437-004-0370 Scaffolding (1) Scope. This section has safety requirements for scaffolds. (2) Definitions. Scaffolding terms mean: (a) Bearer. A horizontal part of a scaffold on which the platform rests and which may use ledgers as support. (b) Boatswain’s chair. A seat supported by slings attached to a suspended rope, designed to accommodate one worker in a sitting position. (c) Brace. A tie that holds one scaffold part in a fixed position with respect to another. (d) Crawling board or chicken ladder. A plank with cleats spaced and secured at equal intervals, for use on roofs, not designed to carry any material. (e) Double pole or independent pole scaffold. A scaffold supported from 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. (f) Guardrail. A rail secured to uprights that run along the exposed sides and ends of platforms. (g) Heavy duty scaffold. A scaffold built to carry a working load of not more than 75 pounds per square foot. (h) Horse scaffold. A scaffold for light or medium duty, made of horses supporting a work platform. (i) Ladder jack scaffold. A light duty scaffold supported by brackets attached to ladders. (j) Ledger (stringer). A horizontal scaffold member that extends from post to post and supports the putlogs or bearer forming a tie between the posts. (k) Light duty scaffold. A scaffold built to carry a working load not more than 25 pounds per square foot. (l) Manually propelled mobile scaffold. A portable rolling scaffold mounted on casters. (m) Maximum intended load. The total of all loads including the working load, the weight of the scaffold, and such other loads as may be reasonably anticipated. (n) Medium duty scaffold. A scaffold built to carry a working load not more than 50 pounds per square foot. (o) Mid-rail. A rail approximately midway between the guardrail and platform and secured to the uprights along the exposed sides and ends of platforms. (p) Putlog. A scaffold part on which the platform rests. (q) Roofing bracket. A bracket used in sloped roof construction. It has a way for fastening to the roof or is supported by ropes fastened over the ridge and secured to some suitable object. (r) Runner. The lengthwise horizontal bracing or bearing parts or both. (s) Scaffold. Any temporary elevated platform and its supporting structure used for supporting workers or materials or both. (t) Single pole scaffold. Platforms resting on putlogs or crossbeams, the outside ends of which are on ledgers secured to a single row of posts or uprights and the inner ends of which are on or in a wall. (u) Toeboard. A barrier secured along the sides and ends of a platform, to keep material from falling. (v) Tubular welded frame scaffold. A sectional, panel, or frame metal scaffold made of prefabricated welded sections, that has posts and bearers with intermediate connecting members, braced with diagonal or cross braces. (w) Working load. Load imposed by workers, material and equipment. (3) General requirements for all scaffolds. (a) The footing or anchorage for scaffolds must be sound, rigid, and able to carry the maximum intended load without settling or displacement. Do not use unstable objects such as barrels, boxes, loose brick, or concrete blocks to support scaffolds or planks. (b) Scaffolds and their components must be able to support at least four times the maximum intended load. (c) Scaffolds and other devices mentioned here must be in safe condition. Do not alter or move an occupied stationary scaffold. (d) Remove from use any damaged or weakened scaffold until repairs are done. (e) Do not overload scaffolds. Follow manufacturers’ instructions. (f) Loaded planks or platforms must not deflect more than 1/60th of the span (2 inches in 10 feet). (g) Nails or bolts used to make scaffolds must be strong enough and in sufficient numbers at each connection to assure the designed strength of the scaffold. Do not subject nails to a straight pull. Drive all nails completely. (h) Overlap all planking or platforms (minimum 12 inches) or secure them from movement. (i) There must be a ladder or equivalent safe access. (j) Scaffold planks must extend over their end supports not less than 6 inches nor more than 18 inches. (k) The poles, legs, or uprights of scaffolds must be plumb, and securely and rigidly braced to prevent swaying and displacement. (l) Use a tag line when hoisting materials onto a scaffold. (m) There must be overhead protection for employees exposed to overhead hazards. (n) If persons work or pass under the scaffolds there must be a screen between the toeboard and the guardrail, along the entire opening. The screen must be No. 18 gauge U.S. Standard Wire 1/2-inch mesh or the equivalent. (o) Employees must not work on scaffolds during storms or high winds. (p) Employees must not work on scaffolds covered with ice or snow or that have slippery surfaces. (q) Accumulations of tools, materials, and debris must not cause a hazard. (r) Wire or fiber rope for scaffold suspension must be able to support at least six times the intended load. (s) Do not use shore scaffolds or lean-to scaffolds. (t) Lumber sizes, used here, refer to nominal sizes except where otherwise stated. (u) Use anchor bolts, reveal bolts, or other equivalent means to secure scaffolds to permanent structures. Do not use window cleaners’ anchor bolts. (v) Take special precautions to protect scaffold members, including any wire or fiber ropes, when using a heat-producing process. (4) General requirements for wood pole scaffolds. (a) Scaffold poles must be plumb and on a foundation that prevents settling. (b) Where wood poles are spliced, the ends must be square and the upper section must rest squarely on the lower section. There must be wood splice plates, at least 4 feet long, on at least two adjacent sides and overlapping the abutted ends equally. These plates must be the same width as the pole. Splice plates of other materials of equivalent strength are acceptable. (c) Set independent pole scaffolds as near to the wall of the building as practicable. (d) Guy or tie pole scaffolds to the building or structure. If they are more than 25 feet high or long, secure them at intervals not more than 25 feet vertically and horizontally. (e) Set putlogs or bearers with their greater dimensions vertical, long enough to project over the ledgers of the inner and outer rows of poles at least 3 inches for proper support. (f) Reinforce every wooden putlog on single pole scaffolds with a 3/16 x 2-inch steel strip or equivalent secured to its lower edge throughout its length. (g) Ledgers must be long enough to extend over two pole spaces. Do not splice ledgers between the poles. Reinforce ledgers with bearing blocks securely nailed to the side of the pole to form a support for the ledger. (h) Use diagonal bracing to prevent the poles from moving in a direction parallel with the wall of the building, or from buckling. (i) Use cross bracing between the inner and outer sets of poles in independent pole scaffolds. Cross brace the free ends of pole scaffolds. (j) There must be full diagonal face bracing across the entire face of pole scaffolds in both directions. Splice the braces at the poles. (k) Lay platform planks with their edges close together so the platform will be tight with no spaces through which tools or material can fall. (l) When lapped, each plank must lap its end supports at least 12 inches. Where the ends of planks abut each other to form a flush floor, the butt joint must be at the centerline of a pole. Rest abutted ends on separate bearers. Use intermediate beams where necessary to prevent dislodgment of planks due to deflection. Nail or cleat the ends to prevent their dislodgment. (m) When a scaffold turns a corner, lay the platform planks to prevent tipping. The planks that meet the corner putlog at an angle must be laid first, extending over the diagonally placed putlog far enough to have a safe bearing, but not far enough to involve any danger from tipping. The planking running in the opposite direction at right angles must be laid to extend over and rest on the first layer of planking. (n) When moving platforms to the next level, leave the old platform undisturbed until the new putlogs or bearers are in place. (o) Install guardrails, 2 x 4 inches or the equivalent, between 36 inches and 42 inches high at all open sides on all scaffolds more than 10 feet above the ground or floor. The mid-rail, when required, must be 1 x 4-inch lumber or equivalent, and there must be toeboards at least 4 inches high. Use wire mesh according to paragraph OAR 437-004-0370(3)(o). (p) All wood pole scaffolds 60 feet or less in height must be built according to tables 1 through 6. If they are more than 60 feet high, a registered professional engineer must design them. A copy of the typical drawings and specifications must be available to the employer and for inspection purposes. [Tables not included. See ED. NOTE.] (5) Tubular welded frame scaffolds. (a) Metal tubular frame scaffolds, including accessories such as braces, brackets, trusses, screw legs, ladders, etc., must be able to safely support four times the maximum intended load. (b) Spacing of panels or frames must be consistent with the loads imposed. (c) Scaffolds must have cross bracing or diagonal braces, or both, to secure vertical members together laterally. The cross braces must be long enough to automatically square and aline vertical members so that the erected scaffold is always plumb, square, and rigid. All brace connections must be secure. (d) Scaffold legs must be on adjustable bases or plain bases on mud sills or other foundations adequate to support the maximum intended load. (e) The frames must be one on top of the other with coupling or stacking pins to provide proper vertical alinement of the legs. (f) Where uplift may occur, lock panels together vertically with pins or other equivalent means. (g) Install guardrails, 2 x 4 inches or the equivalent, between 36 inches and 42 inches high at all open sides on all scaffolds more than 10 feet above the ground or floor. The mid-rail, when required, must be 1 x 4-inch lumber or equivalent, and there must be toeboards at least 4 inches high. Use wire mesh according to paragraph OAR 437-004-0370(3)(o). (h) All tubular metal scaffolds must be able to support four times the maximum intended loads. (i) To prevent movement, secure the scaffold to the building or structure at intervals not more than 30 feet horizontally and 26 feet vertically. (j) Maximum permissible spans of planking must conform with paragraph OAR 437-004-0370(3)(g). (k) A registered professional engineer must design drawings and specifications for frame scaffolds more than 125 feet high above the base plates. Copies must be available to the employer and for inspection purposes. (l) Only competent and experienced personnel may set up tubular welded frame scaffolds. (m) Frames and accessories for scaffolds must be in good repair. Remove them from use until they have no defects, unsafe conditions and are in compliance with this section. Do not use any broken, bent, excessively rusted, altered, or otherwise structurally damaged frames or accessories. (n) Make periodic inspections of all welded frames and accessories. Complete any maintenance, including painting, or minor corrections recommended by the manufacturer, before further use. (6) Boatswain’s chairs. (a) The chair seat must be not less than 12 by 24 inches, and 1-inch thick. Use a seat with reinforcement on the underside to prevent the board from splitting. (b) The two fiber rope seat slings must be 5/8-inch diameter, reeved through the four seat holes to cross each other on the underside of the seat. (c) Seat slings must be at least 3/8-inch wire rope when a worker is using a heat producing process such as gas or arc welding. (d) Protect the worker with a safety life belt and lifeline attached to substantial members of the structure (not the scaffold), or to securely rigged lines, that will safely suspend the worker in case of a fall. (e) The tackle must have the correct size ball bearing or bushed blocks and properly spliced 5/8-inch diameter first-grade manila. (f) The roof irons, hooks, or the object to which the tackle is anchored must be secure. Tiebacks, when used, must be at right angles to the face of the building and securely fastened to a chimney. (7) Horse scaffolds. (a) Horse scaffolds must not be more than two tiers or 10 feet high. (b) The members of the horses must be not less than those in Table 7. [Table not included. See ED. NOTE.] (c) Space horses not more than 5 feet for medium duty and not more than 8 feet for light duty. (d) When arranged in tiers, each horse must be directly over the horse in the tier below. (e) On all scaffolds arranged in tiers, nail the legs to the planks to prevent displacement or thrust and cross brace each tier. (f) Do not use horses or parts that are weak or defective. (g) Install guardrails, 2 x 4 inches or the equivalent, between 36 inches and 42 inches high at all open sides on all scaffolds more than 10 feet above the ground or floor. The midrail, when required, must be 1 x 4-inch lumber or equivalent, and there must be toeboards at least 4 inches high. Use wire mesh according to paragraph OAR 437-004-0370(3)(o). (8) Ladder-jack scaffolds. (a) All ladder-jack scaffolds are only for light duty and may not be more than 20 feet above the floor or ground. (b) All ladders used with ladder-jack scaffolds must be heavy-duty and designed and constructed according to 437-004-0340. (c) The ladder jack must bear on the side rails in addition to the ladder rungs, or if bearing on rungs only, the bearing area must be at least 10 inches on each rung. (d) To prevent slipping, use special devices, secure placement or anchor ladders used with ladder jacks. (e) The wood platform planks must be not less than 2 inches (nominal) thick. Both metal and wood platform planks must overlap the bearing surface not less than 12 inches. The span between supports for wood must be not more than 8 feet. The platform must be at least 18 inches wide. (f) Not more than two persons may be on any given 8 feet of a ladder-jack scaffold at one time. (9) Roofing brackets. (a) Roofing brackets must fit the pitch of the roof. (b) Nail brackets in place in addition to using the pointed metal projections. Drive the nails all the way into the roof. When using rope supports, they must be first-grade manila of at least 3/4-inch diameter, or equivalent. (c) A substantial catch platform must be below the working area of roofs more than 20 feet from the ground to eaves with a slope more than 3 inches in 12 inches and no parapet. In width the platform must extend 2 feet beyond the projection of the eaves and have a safety rail, midrail, and toeboard. This does not apply where employees are using a personal fall protection system. (10) Crawling boards or chicken ladders. (a) Crawling boards must be not less than 10 inches wide and 1 inch thick, with 1 x 1-1/2 inch cleats. The cleats must be equal in length to the width of the board and spaced at equal intervals not more than 24 inches. Drive nails through and clinch them on the underside. The crawling board must extend from the ridge pole to the eaves when used with roof construction, repair, or maintenance. (b) A firmly fastened lifeline of at least 3/4-inch rope must be strung beside each crawling board for a handhold. (c) Use adequate ridge hooks or equivalent effective means to secure crawling boards to the roof. (11) Manually propelled mobile scaffolds. (a) The height of free-standing mobile scaffold towers must not be more than four times the smallest base dimension. (b) Casters must be able to support four times the maximum intended load. All casters must have a positive locking device. (c) Scaffolds must have cross bracing and horizontal bracing. (d) Platforms must have tight planking for the full width of the scaffold except for necessary entrance opening. Platforms must not be free to move. (e) There must be a fixed or built-in ladder or stairway for access and exit. (f) Move the mobile scaffold by force applied near or as close to the base as practicable. Keep the scaffold stable during movement. Move scaffolds only on level floors with no obstructions or openings. (g) Workers may not ride on manually propelled scaffolds unless the following conditions exist: (A) The floor or surface is within 3 degrees of level, and free from pits, holes, or obstructions; (B) The smallest dimension of the scaffold base is at least one-half of the height. If it has outriggers, they must be on both sides of the staging; (C) The wheels have rubber or similar resilient tires. (h) Scaffolds must rest upon a suitable footing and be plumb. Lock the casters or wheels to prevent unintended movement. (i) Guardrails made of lumber, not less than 2 X 4 inches (or other material providing equivalent protection), between 39 and 42 inches high, with a midrail and toeboards, must be on all open sides and ends of scaffolds more than 10 feet above the ground or floor. Toeboards must be at least 4 inches high. If people may pass under the scaffold, use wire mesh between the toeboard and top of the guardrail. [ED. NOTE: Tables referenced are available from the agency.] Statutory/Other Authority: ORS 654.025(2) & 656.726(3) Statutes/Other Implemented: ORS 654.001 - 654.295 History: OSHA 4-1998, f. 8-28-98, cert. ef. 10-1-98