Mezzanines: The Space Race

Mezzanines have always been a good option for facilities feeling the space crunch. The cost and disruption associated with construction make moving, building or expanding a facility unappealing, and many find a better alternative by looking up. Before they get to that point, however, modern facility managers should exhaust all avenues of waste reduction. Adding square footage to house more resources than you need defeats the purpose of efficient growth. In line with lean thinking, the mezzanine should be designed to exacting specifications that account for every detail of its planned and potential uses.

“The conversation used to be much more casual,” says Scott Dachel, outside regional sales manager for Wildeck. “Instead of just giving us a layout, saying, ‘yeah, there will be some conveyor up there, but don’t worry about it,’ and asking for a quote, we work much more hand-in-hand with partners and integrators to ask and answer a lot more questions.”

In the past year, Dachel says those detailed conversations have resulted in mezzanines that are less a mere platform and more an integrated piece of equipment. Fittingly, a mezzanine is depreciable equipment and subject to different calculations of return on investment than a building addition. As such, its interactions with other machinery, people and processes can be optimized.

“What type of conveyor will be up there?” Dachel asks. “How fast? How many legs? What types of product will it carry? Will heavy bins, vats or tanks on the mezzanine be supported by legs or a skid frame that spreads the load? What deflection criteria should we factor into the platform to allow for the inertia of a high-speed sorter? Is it a tilt tray or sliding shoe, since each sorter transfers different stresses to the structure? What cut-outs are needed for incline conveyor to pass through the structure?”

Once the current goals are considered, you can make allowances for future plans. Might more equipment or storage be added in coming years? Do you expect to add a mezzanine extension, an access stairway or some sort of lift in the future? Might you want to disassemble the mezzanine and take it to a different location?

“Some who never asked these questions beefed up their mezzanine unnecessarily and spent more money than they needed,” Dachel says. “If we have great information about what’s going up there, we can save the customer money.”

Safety boosters

There are plenty of examples of mezzanines installed or modified without due consideration of applicable standards and codes. According to Javier Ramirez, field manager for East Coast Storage Equipment and a 27-year veteran of the mezzanine design and installation world, that scenario is much rarer.

“Lately we’re noticing customers are more concerned with meeting codes and regulations brought on by a recent wave of enhanced enforcement,” Ramirez says. “Years ago, people just did what they wanted, but they are now more involved in the proper engineering processes.”

It’s one thing to comply with municipal definitions of what constitutes a second floor, but most projects are defined by safety concerns. In addition to including safeguards on all new mezzanines, many existing ones are a target for increased security measures. Legacy safety gates are typically swing- or slide-style gates, which depend on workers to routinely secure them. Dachel says OSHA now prefers gates that are closed on one side at all times, like overhead or pivot-style gates. Where there is not sufficient space to install such a system, older gates—though grandfathered—might be augmented with alert systems that display lights and sounds when open.

The movement of goods between levels is also fraught with potential risks. Vertical reciprocating conveyors (VRC) have become a popular alternative to features like chutes.

“When the product or a tote hits the bottom of a chute, it can damage product or injure someone nearby,” Dachel says. “Even worse is the operator leaning to put something on the chute. We’ve heard of some folks falling down the chute.”

A lift with controlled descent eliminates splash at the bottom, and an automated infeed requires no stretching or shoving from the operator. VRCs for pallet drops are not designed for human passengers, but many workers use legacy systems to avoid trips up and down the stairs.

“There have been big safety advancements for pallet drop systems,” says Matthew Myers, director of business development for REB Storage Systems. “New VRCs feature interlocks so the door has to be closed to operate, and the controls are several feet away from the door itself so you can’t start it while inside.”

For new and old lifts alike, Myers notes the increased use of barriers around the entire system to prevent workers’ hands from getting caught in moving parts or from inadvertently walking underneath a lift.
Aside from worker safety, recent regulations have also increased the focus on food safety. In recent years, mezzanine suppliers have added new designs, coatings and features to eliminate catch points for fluid and bacterial buildup. According to Shannon Salchert, marketing manager for Cubic Designs, systems for the food and beverage industry have become a big area of growth.

A launchpad for growth

Speaking of growth, the e-commerce boom is also playing into the strengths of mezzanines for new building design. Salchert says mezzanines were not traditionally top of mind for new buildings and were seen more as a way to expand space in existing facilities.

“I recently attended a conference where a lot of people were looking at new construction and wanted to implement a mezzanine,” she says. “We’re hearing more than the usual number talking about new building in general. In addition to the depreciation benefit of a mezzanine, customers don’t have to build as big as they thought. One customer significantly shrank the size of their initial proposal by going two stories high.”

She also notes a number of e-fulfillment centers and integrators now prefer a wide-flange design, which excels at very large spans and offers a shallower profile of about 6 inches, as opposed to bar joist systems that run around 2 feet thick. The goal is to maximize headroom underneath, and REB’s Myers emphasizes that good mezzanine design should also consider what is below.

“One customer recently built an extremely large mezzanine hung entirely from the roof,” says Myers, who explains that the roof structure had accounted for the mezzanine load in advance, but REB had to work very closely with the architect to account for sway loads.

“It definitely cost more than a floor-supported structure, but the mezzanine was located above the shipping operation, where it was important for the customer to maintain a free and clear environment,” Myers says. “They had the foresight to realize it was better to have flexibility with the shipping layout than have columns in the way. For a building with a 30-year life, it is best to plan for change.”

Others are specifying mezzanines for near-perfect consistency. For years, Myers says, the standard allowance for deflection—the degree to which a mezzanine’s platform sways—was the length between support members divided by 180, or about 3/4 of an inch over a 10-foot span. Mezzanine-based systems sensitive to vibration, like some conveyor-mounted scanners, might call for L/360. In one case, Myers said a customer with an in-motion scale avoided the cost of the more rigid specification by building an independent support for the unit down through the mezzanine to the floor.

As automation becomes increasingly common in warehouses and distribution centers, some have already embraced the future by designing mezzanines for people-free, lights-out automated operations.

“We’re seeing a trend with automation where robotic picking is located upstairs, and it’s conveyed down to pick, pack and ship,” Salchert says. “It’s been interesting lately to see how people are using mezzanines differently.”