Multilevel Design Considerations
By Cecile Blaine
Twenty years ago, the mere mention of self-storage conjured up an image of a long line of one-story, garage-like units. Today, however, the typical self-storage facility might be housed in a one-story, two-story or even sky-scraping building.
Facilities are growing up.
The very reasons for going to a multilevel sometimes dictate various elements of the building's design. Usually more expensive land creates the need to build up rather than out, as pricier land requires a facility with more earning potential than a single-story facility--more units and greater square footage in order to bring in the revenue.
"What makes the multistory more attractive, of course, is the cost of land," says Herman Menze, a self-storage facility designer based in Tempe, Ariz.
Vincent High, a sales representative with Pioneer International Steel Inc. in Austin, Texas, sees a trend in the development of multilevel facilities. "I am starting to see more expensive sites, sites located near higher-end residential communities," High says. Those facilities say a great deal about the changing market. "Whereas the property itself is fairly expensive, people are willing to pay a little more on the dollar to get their unit closer to them."
It makes sense that developers who build on expensive land will spend more on their facility and will charge higher rental rates. "The people who are going to spend the money on a project--on an expensive piece of property where they need to build up--generally are going to go high-end. They are going to offer climate control. They are going to offer all the finer features that you'd find in a self-storage building."
The height of a facility is directly proportionate to zoning regulations. In fact, if self-storage is still unknown to many planning and development departments, multilevel facilities confuse them even more.
"Generally, on the multilevel projects, you need to get approval from the city," High says. "And you are going to have to get an architect.
"One thing we find in the multilevel buildings is there is a bit more planning involved and a lot more of an approval process. You don't want to get too involved in a project only to find out that it won't be approved. So, there is a lot of pre-approval that goes on through the counties or cities before you get to the builder. You do have to keep flexibility in mind."
Breaking the Code
Many aspects of design are pre-determined by building codes and regulations--whether national, statewide, county or local. The facility's location dictates its building codes. For example, the Universal Building Code (UBC) reigns in most of the western states, Building Officials' Conference of America (BOCA) is used in the eastern United States, while the state of New York has a code all its own. These national codes determine such specifications as roof load, stairwell configuration and the minimum distance between a unit and the nearest stairway. New York, on the other hand, is particularly quirky because it is the only state that requires facilities to have fire hatches with a railing to the roof, according to Jamie Lindau, sales manager of Trachte Building Systems Inc. of Sun Prairie, Wisc.
"There are a lot of particulars in each state," says Lindau.
The Americans With Disabilities Act (ADA) also requires public buildings to accommodate the handicapped, whether that be with ramps, parking, special bathrooms or all of the above.
Local fire codes affect sprinklers, fire walls, fire doors and other related specifications, says High. As a general rule of thumb, he says, a building larger than 40,000 square feet will need sprinklers and anything more than 16,000 square feet will require fire walls approximately every 3,000 feet.
One thing that Menze likes to point out is the love/hate relationship with sprinklers. "The fire departments love them," he says. "The managers generally hate them, because they are more afraid of water damage than fire damage. So, as a practical matter, I think the operators have to get accustomed to them."
In the design of Squaw Peak Mini-Storage in Phoenix, which has one three-story building, Menze was required to install one sprinkler head for every unit in the facility. The upside of having so many sprinklers meant no fire walls were needed.
Building height is frequently regulated by local authorities, but there are ways to be creative with restrictions. For example, Menze faced a 24-foot building height restriction on the Phoenix facility he designed. "So, how do you get three floors in 24 feet?" he asks with a laugh. He did it by designing a basement into the building with ground-level access, which brought it to 24 feet and gave him the number of units needed to keep to the owner's pro-forma.
"One of the things we did was put the basement two feet above ground, so our ground-level floor is two feet up," says Menze. "That way you can back up and unload a pickup."
Others, like Lindau, say that basements bring on other problems. "With a basement, you have the potential concern of water leaking in, the musty smell," he explains. "Sometimes owners will use climate control on that lower level to help take out that musty smell." But more often than not, he says, "you've got a problem. It's a basement; it will smell like a basement."
Mix and Match
Building on more expensive land for a wealthier customer base often means building a facility with a unit mix that is lopsided toward smaller units; larger units are usually placed on the ground floors, with the greater number of smaller units, such as 5-by-5s and 5-by-10s, built on the upper floors.
For example, High is currently working on a facility that includes a three-story building in which the entire first floor is divided up into 10-by-20s with the second floor housing the 10-by-10s, 5-by-10s and 5-by-5s.
Adding levels to the old model of the self-storage facility means that the owner must provide additional amenities to help the customer get around, such as dollies, carts and perhaps a loading dock.
When taking a facility from a flat string of boxy units to a stacked formation, the question of having an elevator comes into play.
In his experience, Lindau says a lift is usually included in the design of a two-story building, while elevators are almost always built into three-story facilities. The cost difference is approximately $20,000 for the lift, compared with $50,000 for the elevator, he says.
On the other hand, High says not all Pioneer's two-level projects have elevators or lifts. The bottom line, he adds, is that owners should want to make it as easy as possible for customers to get to their units, while staying within the budget.
Just the presence of an elevator points to an upper-scale facility, a sign of class and convenience. It's just another amenity that makes the difference between an average facility and one that caters to a customer base that can support higher rental rates.
Whether they are required or not, elevators can be added to a facility as an architectural point of interest and to add dimension, as Menze illustrated in his latest project.
The structure of a multilevel facility usually has some subtle changes from that of its one-story brother.
Some builders say that the foundation for a facility with multiple levels doesn't differ greatly from a single-story building. Others, like Trachte's Lindau, note the increase in materials and change in the footings.
"If you only go one to two stories, you use more re-bar, more shovel footings," he says. "You typically are not allowed a floating slab. You need a frost wall or a trench-wall footing instead. If you were constructing a metal building up north, you do not need a footing. But when you go to a two-story, you usually cannot do that. You have to go to the frost line."
As facilities grow taller and taller, construction materials are increasingly restricted. For example, more flammable materials such as wood are frowned on as the facility design grows.
Likewise, whereas single-story facilities sell convenience in terms of distance from the customers' cars, provided by their exterior entrances, upper levels of multilevel buildings are designed almost exclusively with interior hallways. That is done for a number of reasons, the strongest of which is saving space and money for climate control.
At Squaw Peak Self Storage, the multilevel facility Menze designed, he has created door mullions, headers and end panels out of structural members in order to strengthen the hallways. "This way, you can take a mullion and hit it with a sledgehammer and you are not going to hurt it," he says.
In order to maintain higher rents and attract an upper-scale clientele, multilevel facilities--with interior hallways on the upper floors--are perfectly set up to offer climate control. Larger, non-climate-control units with the roll-up doors are typically placed on the ground level with street access. Then, the smaller, upper-level units located on interior hallways have climate control.
"The rent you get is 10 to 20 percent higher," attests Menze, who put evaporative coolers on the ground floor and upper level and standard air-conditioning units in the basement of Squaw Peak Self Storage to reduce the cost of cooling.
In a world where convenience is everything, climate control is an added incentive to get customers to take those extra steps from their cars that those upper floors require. "They want to drive up to their unit, they want to walk two feet and open the door," he points out. "Anything more than that is a hassle."
Today's multilevel facility design reflects several different movements in the market: the scarcity of attractive rural sites, a move to urban markets and a demand for a product located closer to home. The end result has been higher standards than ever. Multilevel design is subject to more building regulations and stronger construction requirements. It has followed a trend in interior over exterior hallways and has offered the most sophisticated amenities the industry has known.
So, at least in the case of multilevel facility development, what goes up, doesn't necessarily come down--either in price or in quality.