Doorway Dilemma

March 28, 2009 07:52 AM

Build it wide and high and it still might end up being too small. When designing doors to get modern farm equipment in and out of machine sheds or farm shops, it pays to think big.
"I've never had a customer come back and say the door we installed was too big,” says Jason Wing, a salesman for HydroSwing Inc. "You get one chance to install a door, so you're better off to go too big than too small.”

While some industrious farmers have enlarged existing doors in shops or machine sheds, "one chance” is generally the rule because of structural considerations related to door design.

"The size and type of door affects the structural design of the building,” says Larry Lembrich, senior vice president of Lester Buildings. "Some types of doors need stronger doorposts and some need to have the first couple trusses in from the door reinforced.

"We've found that, while some doors cost less than others, the cost of reinforcing the building to support the lower-priced door equals out in the end to the more expensive door,” Lembrich says. "You have to consider the cost of extrastructural reinforcement to the building, openers, extra electrical wiring and other accessories when you're comparing the cost of doors.”

Types of doors. Shoppers for big-access doors for farm shops or machine sheds have four basic options: traditional sliding doors, sectional overhead doors, bi-fold doors that fold horizontally in the middle and one-piece doors that hinge at the top.

The traditional sliding doors are valid options for machine sheds, but they are questionable choices for shops.

"Sliding doors are high-maintenance if they're opened and closed a lot,” Lembrich says. "If you've got a shop that doesn't get a lot of use, you might get by with sliding doors. But if you add insulation and lining to make a good shop door, you're adding weight, and that makes it heavier to open and close and puts more stress on the hardware.”

Sectional overhead doors have been the standard for garages and farm shops for decades. Door weight is an issue as farm equipment and shop doorways grow ever wider.

"To make wider doors, you have to use heavier struts and bracing to support the weight of each section when the door is open,” explains Chad Gillespie, a salesman for Overhead Door Company of Des Moines Inc. "Those heavier sections require stronger, heavier rails, so everything gets bigger, bulkier and more expensive.

"You can get sectional overhead doors up to 40' wide and 32' high,” Gillespie says. "The most common overhead door we installed in farm shops used to be 20' to 24' wide and 14' high. Now the norm is 30' to 36' wide and 16' to 18' high.”

Lost clearance. Gillespie notes that big sectional overhead doors reduce vertical clearances in buildings because of the heavier tracks and bracing needed to support the extra weight.

"You end up losing 30" to 36" of headroom if you don't plan ahead and make the sidewalls a little higher,” Gillespie says. "There are low-head-room track systems that require only 18" to 20" of headroom, but those designs put a lot of stress on tracks and require more maintenance.

"A 36'-wide, 18'-high sectional overhead door works good, but it's going to take heavier hardware, dual tracks and a stronger and more complicated opener system,” he adds.

Gillespie, who installed and repaired doors before moving to sales, recommends working with door company representatives long before it's time to install the doors.

"Especially in pole buildings, where there are 8' between trusses, it really helps if the builders put blocking and supports in the ceiling for the tracks and openers,” he says. "Knowing what kind and style of overhead door will be installed can save time and money and make a stronger installation when the door is finished.”

Moisture risk. Farmers who plan to power wash equipment just inside their doorway should install moisture-resistant electric motors and door rollers on sectional overhead doors.
"The steam and moisture causes problems if you wash a lot of equipment right under the door opener,” Gillespie explains. "We recommend motors and door rollers designed for car washes in that situation.”

Despite all of the considerations, sectional doors are an economical option for many farm shops.

"A good sectional overhead door is the economical choice if the door is less than 24' wide; it's an option if the door is less than 36',” says Lester Buildings' Lembrich. "Larger than that and you're probably looking at some sort of bi-fold or one-piece door.”

Mike Schweiss, founder of Schweiss Bi-Fold Doors, says: "Width isn't an issue for us. We're putting in a lot of 40' doors now, and aggressive guys are going to 50' doors. The biggest door we've built so far is 130' wide.”

Terry Albrecht, Hector, Minn., put up an 80'x150' pole building for machine storage with an eye toward using it as a shop in the future. He installed two 50'x18' bi-fold doors on opposite ends of the building for drive-through maneuverability.

"I started out wanting a big bi-fold and a smaller door, but it ended up being nearly the same money for two big bi-folds,” he says.

Bi-fold doors require only 24" of headroom, can be insulated to R-values equal to the sidewalls of buildings and use a variety of lifting mechanisms.

Albrecht's doors use straps, rather than steel cables, to lift each end of the door.

Cables or straps. "If the door has cables and accidentally comes down on a bucket or piece of equipment sitting in the doorway, the cable bird nests like a fishing reel, and it's a mess to get it untangled,” Albrecht says. "Aside from their not getting tangled, I like straps because as the strap wraps around the spool, the radius of the spool increases so the door rises faster. The door raises or lowers slow close to the floor, then faster as it gets closer to wide open.”

Bi-fold doors usually require stronger doorposts, reinforced end trusses and possible reinforcement of trusses inside the building. That is why bi-fold doors should be specified early in the design process so designers can incorporate adequate reinforcing.

One-piece doors are a second option for farmers who need mega-doors on buildings. One-piece doors hinge at the top and are most often opened through a self-contained hydraulic system.

"They're basically a wall that's hinged at the top that swings open,” Wing says. "Our average door in 2008 for farm shops is around 32' wide and 16' to 18' high. We can generally talk guys into 40' doors once they hear the details and think about it. Small grain platforms of 30' to 35' are common, and it's nice to have a couple feet extra on each side when you're moving them in and out.”

One-piece doors require less than 6" of headroom and can be insulated to the same R-value as other walls in the building. A downside of one-piece doors is their wide opening arc, which precludes leaving vehicles parked in front of a door as it's opened. They can also require a hefty truss on the outside bottom of the door that can freeze shut during heavy snowfalls.

Plan ahead. "There's a lot of variation in the design of trusses and end wall posts,” Wing says. "Our door attaches to the bottom of the end truss. Depending on the design, there may not be any need for reinforcing header or structural bracing.”

Lembrich agrees door selection should start early in the building process. "Different doors have different structural requirements and considerations for electrical wiring,” he says.

"It's very misleading to price a building and then price doors as stand-alone items. Structural reinforcing, closing systems, electrical wiring for the closers—they all have to be integrated to get the best possible price.”

You can e-mail Dan Anderson at

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