The most common building type Jordan has been called upon to convert is a warehouse, but he frequently converts office buildings, retail buildings, supermarkets and, yes, even hotels. “Since conversions involve existing buildings, we find the zoning approval process to be generally easier than obtaining approvals for new ground-up facilities,” he says. “Existing buildings are known to the community and often less threatening to neighbors than a proposed new facility with its unknown impacts.”
Also helping with easier zoning approvals is the traffic impact. Self-storage projects generate significantly less traffic than a warehouse, retail space or office building, so the community will benefit in traffic reduction.
Jordan says the access and design of efficient and convenient loading facilities are essential for the development of a successful self-storage conversion since they don’t have the traditional drive aisles for access to the units. For multi-story conversions, vertical access with elevators replaces drive aisles. Many warehouses have a 20-foot interior height and can accommodate an another floor, so the addition of a second floor is very common. A 30,000-square-foot warehouse becomes a 60,000-square-foot self-storage project.
Since 50 percent of customers will have storage space on the second floor, the elevator and loading facilities are key. Elevators should have large cabs. Typically, we use 5,000-pound elevators and specify 10-foot-high cabs so large items such as a couch can be easily loaded. The travel distance to the most remote unit should not exceed 175 feet, and elevator lobbies should be a minimum of 10 by 10 feet to allow for the maneuvering of carts.
“Most buildings suitable for a conversion to self-storage do not have sufficient structural systems or load-carrying capacity, so the structural impacts need to be evaluated by a structural engineer,” says Jordan, offering this example. A two-story office building will usually have a second floor designed to carry a load of about 50 pounds per square foot. Self-storage requires 125 pounds per square foot, so the structure will have to be modified to carry the increased load.
“Usually, adding a beam line to reduce the span of the structure supporting the floor will achieve the desired load,” Jordan says. “Where a new second floor is added, such as in a warehouse, bearing-wall partitions can be used to support the new second floor.”
The existing foundation may or may not be adequate to carry this load, Jordan notes. “If the existing foundation proves inadequate to take the increased load, one method we use is to over pour the slab to increase its thickness and, hence, take the new load. Sometimes in older buildings we get lucky and find thick foundations that will take a new floor load.”
Everett Downtown Storage in Everett, Wash., before (left) and after.