Is it plank or a platform that you stand on? Is this a tough question? Why is a concept so easy in theory so difficult in application? The simple answer to the first question is that scaffold plank can be used to construct a platform. For a variety of reasons, it gets complicated, or so it seems.
The Federal Occupational Safety and Health Administration, OSHA, describes a scaffold platform as a “work surface elevated above lower levels. Platforms can be constructed using individual wood planks, fabricated planks, fabricated decks, and fabricated platforms.” In an attempt to include the largest variety of products that can be used to construct a platform, OSHA refers to the various components as “platform units.” While the experienced scaffolder will recognize that wood plank can be platform units, those not so knowledgeable will easily become confused since “platform unit” is not defined in the OSHA standards other than to say: “Each platform unit (e.g. scaffold plank, fabricated plank, fabricated deck, or fabricated platform)” as a way of defining a platform unit. The intent of the platform standards is to ensure a safe work surface for the scaffold user. This means that the worker should expect a surface that has sufficient strength, doesn’t deflect too much, doesn’t have any big holes to fall through, and is relatively flat.
Having stated these expectations, where does that leave us when it comes to the specifics? It depends on what you are using for “platform units.” It also depends on the applicable scaffold standards. Is it General Industry or Construction? Let’s take a look at some of the things it takes to have a decent scaffold platform:
- All platform units shall have a safety factor of four. This means that if you are going to put 250 pounds on the platform unit, it has to hold at least 1,000 pounds before it breaks.
- If you have a 2×10 plank, it has to be 4 times stronger than the load it will hold.
- If you are using a platform unit as described above, in other words a 2×10 wood plank, a fabricated plank such as a laminated veneer lumber 2×10, or a fabricated deck (read that to be a hook plank) the space between units cannot be more than 1 inch.
- If you are using solid sawn lumber for a platform unit, that is a plank cut out of a tree, it must be scaffold grade if OSHA General Industry standards apply, and it must have a 4 to 1 safety factor if OSHA Construction Industry standards apply. (In Construction Industry applications, it does not have to be scaffold grade but the Scaffold Industry Association recommends that only scaffold grade solid sawn plank be used.)
- You can use Styrofoam as a platform unit but you better make sure you have that 4 to 1 safety factor!
- If you are using laminated veneer lumber, or other platform units fabricated from wood, again it has to have that 4 to 1 safety factor.
- The minimum width of a scaffold platform, for most supported scaffolds, is 18 inches. You can get by with less if you can show that you don’t have room to construct an 18 inch platform.
- Platforms are to be “fully decked” between the front uprights and the guardrail system. Great idea where a guardrail is being used. I have no idea what that means when there is no guardrail. Some people think that means the full width of the scaffold. Suppose you have a nine foot wide (not long but wide) bay; does this mean the platform should be nine feet wide?
- Platforms constructed with plank and plywood are legal, and safe too, notwithstanding an incorrect OSHA Letter of Interpretation that claimed one couldn’t inspect the plank if it was covered by plywood.
- OSHA has a plank span chart in non-mandatory Appendix A of the Construction Scaffold standards. You can follow this chart if you want. Just make sure the plank you are using equals the strength used for the chart. Of course, if your plank is stronger than what the chart is based on, then you can’t use the chart. Get a qualified person to tell you what your plank can do.
- Make sure you know what you are buying when it comes to plank. Unscrupulous purveyors of scaffold plank have a tendency to overstate their products capability. (If the deal sounds too good to be true, it probably is.)
- If you choose to construct your platform with joists, such as aluminum beams, and plywood, make sure it is designed to support the intended load. In other words, have a qualified person design it.
- It is assumed that if platform units hang over their supports at least 6 inches they won’t fall off. If you think your platform units may fall off, secure them so they don’t.
- Don’t let your platform units hang over their supports too far as this will result in a diving board (also called a widow maker). This is not good. Unless you secure the opposite end, don’t let your platform units stick out more than 12 inches for platform units 10 feet or less in length or 18 inches for longer plank.
- Overlap your platform units at least 12 inches unless you secure them.
Well, these are a few things to think about when you are installing or working on platform units. Consult the OSHA, ANSI and SIA standards and codes for additional important information. Remember this: there is no back-up for a failed platform unit like there is for other scaffold components. In engineering jargon, the platform has no redundancy. If the platform unit you are standing on breaks you are history. Some people suggest that the platform below will stop you. Unfortunately, by the time you hit the deck below you will have built up enough energy to break that one too. By the time you hit the ground you will have broken a lot of plank that you will have to pay for as soon as you get out of the hospital! Don’t take chances on damaged product, misrepresented product, faulty product, or poorly placed product. That’s what the standards say, in spite of the use of the term “platform unit.”