The strength of the platform is critical, obviously, to the occupant. Frankly, if the platform cannot hold the anticipated load, you won’t like the result. The strength of the platform is determined by the designer and must be based on the anticipated load – that’s why the designer must know what the scaffold is going to be used for prior to designing the scaffold and the platform. Criteria that determines the strength of the platform include the type of material (is it wood, wood veneer, metal or plastic?), the dimensions of that material, the orientation of those dimensions, and the span of the platform member between supports. For example, a 2×10 wood member used on edge, the 10 inches vertical, holds much more than a 2×10 on the flat, the 10 inches horizontal. (Of course, a 2×10 on edge is really tough to walk on unless you’re really good at balancing!)
The construction of the platform is critical to the success of the platform. Not only is the platform required to remain in place but it must not make hazards for the user. For example, if the platform isn’t wide enough, there are gaps in the platform where a foot or body can fall through, or the bearing isn’t sufficient, can make the scaffold experience unpleasant, if not hazardous, for the user. The scaffold industry has established minimum expectations for platforms and these expectations have been codified in the OSHA standards.
A scaffold platform is really only a platform if it is safe. Whenever a fall hazard exists a platform must have a guardrail system unless the platform users are utilizing personal fall protection equipment. Each platform must also have a safe form of access. Finally, all platforms must have falling object protection whenever that hazard exists.
Here are a few guidelines for the design, construction, and safe use of a platform:
- If solid sawn wood plank are used, make sure they have a 4 to 1 safety factor. Solid sawn plank used in General Industry applications must be scaffold grade;
- Follow manufacturer’s load guidelines for laminated veneer lumber (lvl) and other fabricated plank, making sure not to exceed load limits;
- Make sure all plank and platforms are in good shape and not detrimentally damaged (see SIA guidelines and manufacturers’ recommendations for planks and other products);
- Make sure all platforms comply with the construction requirements of federal OSHA and other requirements:
- Minimum Overhang: 6” minimum unless secured from movement
- Maximum Overhang: 12” for short plank, 18” for plank longer than 10’ (federal) or secured from movement
- Minimum Overlap: 12” or secured from movement
- Maximum gap between units: 1”
- Maximum space between back of platform and guardrail system: 9-1/2”
- Maximum space between front of platform and work surface: 14” (16” CA)
- If using solid sawn plank, make sure it is from a legitimate supplier with a legitimate grade stamp and documentation;
- Provide proper access to all platforms;
- Inspect platforms before use to make sure there is proper bearing and fall protection;
- Verify plank and platform strength before placing any loads on the platform;
- All scaffolds have a load limit. Make sure you do not overload the scaffold with the number of platforms and the load on each platform. You supplier can help with that determination. If you are the supplier and do not have that answer, you need to get it;
- If plywood and joists are used to make the platform, make sure the plywood is secured from movement and both the plywood and joists have been sized by a qualified person for the anticipated load;
- Don’t paint wood plank-you can’t see the defects;
- Make sure the platform scaffold components are compatible with each other. For example, if joists and plywood are used, make sure the guardrail system is at the correct height. If wood plank are used and overhanG the supports, make sure that access is not blocked;
- On suspended scaffolds, make sure the stirrups and other components are compatible with the platform;
- When using modular platforms, make sure the proper connections are used and secured;
- Do not overload the platform or the scaffold!
There are other factors to consider when choosing a platform and a qualified scaffold designer will know the advantages of each. If you are a user, know the limitations and load capacities of the platform before using it. Remember, if the plank breaks, there’s nothing to stop you but the ground and that may be a long way down. You falling 6 feet results in a force of about 2,400 pounds. The wood plank that is supposed to stop you can only hold 1,000 pounds. How many planks do you think you’ll break (and have to pay for) before you stop?