By Victor Lopez
The following is part two of a two-part series on the evolution of self-storage design and site-plan considerations for a new era.
The Metal Grid
In today's industry, the most economical and versatile structural design system for storage buildings is the 5-by-10-foot light-gauge metal grid. To understand this basic design, visualize the typical long and narrow building. At 10-foot intervals along the building length is a load-bearing wall, which consists of metal columns every five feet, connected with metal panels that form the side partitions of the units. At the top of the columns, purlins are connected and run the length of the building, supporting the roof panels. The back walls of the unit are attached to the columns of the bearing walls at the desired unit depth. This simple design allows for quick construction of the building and also spreads the weight of the structure evenly across the floor, allowing for a more efficient and economical design for the foundation.
Additional advantages of the 5-by-10-foot grid system include the variety of options for columns between doors and exterior walls. Columns between the doors can be concrete-filled block masonry, concrete tilt panels or heavy-gauge metal-finished with a textured paint. These same materials are used for exterior walls and, most often, in combination with dummy door panels or a variety of metal sheathing. For eye-catching curb appeal at the front of the facility, the grid framing can be easily blended with more traditionally framed exterior walls that support block and brick veneers or stucco.
Don't forget about the options available with coiling doors and the small area above the door called the header or filler panel. The most common choice is to use a corrugated metal panel like that of the door in the same or a different color. Header panels are also seen in various types of metal panels, pre- finished or textured and painted in the field. Finally, the header panel may be required to be a structural component of the building. Concrete-block masonry or concrete tilt-wall panels are commonly used to satisfy the requirement.
Roofing Systems
Roofing systems have also evolved into a more durable and maintenance-free component of storage building design. The standing-seam metal roof system has several advantages over the older screw-down roof. With the standing-seam roof, there are virtually no exposed screws across the span of the building, eliminating potential leaks from weathered fasteners. Metal roofing panels are available in the standard galvanized finish or a variety of colors. When properly supported by purlins and the 5-by-10-foot framing system, a 26-gauge roof panel is all you need. Right along with the roof panel is the vinyl-backed roof insulation. This is an integral part of the roof system and serves an important role--even in buildings that are not climate-controlled. Without the roof insulation, the underside of the roof panels are subject to condensation--especially in areas with high humidity--allowing water to collect inside the units.
Multi-Level Designs
As discussed in part one of this article, more and more of the sites available for self-storage dictate the use of split- and multi-level designs. The advantages to these designs are that they increase net-leasable square footage while reducing the basis for land cost, facilitating climate-controlled square footage and allowing your facility to become part of the skyline. The same principles of single-story building design also apply to split- and multi-level storage buildings. However, as your building goes up, you must consider some additional parameters.
In split-level storage buildings, there are a few additional design considerations over single-story designs. With the exception that you will add interior hallways, the upper level and roof system are the same. Retaining walls will be required where waterproofing and backfill are critical components. Load-bearing walls use stronger and/or additional columns to support the second-floor metal decking. This metal decking becomes the floor pan into which the second-floor concrete is poured.
Multi-level storage designs have more considerations, yet they remain extremely cost-effective when compared to most commercial multistory buildings. The need for more hallways and common-area spaces will reduce your coverage of net-leaseable to gross square footage to about 72 percent. Fire sprinklers and monitored fire-alarm systems increase building cost and space requirements. Each floor will require control rooms and additional overhead space to accommodate piping and sprinkler-head clearances. Elevators also require mechanical rooms, as well as areas below the foundation and above the roof to accommodate the shaft. Stairwells and stairs also add cost and consume space.
Storage Building Design Products
Now that we have discussed the framework and exterior walls of storage buildings, let's take a look at design products that make up the rest of the facility. When designing interior hallways, there are several factors that can go a long way towards a comfortable, user-friendly atmosphere.
To provide your customer with the best access to his unit, use swing doors for units that are five or fewer feet wide, and roll-up doors for all others. For longer life, low maintenance and easy operation, choose a coiling door with axial ball bearings and quick tension-adjustable axles. Wall sections are typically metal panels and, whether they are corrugated or smooth, a light glossy color should be used for the best light reflection. Consider using mitered corner guards and kick plates to help your hallways from looking beaten and worn.
Security products have also experienced significant evolution in this industry. With security being one of the major reasons your customers will rent at your facility, these products deserve ample consideration. The first impression your security system will make is with your office control panel. This is the best way to demonstrate your security system is several layers deep. Fencing and entry control gates represent the first layer. The software available for entry control offers a variety of ways to monitor everyone passing through your gate.
Adding cameras at all perimeter drive aisles and entry gates is your second layer of security. Place additional cameras at interior hallways and in the front office. Another level of security that is rapidly gaining popularity is individual unit alarms. These door alarms have undergone major advancements in reliability and interoperability with the total security package. Yet, at a cost of about a dollar per gross square foot, you might consider using them in select areas. Wrap up the security system with customer conveniences such as intercoms and music piped into hallways and common spaces.
In conclusion, the evolution of self-storage has taken this industry from hit-or-miss backyard sheds to big business retail stores. Today, as we develop sites and design storage buildings, we realize our industry compels us to be ever mindful of ways to improve. Whether it is adding an ancillary business service to the office or using modular aerated concrete components for firewalls, we need to continue designing for the new era.
Victor D. Lopez is vice president of National Development Services Inc. (NDS) of Bulverde, Texas, which has designed and built more than 150 self-storage properties since 1980. The company's accomplishments include receipt of the "Facility of the Year" award in 1990, 1991, 1994 and 1996, and the "Design Excellence" award from Mini-Storage Institute in 1992. For more information, visit www.ndsinc.com.