The addition of your outriggers adds 4 feet to the width and effectively creates a new length for each model. Our analysis shows the base geometry changes on all three models. 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. 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. * including vertical posts, guardrails, casters, etc. The table below shows at what height OSHA's restraint provision (§1926.451(c)(1)) would require the indicated scaffold model, when used without outriggers, to be restrained (by guying, tying, bracing, or equivalent means) to prevent tipping.
Use of the scaffolds when no one is on them while they are moved We will refer to them respectively as the 4-foot, 6-foot and 7-foot models. 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.
Your materials describe three "lock-pin" scaffold models. However, in light of the width measurements in your materials, we have calculated the maximum permissible scaffold height for use without restraints. īased on the information you provided, we were unable to calculate the scaffold's total height.
ROLLING TOWER SCAFFOLD RENTAL FREE
a free standing scaffold shall be considered safe when the total height is equal to or less than four times the minimum or least base dimension. OSHA continues to use the relationship between total height and least base dimension to calculate height-to-base width ratio. 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. (1) Supported scaffolds with a height to base width ( including outrigger supports, if used) ratio of more than four to one shall be restrained from tipping by guying, tying, bracing, or equivalent means. Section 1926.451(c)(1) states: Criteria for supported scaffolds. 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. 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. Question: Do the designs that I have submitted regarding "lock-pin" mobile scaffolds meet applicable OSHA construction requirements for height-to-base width ratios for supported scaffolds? 1įirst, please note that OSHA neither approves nor endorses products. I apologize for the delay in our completing this letter. Your inquiry concerns the adequacy of outrigger designs for your "lock-pin" mobile scaffolds used in construction. This is in response to your December 30, 2002, letter to the Occupational Safety and Health Administration (OSHA), as well as several conversations with members of my staff. Re: Whether a mobile scaffold outrigger design meets the requirements of.
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