How Much Weight Can A Scaffold Hold?

By David H. Glabe, P.E. / September 1, 2005

How much?  No, not money, but how much can the scaffold hold?  Have you ever wondered about that?  If you have, that is not good for the simple and straightforward fact that if you are involved with the rental, sale, erection or use of scaffolds you are required to know the answer.  That’s right; it’s in the federal OSHA standards.  Look it up!  Go to the training requirements and if you are a scaffold user, find 29 CFR 1926.454(a)(4) which succinctly states:  (users shall be trained in) “the maximum intended load and the load-carrying capacities of the scaffold used.”  If you erect, inspect and/or provide scaffolds for others, find 29 CFR 1926.454(b)(3) which requires you to know: “the design criteria, maximum intended load-carrying capacity and intended use of the scaffold.”

What is the intent of these standards?  These standards are there to ensure that people like you and I use the scaffold in a safe manner, in a manner where we will never put more weight on the scaffold than it can safely hold.  The standards are rather explicit in this regard.  In fact, all parties involved with the scaffold have an obligation here.  The designer must know what the scaffold is going to be used for and how much it is to support.  The erector must know how it will be used so it can be built to accommodate the anticipated loads.  The daily inspector of the scaffold must know not only how much the scaffold can support but also how much  load is actually on the scaffold.  And finally, the scaffold user must know the limits of the scaffold so he/she does not put any more workers or materials on the scaffold than it can safely support.

There are two types of loads.  The first is the allowable load and the second is the actual load.  The allowable load is determined by the manufacturer and as the name implies, is the load that you are permitted, or allowed, to place on the scaffold.  On the other hand, the actual load is the load that you are going to actually put on the scaffold.  For all scaffolds, the actual load must never be more than the allowable load.  If the actual load is more than the allowable load it will be in violation of the OSHA standards and will collapse the scaffold at the worst condition.

Let’s look at the allowable load first.  Where does it come from?  It comes from the manufacturer of the scaffold.  Responsible manufacturers will use the standardized test procedures developed by the Scaffold, Shoring and Forming Institute (SSFI).  The manufacturer will test the scaffold to determine how much weight it can support at the time it collapses.  Using the data from the tests, a safety factor will be applied to the test results and the allowable load is calculated.  This is the load that the scaffold can be expected to support, provided the scaffold is erected according to the manufacturer’s guidelines and recommendations.  This obviously includes the use of undamaged components, proper bracing and proper foundations.  The allowable load will vary, based on the manufacturer, the type of scaffold (is it a frame scaffold, suspended scaffold or systems scaffold?), the material, and other factors.  For example, a scaffold frame that is 3 feet high will hold more than one 5 feet high, assuming all other things are equal.  Because of these variations, “one size doesn’t fit all.”  Just because a scaffold frame from manufacturer A looks like the frame from manufacturer B doesn’t mean that it will carry the same load.  You need to obtain the allowable load data from your manufacturer.

The second type of load, the actual load does not come from the manufacturer; it comes from you.  If you are the user of the scaffold, it is your obligation to make sure you do not overload the scaffold.  The actual load is comprised of three specific loads; the scaffold equipment load, the platform load, and the live load.  The scaffold equipment load is the actual weight of the scaffolding equipment.  This includes the vertical members, the horizontal members, the bracing, and any other components that are part of the scaffold structure.  The platform load is the weight of the components used for the platform.  This would be the plank or other materials that are used to construct the platform.  The live load includes the workers, tools and materials that will be supported by the scaffold.  The combination of these three loads makes up the actual load and can never be more than the allowable load.

What does all this mean?  This means that all involved parties must discuss the use of the scaffold and the anticipated live load the scaffold must support.  This also means that the user of the scaffold must control the amount of material and the number of workers that will be on the scaffold.  Remember, the higher the scaffold, the less live load and plank levels it will support.  Also, remember that a scaffold can be designed to support any actual load.  It is up to the user to inform the designer of the requirements.

Tags: 29 CFR 1926.454 actual scaffold load allowable scaffold load forming OSHA Standards & Regulations OSHA training requirements Resources Safety Hazards scaffold Shoring and Forming Institute test procedures

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