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Understanding engineered tents

Features, Management | April 1, 2011 | By:

What tent installers need to know about the growing demand for engineered tents.

Event planners and the general public appreciate the beauty and functionality of tents, but these days, tent rental companies and code officials are more likely to look for something else when evaluating a tent: engineering paperwork.

“You could design a tent that is adequately strong, but without the engineering stamp, it will have no value as far as complying to codes,” says Spencer Etzel, president of the SEC Group of Wilsonville, Ore. “What engineered tents give you is a structure system that somebody has looked through very closely and determined it has the proper strength.”

Economy Tent Intl., based in Miami, Fla., can attest to the increase in demand for engineered tents. President Hal Lapping says the company fields two to three times as many requests for engineering data than it did a few years ago. But does engineering documentation always translate into a safe tent? Or is there more that tent installers—and code officials—need to understand about engineered tents?

“You can have the best engineered tent in the world, but it needs to have proper and adequate staking, and that has to be done on-site,” Lapping says.

Code crackdown

Janice Grieshop, owner of Celina, Ohio-based Celina Tent Inc., agrees that the permitting process has expanded beyond fire retardance certificates. Code officials are looking closely at engineering documentation and wind loads as a result of tent collapses that have killed or injured people.

“Those are the incidents people look at and think, ‘Boy, are tents safe?’ They’re safe, but they’re only as safe as the people who put them up,” she says. “The biggest thing is when you get a tent engineered, it’s engineered under certain conditions. So if you are in Ohio and you set it up in clay, when you go to Florida, you are putting it up in sand. That alters everything. If you have a rental company that doesn’t have stake bars, it’s really not engineered anymore, because one component of the engineering is missing.”

The International Building Code sets forth requirements for tents in excess of 400 square feet. But every jurisdiction develops its own rules, Etzel says. “Typically, we see it come into play at 2,000 or 3,000 square feet,” he says.

According to Etzel, the tenting landscape is changing, as evidenced by his experience in working in Arizona and California. “Last year, there was a large breakdown in Scottsdale, and now permitting there and in Phoenix is stricter,” he says. “In Los Angeles County, they put out a new [wind-load] regulation for 100 mph instead of 85 mph, so that upped the wind speed you have to design to.”

Wayne Rendely, a consulting engineer in Huntington Station, N.Y., posits that one of the reasons municipalities are demanding more engineering certificates is that temporary structures are growing. “As tents get larger and larger, they’re becoming buildings,” he says.

Weighing the needs

Tent manufacturers and renters generally agree that nonengineered tents suffice for backyard birthday parties and barbecues, but tents for events open to the general public should be engineered.

The size of a tent, importance of the event, number of people that will be inside the structure and duration of the installation all factor into the requirements, says Jeff McInnes, North American sales manager for HTS-USA/Höcker Structures of Jupiter, Fla. “On top of that, you have your local building codes and how they’re being managed by city inspectors,” he says.

McInnes notes that many code officials are not well versed in comprehending the engineering of temporary buildings.

porary buildings. “Many of our tents are engineered to meet permanent building codes,” he says. “Some communities will forego having a temporary code and request you meet their permanent codes.”

Dennis Birdsall, general manager of TentLogix, a Stuart, Fla.-based tent rental company, knows the frustration of working with code officials who lack familiarity with tent systems.

“Everything they have learned is about solid-structure buildings,” he says. “They question the calculations done by engineers certifying tents. I think they misunderstand the power of a stake in the ground.”

In those situations, a responsive manufacturer is a tent installer’s best friend. A tent renter shouldn’t hesitate to ask the manufacturer for engineering details, Birdsall says.

“At the same time, understand your building department and work with them,” he says. “Get that information, whether it be five or 15 items. … Go to them two months, six weeks, four weeks ahead of time. The earliest you can get them to feel comfortable, the better they will understand it and give you the permit.”

Working in harmony

Tent renters must bear in mind that geography and topography affect engineering needs. Rendely offers this example: Three tents, all rated to withstand 50 mph winds, are installed in three distinct locations: one in a forest of 50-foot trees, another in an open field with no trees and the third by a large body of water. “You can imagine, of these three different tents, that one would be more likely to see a big wind than another,” Rendely says.

Code officials in locations with high snow loads and strong winds are likely to be more aware of the demands upon the structure, McInnes says.

“You need to know the maximum wind load the tent is designed for and the resulting reactions so that the anchoring can be properly done,” McInnes says. “That information is usually provided by the tent manufacturer.”

While wind and snow loads put pressure on tent exteriors, pressure also can come from within, Birdsall says.

“From a rigging, harnessing and decor perspective, you may come in and say, ‘Okay, I have 13,000 pounds of truss to hang for my lighting.’ … You may have a pole tent engineered for 90 mph winds, but what you are not going to get out of a pole tent is the ability to hang 13,000 pounds of trussing,” he says.

An engineered tent provides components that all work together and are designed to handle loads as they are transferred through the system, Lapping says. In contrast, on a nonengineered tent, one part may be stronger than others and have a higher load capacity.

“It creates a scenario of ‘the weakest link will break first,’ he says. “That could result in the use of parts that are not consistently engineered to work in harmony with every other part.”

The precise measurements that give engineered tents strength also provide uniformity that affects appearance. If the frame is off even a couple of millimeters from one section to another, the fabric that covers it billows and wrinkles, McInnes adds.

When and why a tent rental company adds engineered tents to its inventory will vary based on climate and geographical conditions, local code enforcement and the kind of events a company works on. Tent renters who understand engineered tents, are aware of the specific installation challenges of their locality and know how to work successfully with local code officials will get the most out of their investment.

Janice Kleinschmidt is a freelance writer based in Palm Springs, Calif.

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