and does not include an intermediate rail. It shall have a smooth surface along the top and both sides of the handrail. The handrail shall have an adequate handhold for any one (1) grasping it to avoid falling. Ends of the handrail shall be constructed so as not to constitute a projection hazard.

(ii) The height of handrails shall be not more than thirty-four (34) inches nor less than thirty (30) inches from upper surface of handrail to surface of tread, in line with face of riser or to surface of ramp.

(iii) All handrails and railing shall be provided with a clearance of approximately three (3) inches between the handrail or railing and any other object.

(5) Floor opening covers shall be of any material that meets the following strength requirements:

(i) Conduits, trenches, and manhole covers and their supports, when located in roadways, and vehicular aisles, shall be designed to carry a truck rear-axle load of at least two (2) times the maximum intended load.

(ii) The floor opening cover shall be capable of supporting the maximum intended load and so installed as to prevent accidental displacement.

(6) Skylight openings that create a falling hazard shall be guarded with a standard railing, or covered in accordance with paragraph (5)(ii) of this paragraph.

(7) Wall opening protection shall meet the following requirements:

(i) Barriers shall be of such construction and mounting that, when in place at the opening, the barrier is capable of withstanding a load of at least two hundred (200) pounds applied in any direction (except upward), with a minimum of deflection at any point on the top rail or corresponding member.

(ii) Screens shall be of such construction and mounting that they are capable of withstanding a load of at least two hundred (200) pounds applied horizontally at any point on the near side of the screen. They may be of solid construction, of grill work with openings not more than four (4) inch wide with length unrestricted.

33.6. Guarding floor and wall openings and holes.

(a) Wall hole. An opening less than thirty (30) inches but more than one (1) inch high, of unrestricted width, in any wall or partition; such as a ventilation hole or drainage scuper.

(b) Where there is a hazard of materials falling through a wall hole and the lower edge of the near side of the hole is less than four (4) inches above the floor, and the far side of the hole more than five (5) feet above the next lower level, the hole shall be protected by a standard toeboard, or an enclosing screen either of solid construction or as specified in this section.

33.7. Stairways.

(a) On all structures, two (2) or more floors (twenty (20) feet or over) in height, stairways, ladders, or ramps shall be provided for employees during the construction period.

(b) Stairway railings and guardrails shall meet the requirements of Section 33.5., paragraphs (e) and (f) of these regulations.

(c) All parts of stairways shall be free of hazardous projections, such as protruding nails.

(d) Debris, and other loose materials, shall not be allowed on or under stairways.

(e) Slippery conditions on stairways shall be eliminated as soon as possible after they occur.

(f) Permanent steel or other metal stairways, and landings with hollow pan-type treads that are to be filled with concrete or other materials, when used during construction, shall be filled to the level of the nosing with solid material. The requirement shall not apply during the period of actual construction of the stairways themselves.

(g) Wooden treads for temporary service shall be full width.

(h) Metal landings shall be secured in place before filling.

(i) Temporary stairs shall have a landing not less than thirty (30) inches in the direction of travel at every twelve (12) feet of vertical rise.

(j) Stairs shall be installed at angles to the horizontal between thirty (30) degrees and fifty (50) degrees.

(k) Rise height and tread width shall be uniform throughout any flight of stairs including any foundation structure used as one (1) or more treads of the stairs.

(l) All stairs shall be lighted in accordance with this section.

(m) Spiral stairways shall not be permitted except for special limited usage and secondary access situations where it is not practical to provide a conventional stairway.

33.8. Definitions applicable to this subject.

(a) "Floor Hole" an opening measuring less than twelve (12) inches but more than one (1) inch in its least dimension in any floor, roof, or platform through which materials but not persons may fall, such as belt hold, pipe opening, or slot opening.

(b) "Floor Opening" an opening measuring twelve (12) inches or more in its least dimension in any floor, roof, or platform through which persons may fall.

(c) "Handrail" a bar or pipe supported on brackets from a wall or partition, as on a stariway or ramp, to furnish persons with a handhold in case of tripping.

(d) "Nose, Nosing" that portion of a tread projecting beyond the face of the riser immediately below.

(e) "Platform" a working space for persons, elevated above the surrounding floor or ground, such as a balcony or platform for the operation of machinery and equipment.

(f) "Runway" a passageway for persons, elevated above the surrounding floor or ground level, such as a footwalk along shafting or a walkway between buildings.

(g) "Rise" the vertical distance from the top of a tread to the top of the next higher tread.

(h) "Stair Platform" an extended step or landing breaking a continuous run of stairs.

(i) "Stair Railing" a vertical barrier erected along exposed sides of a stariway to prevent falls of persons.

(j) "Stairs, Stairways" a series of steps leading from one (1) level or floor to another, or leading to platforms, pits, boiler rooms, crossovers, or around machinery, tanks, and other equipment that are used more or less continuously or routinely by employees or only occasionally by specific individuals. For the purpose of this subpart, a series of steps and landings having three (3) or more rises constitutes stairs or stairway.

(k) "Standard Railing" a vertical barrier erected along exposed edges of a floor opening, wall opening, ramp, platform, or runway to prevent falls of persons.

(l) "Standard Strength and Construction" any construction of railings, covers, or other guards that meets the requirements of this subpart.

(m) "Toeboard" a vertical barrier at floor level erected along exposed edges of a floor opening, platform, runway, or ramp to prevent falls of materials.

(n) "Tread Width" the horizontal distance from front to back of tread, including nosing, when used.

(o) "Wall Opening" an opening at least thirty (30) inches high and eighteen (18) inches wide, in any wall or partition, through which persons may fall, such as a yardarm doorway or chute opening.

W. Va. Code R. § 36-23-33