We will be responding in a series of separate letters in response; this is the first in that series. Supported Scaffolds. Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guying, tying, bracing, or an equivalent means. Re: Tie-in requirements for supported scaffolds; §:1926.451(c)(1)(ii); errors in Non-Mandatory Appendix E. 3. Your materials describe three "lock-pin" scaffold models. The platform height of a rolling scaffold must not exceed four (4) times the smallest base dimension (Cal/OSHA and some Government agencies require a stricter ratio of 3 to 1) Always keep casters locked while on scaffold. First fastening device should be attached at the closed horizontal member to the 41 height. For example, a scaffolding structure with a base width of 3 meters can have a height of up to 12 meters; We apologize for the misunderstanding and resulting delay in providing this response. However, our calculations in the tables were based on using outriggers on both sides. Since scaffold stability is assessed based on the least dimension and since the nominal length in this scenario becomes the least dimension, maximum unrestrained heights must not exceed four times the nominal length. Also, from time to time we update our guidance in response to new information. An aspect ratio is the relationship between width and height of images. Height to base width ratio. 21-4 Construction Health and Safety Manual SCAFFOLDS 2. A tie is always required when the base of the scaffold exceeds a height to width ratio of 4:1 (California and some local regulations require a 3:1 ratio). How can one prevent supported scaffolding from tipping? Your inquiry concerns the adequacy of outrigger designs for your "lock-pin" mobile scaffolds used in construction. When that criteria is applied to a narrow scaffold (scaffolds with a height to base width ratio of more than 4:1) — for example, a supported scaffold that is 2 feet wide and 40 feet high — the employer would be required to tie, guy, or brace the scaffold at approximately the 8-foot level and then not again until every 20-foot increment. The captions appear to conflict with the language in §:1926.451(c)(1)(ii) that provides for first tie installation "at the closest horizontal member to the 4:1 height." With prescribed post spacing the scaffold height in this case can be up to 125 feet. A qualified person must design the tie-ins. If (as one example) the user were to add 2-foot outriggers at each corner and perpendicular to the long side of the scaffold base section, the base width dimension would increase to such an extent that it becomes greater than the nominal length. The height to base ratio for a supported scaffold must be 4:1 (state plans may vary). 1926.451(c)(1) How can one prevent supported … Supported scaffolds with a height to base width (including outrigger supports, if used) ratio of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing, or equivalent means as follows: By its terms, §:1926.451(c)(1)(ii), at levels above the initial tie-in and below the top tie-in, establishes. (1) You must make sure supported scaffolds with a height to least base di-mension ratio of greater than four to one are prevented from tipping by one or more of the following: (a) Guying; (b) Tying; (c) Bracing; (d) Other equivalent means. This is required when a height to base width ratio is greater than 4:1. vertical ties repeat every 26 feet or less for scaffolds that are greater than 3 feet in width; and scaffolds with a height-to-base ratio of greater than 4:1 are restrained from tipping by guying, tying or bracing. Sincerely, Height to smallest base dimension — Supported scaffolds with a height-to-smallest-base-width ratio of more ... every 26 feet if the scaffold is greater than 3 feet wide. Many of these requirements relate to the manner in which the scaffold is used and the loads imposed on them. However, where appropriate, we try to give some guidance to employers to help them assess whether products are appropriate to use and provide OSHA-required protection. The width is always the first number. The supports that give supported scaffolds their name need to feature base plates, mud sills … Guys, ties, and braces must be installed according to the scaffold manufacturer’s recommendations or at the closest horizontal member to the 4:1 height and be repeated vertically at locations of horizontal membe… Section 1926.452(w)(6) prohibits movement of mobile scaffolds with employees riding on them unless certain requirements are met. If the ratio is not maintained, ties or guys must be used. Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guy-ing, tying, bracing, or an equivalent means. Each plank must not extend over its support more than 12 inches; 18 inches if platform is greater than 10 feet. • Horizontally—at each end; at intervals not to Supported scaffolds' poles, legs, posts, frames, and uprights must bear on base plates and mud sills, or other adequate firm foundation. Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guying, tying, bracing, or an equivalent means. A supported scaffold with a height-to-base ratio (including outriggers supports, if used) of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing or equivalent means as follows: . Alternatively, guardrail systems, canopies, or catch platforms may be installed to retain materials. vertical ties repeat every 26 feet or less for scaffolds that are greater than 3 feet in width; and scaffolds with a height-to-base ratio of greater than 4:1 are restrained from tipping by guying, tying or bracing. WAC 296-874-40004 Prevent supported scaffolds from tipping. [ back to text ], Occupational Safety & Health Administration. • Any scaffold with a height-to-base width ratio of 4-to-1 or greater should be restrained from tipping by means of outriggers, guying, tying or bracing. How can one prevent supported scaffolding from tipping? Working Out Height Capacity of Scaffolding. All scaffold frames and uprights should use base plates, and … Or, it could be 1920 x 1080, 1280 x 720, or any other width/height combinations that can be calculated to equal 16:9. If they in fact have not been so designed, the heights listed in the tables above would have to be lowered to meet the 2:1 ratio for use of the scaffolds when they are moved with workers on them. Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guy-ing, tying, bracing, or an equivalent means. Not using outriggers As the Agency stated in a 1983 letter2. A commenter had suggested that the standard requires tie-in at the closest point above the 4:1 height. Do the captions in the Non-mandatory Appendix override the requirement in §:1926.451(c)(1)(ii)? I. . Some common 1:1 ratios are an 8 x 8 inch photo, a 1080 x 1080 pixel image, or typically any profile picture template on social media sites (think Facebook). Are supported scaffolds with a height to base width ratio of more than 4 to 1 restrained from tipping by guying, tying, bracing, or equivalents? 15. Figure 21-3: Castor-Type Rolling Scaffold Gate Banana clip Castor wheel with brake and swivel lock Brake Horizontal Bracing. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. As an example, a ratio of 16:9 could be 1600 pixels in width by 900 pixels in height. If you need additional information, please contact us by fax (202-693-1689) at: U.S. Department of Labor, OSHA, Office of Construction Standards and Guidance. However, in light of the width measurements in your materials, we have calculated the maximum permissible scaffold height for use without restraints. missing parts due to area obstructions). Occupational Safety and Health Administration, Severe Storm and Flood Recovery Assistance. Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guying, tying, bracing, or … Russell B. Swanson, Director David A. Beauchamp, President All scaffolds with a height to base ratio of more than four to one must be secured to the structure or guyed to prevent the scaffold from tipping over. Prevention of supported scaffolding platform from tipping . How can one prevent supported scaffolding from tipping? These are great for containing items and tools on the scaffold. a free standing scaffold shall be considered safe when the. 1816 River Bend Road Miles, Director -- Directorate of Field Operations, to Mr. Budd. Russell B. Swanson, Director Supported scaffolds with a height to base width ratio of more than 4:1 must be restrained by guying, tying, bracing, or an equivalent means. Selecting the least dimension provides the following widths: 4-foot scaffold is 4 ft.; 6-foot scaffold is 6 ft.; 7-foot scaffold is 7 feet. Re: Whether a mobile scaffold outrigger design meets the requirements of 29 CFR 1926.451(c)(1). When scaffold planks are abutted, each abutted end is required to rest on a separate support surface. The general height of light duty aluminium mobile scaffold must not exceed three times the minimum base dimension e.g. [ back to text ], Occupational Safety & Health Administration, In 1983, OSHA explained that, for the purposes of the scaffold height-to-base width ratio, the Agency uses the "total height" in relationship to the smaller base dimension. • The scaffold components, if produced by different manufacturers or with dissimilar materials, should fit together without force, while maintaining the structural integrity of the scaffold. (1) Supported scaffolds with a height to base width (including outrigger supports, if used) ratio of more than four to one (4:1) shall be restrained from tipping by guying, tying, bracing, or equivalent means, as follows: OSHA requirements are set by statute, standards and regulations. OSHA continues to use the relationship between total height and least base dimension to calculate height-to-base width ratio. Figure 21-4: Farm Wagon-Type Rolling Scaffold OSHA does not agree with the SIA suggestion that guys, ties, and braces be installed at the closest horizontal member. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov. For a scaffold with a narrow base width of less than 1.2 m, the height of Based on the information you provided, we were unable to calculate the scaffold's total height. Guys, ties, and braces shall be installed every 20 ft. vertically and 30 ft. horizontal to prevent scaffold from tipping. The materials you submitted do not indicate that you have designed and constructed the "lock-pin" scaffolds to meet or exceed "nationally recognized stability test requirements." Supported scaffolds may reach four times the base width before restraints are required. Guys, ties, and braces must be installed at locations where horizontal members support both inner and outer legs 2. Outrigger frames, when used, [must be] installed. We attempted to resolve that with you, but we were unable to obtain a response; consequently, our office closed the file. Please consult the OSHA standard 29 CFR 1926.451 for these types of scaffold situations. Scaffolds with a height to base width ratio of more than 3:1 must be restrained from tipping over by guying, tying, or bracing. I apologize for the delay in our completing this letter. You have submitted nine letters to the Occupational Safety and Health Administration (OSHA) containing a number of questions on the construction scaffold standard (29 CFR Part 1926 Subpart L).1 We will be responding in a series of separate letters in response; this is the first in that series. This letter constitutes OSHA's interpretation of the requirements discussed. OSHA's decision to reject that suggestion was explained in the Preamble's discussion of §:1926.451(c)(1)(ii) in Volume 61 of the Federal Register at page 46042: We appreciate your pointing out that the captions in the Non-mandatory Appendix are in error. Question: QUESTION 14 Scaffolds And Components Must Be Inspected By A Before Each Workday And After Any Incident That Could Weaken Them. . Question 1(b): Non-mandatory Appendix E to Subpart L purports to contain two illustrations of the maximum vertical tie spacing on supported scaffolds as required by §:1926.451(c)(1)(ii). base dimensions than 5.4m. All scaffold frames and uprights should use base plates, and mud sills are required if it is set on dirt. Guys, ties, and braces — Guys, ties, and braces must be installed where horizontal members support both inner and outer legs. • Any scaffold with a height-to-base width ratio of 4-to-1 or greater should be restrained from tipping by means of outriggers, guying, tying or bracing. 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