Use of the scaffolds when an employee is on them while they are moved It is usually expressed as two numbers, such as 3:2, 4:3 or 16:9. [ back to text ], Occupational Safety & Health Administration. It is subject to the 3-to-1 height-to-width ratio and is impractical for heights greater than 7.5 m (25 ft). The width is always the first number. This letter constitutes OSHA's interpretation of the requirements discussed. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov. Working Out Height Capacity of Scaffolding. Are supported scaffolds with a height to base width ratio of more than four to one (4:1) restrained from tipping by guying, tying, bracing, or equivalents? Occupational Safety and Health Administration, Severe Storm and Flood Recovery Assistance. However, in light of the width measurements in your materials, we have calculated the maximum permissible scaffold height for use without restraints. This limits the height of platforms with standard outrigger stabilizers and single span towers to approximately 9 m (30 ft). Mobile (Rolling) Scaffold Height must not exceed four times the .  Height to smallest base dimension—Supported scaffolds with a height -to smallest base width ratio of more than 4-to-1 (including outrigger supports) must be restrained from tipping by ties, guys, braces, or equivalent means. 1926.451(c)(1) … Note that our enforcement guidance may be affected by changes to OSHA rules. After your communications with my staff on January 13, 2005, we understand now that you are requesting a response to each question. We will be making a technical correction to the Non-mandatory Appendix so that it reflects the language in §:1926.451(c)(1)(ii). April 8, 2005 This letter constitutes OSHA's interpretation of the requirements discussed. Medium duty scaffolds – permitting up to 240kg / squrem; Heavy or Specialized duty scaffolds – permitting up to 240kg / squrem . Either the manufacturers’ recommendation or the following placements must be used for guys, ties, and braces: • Horizontally—at each end; at intervals not to 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… We have paraphrased your questions regarding tying-in scaffolds as follows: With prescribed post spacing the scaffold height in this case can be up to 125 feet. The general height of light duty aluminium mobile scaffold must not exceed three times the minimum base dimension e.g. The aspect ratio of molded feature height versus feature width for scaffolds was as high as 5:1 (150-μm strut height; 30-μm strut width), which exceeded previous reports for replica-molded PGS scaffolds in which the feature height-versus-width ratios were 2:1 or lower. Using outriggers David A. Beauchamp, President In addition, the variable working conditions at jobsites and possible alterations or misapplications of an otherwise safe product could easily create a hazardous condition beyond the control of the manufacturer. Please consult the OSHA standard 29 CFR 1926.451 for these types of scaffold situations. [Emphasis added.] A platform greater than 10 feet in length shall not extend over its support more than 18 inches, unless it is designed and installed so that the cantilevered portion of the platform is able to support employees without tipping, or has guardrails which block employee access to the cantilevered end; Page 4 3.4.1.10. However, in light of the width measurements in your materials, we have calculated the maximum permissible scaffold height for use without restraints. An aspect ratio is the relationship between width and height of images. − The height to base width ratio of the scaffold during movement is greater than 2 to 1, unless the scaffold is designed and constructed to meet or exceed nationally recognized stability test requirements (such as ANSI/SIA A92.5 and A92.6) (1926.452(w)(6)(ii)) Retraining Also, from time to time we update our guidance in response to new information. The ties should be repeated every 30 feet horizontally and vertically at 20 feet for scaffolds 3 feet wide or less, or 26 feet for scaffolds wider than 3 feet. Supported scaffolds with a height to base width ratio of more than 41 must be restrained from tipping by guying, tying, or bracing. I. Use of the scaffolds when no one is on them while they are moved 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." The width is always the first number. Working Out Height Capacity of Scaffolding The load capacity of scaffolding is determined by a height to base ratio of 4:1, Meaning the scaffold can be up to four times the minimal base width. Also, from time to time we update our guidance in response to new information. 1926.451(c)(2)(i) and (ii) Restraining. 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. [29 CFR 1926.451(c)(1)]Note: Install guys, ties, and braces at locations where horizontal members support both inner and outer legs. First fastening device should be attached at the closed horizontal member to the 41 height. 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. Supported Scaffolds (cont. This aspect ratio is commonly used for print photographs, mobile screens, and social media platforms, but it’s not ideal for most TV or digital formats. I believe that this criteria is insufficient and allows for an unsafe condition. (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: 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). We attempted to resolve that with you, but we were unable to obtain a response; consequently, our office closed the file. When scaffold planks are abutted, each abutted end is required to rest on a separate support surface. 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. • 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. After your communications with my staff on January 13, 2005, we understand now that you are requesting a response to each question. 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. Temecula, CA 92591 Miles, Director -- Directorate of Field Operations, to Mr. Budd. Base plates Be sure to use vertical and horizontal tie-ins to keep the scaffold from falling into, or away from, a structure. Guys, ties, or braces must be installed where horizontal members support inner and outer legs when the scaffold has a height/width ratio greater than: a.2 to 1 b.3 to 1 c.4 to 1 d.5 to 1. c. The space between adjacent planks and the space between the plank and the uprights must be no more than: a.1/2 inch b.1 inch c.1 1/2 inches d.2 inches. We will be making a technical correction to the Non-mandatory Appendix so that it reflects the language in §:1926.451(c)(1)(ii). Height to base width ratio for mobile scaffolds with/without outriggers. As the Agency stated in a 1983 letter, . Russell B. Swanson, Director Supported Scaffolds. )Footings must support loaded scaffoldScaffold uprights mustbe plumb and braced toprevent swayingInstall guys, ties, andbraces to prevent tippingSupported scaffolds witha height-to-base widthratio greater than 4:1must be tied to thestructureBusiness & Legal Reports, Inc. When a supported scaffold reaches a height that is more than four times its minimum base dimension (4:1), it will be restrained by guys, ties, or braces to prevent it from tipping. Section 1926.451(c)(1) states: 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. This is required when a height to base width ratio is greater than 4:1. Figure 21-4: Farm Wagon-Type Rolling Scaffold The supports that give supported scaffolds their name need to feature base plates, mud sills … I apologize for the delay in our completing this letter. Height to smallest base dimension — Supported scaffolds with a height -to smallest base width ratio of more than 4-to-1 (including outrigger supports) must be restrained from tipping by ties, guys, braces, or equivalent means. In each of those illustrations, there are identical captions that read, "First tie closest frame header or bearer above 4 times the minimum base dimension." Guys, ties, and braces must be installed according to the scaffold manufacturers recommendations or at the closest horizontal member to the 4:1 Height ratio and be repeated every 20 vertical feet for narrow scaffolds (3ft or less in width), and Every 26 vertical feet for scaffold greater than 3 feet in width Supported scaffolds with a height to base width (including outrigger supports, if used) ratio of more than four to one (4:1) four to one (4:1) First, please note that OSHA neither approves nor endorses products. Mobile scaffolds must meet a stricter height to base width ratio if workers remain on the scaffold during movement. 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. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov. Supported scaffolds with a height to base width ratio of more than 41 must be restrained from tipping by guying, tying, or bracing. 1816 River Bend Road They are nominally 4 feet long by 26 inches wide, 6 feet long by 29 inches wide, and 7 feet long by 40 inches wide. How can one prevent supported scaffolding from tipping? Answer WAC 296-874-40004 Prevent supported scaffolds from tipping. Footings must support. Every 20 feet after for scaffolds less than 3 feet wide, 26 feet for ones wider than 3 feet. Supported scaffolds' poles, legs, posts, frames, and uprights must bear on base plates and mud sills, or other adequate firm foundation. A 1:1 ratio means that an image’s width and height are equal, creating a square. • Horizontally—at each end; at intervals not to Our analysis shows the base geometry changes on all three models. Figure 21-3: Castor-Type Rolling Scaffold Gate Banana clip Castor wheel with brake and swivel lock Brake Horizontal Bracing. The addition of your outriggers adds 4 feet to the width and effectively creates a new length for each model. We apologize for the misunderstanding and resulting delay in providing this response. Your inquiry concerns the adequacy of outrigger designs for your "lock-pin" mobile scaffolds used in construction. As an example, a ratio of 16:9 could be 1600 pixels in width by 900 pixels in height. To prevent them from tipping over, OSHA specified the maximum height of supported scaffolds before they have to be restrained. How can one prevent supported scaffolding from tipping? Or, it could be 1920 x 1080, 1280 x 720, or any other width/height combinations that can be calculated to equal 16:9. Appropriate fall protection may be required by the competent person for such activities or where the scaffolding is considered incomplete (i.e. It is usually expressed as two numbers, such as 3:2, 4:3 or 16:9. Dear Mr. Beauchamp: Question: QUESTION 14 Scaffolds And Components Must Be Inspected By A Before Each Workday And After Any Incident That Could Weaken Them. Many of these requirements relate to the manner in which the scaffold is used and the loads imposed on them. 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