We see a lot of structural mezzanines in our business in a range of facilities. They range from professionally manufactured to home-made, with quite a few fabricated by a local shop. It’s a good business for the fabrication shops (although maybe not so much for end-users, given the pitfalls), and if you go that route, you need to be sure your mezzanine fabricator is complying with OSHA & local safety regulations, particularly on guard railing, stairs and gates. You also have to look at local building codes. If your fabricator doesn’t routinely work with mezzanines, this is something you’ll have to do on your own. It’s not something to dismiss lightly. Honestly the best policy is to look at established vendors like WilDeck if you don’t want to micro-manage the details of building permits, code compliance, and OSHA’s blessings.
Companies have been forced to extensively rework mezzanines when they don’t handle these issues on the front end. If you do go that route, the first place to look for noncompliance is in the guard rail. OSHA regulations are pretty straightforward:
“Top edge height of top rails, or equivalent guardrail system members, shall be 42 inches (1.1 m) plus or minus 3 inches (8 cm) above the walking/working level. When conditions warrant, the height of the top edge may exceed the 45-inch height, provided the guardrail system meets all other criteria of this paragraph (§ 1926.502(b)).”
Simple enough on the height issues. Make sure the plans are detailed on that regard, and make sure the final product meets it.
Midrails, screens, mesh, intermediate vertical members, or equivalent intermediate structural members shall be installed between the top edge of the guardrail system and the walking/working surface when there is no wall or parapet wall at least 21 inches (53 cm) high.
In many cases, the midrails are for seismic areas. They are more expensive — about $1,100 more for a mezzanine approximately 30 x 30 – but often worth it, even if code doesn’t specify a midrail. And while a thousand dollars isn’t cheap, it might end up that way because it makes it more difficult for things to slip between the upper & lower rail.
Then we address capacity:
Guardrail systems shall be capable of withstanding, without failure, a force of at least 200 pounds (890 N) applied within 2 inches (5.1 cm) of the top edge, in any outward or downward direction, at any point along the top edge.
When the 200 pound (890 N) test load specified in paragraph (b)(3) of this section (§ 1926.502) is applied in a downward direction, the top edge of the guardrail shall not deflect to a height less than 39 inches (1.0 m) above the walking/working level. Guardrail system components selected and constructed in accordance with the appendix B to subpart M of this part will be deemed to meet this requirement.
It goes on to say that midrails or mesh screen need to withstand 150 pounds of force applied in any downward or outward direction at any point along the mid-rail. It’s also got notes on how to finish the rail so that it won’t lacerate or cut people. It shouldn’t snag on clothing. (In other words, a well-finished rail should be smooth to the touch at any points, have all the burrs ground down, and the sharp edges blunted.)
There is a lot more there. I would recommend an experienced mezzanine vendor, but if you do go the fabrication shop route and they aren’t experienced builders, be aware of the safety rules and how they apply to you. Check with the OSHA site, get your building permits (in some areas, a mezzanine of certain size can be considered a “second floor” and that opens up an entire new can of worms) You also need to be sure be sure that you’re meeting IBC rules and cover all of your bases.
Scott Stone is a 23-year veteran of the material handling industry.