Metal-roof systems are popular in self-storage building designs for a variety of reasons including durability, ease of maintenance and low cost of installation. When built and installed correctly, they can last 20-plus years, which is a success for owners who don’t want their profit margin eaten up by large capital expenses like roof repair or replacement.
What’s critical to understand, however, is not all metal roofs are the same. They perform differently depending on a variety of factors. The same system installed in two dissimilar parts of the country may function in very unique ways. This is why it’s important your roof is installed by an experienced contractor with a true understanding of the various roof styles and how they behave.
In this article, we’ll discuss the two most popular types of roof systems used in self-storage facility design and their pros and cons. First, let’s talk about typical roof features.
There are numerous types of roof panels used in self-storage, and they come in various widths, lengths and thicknesses. You also need to think about insulation, slopes, fastening techniques, finishes and coatings. Facility operators with a baseline understanding of these elements will be better equipped to ask questions when considering a new or replacement roof.
First, take panel length and thickness. The most common thicknesses are 24 and 26 gauge. Typically, 26-gauge panels can’t be too long because of a waving effect that occurs after they’re installed. A 24-gauge panel is stronger and can be used in longer lengths. This reduces the waving effect and the number of horizontal seams needed.
Next, consider types and finishes. Metal roofing can contribute to a self-storage facility’s aesthetic appearance, depending on what you choose. The more slope used, the more noticeable the roof is from the ground. You can achieve different looks by changing the width of the seams between the panels and using various seam types: striated, corrugated, flat or ribbed. Panel profiles can be stamped to create a look of a shingle, tile or shake. They also come in many colors and finishes, including a plain mill finish. Common types of mill finishes include aluminum, galvalume, coated steel, stainless steel and copper.
The most expensive and longest-lasting metal roofs are stainless steel and copper. Aluminum, galvanized and galvalume panels can be mill finished or coated/painted. When choosing, pay attention to the warranties. Those for metal panels include a watertight/finish warranty or just a finish warranty. The combination of the metal type and finish usually correlates to the length of the finish warranty. Make sure you look at the warranty content addressing coverage and duration.
There are two primary types of metal roofs used in self-storage design:
Exposed-fastener metal roofing is widely available and easy to install. It’s comprised of metal panels fastened to the roof’s vertical and horizontal seams with screws, and neoprene or rubber washers. It’s visually appealing and cost-effective but doesn’t accommodate for roof expansion and contraction due to wind or changes in temperature.
Concealed-clip, standing-seam roofing consists of panels that are mechanically seamed. The clips are below the panel and attached to the purlin. The panels slide onto them. This eliminates the need for fasteners in the vertical seams, which in turn, allows the panel to move with expansion and contraction. This roof type is more expensive to install, but it offers the benefit of a longer, watertight life.
Deciding between the two types often comes down to budget, expected duration of ownership and location of the business. Tolerance for maintenance and plugging leaks are also factors. Following are the distinct advantages and disadvantages to both.
On the plus side, this roof type is less expensive. The cost savings compared to a concealed-clip roof is largely driven by the wider, thinner panels used—up to 36 inches wide and 26-gauge thickness—which cost less. There’s also less labor required during installation due to the much faster lap technique and fastening of verticals. Provided the roof has a good finish and is correctly installed for its environment and climate, the system also holds up to weather conditions relatively well.
On the other hand, exposed fasteners require installers to make a lot holes in the roof, which can create problems. Water penetration is one of the most common issues with this system. If a fastener is tightened too much or too little, it’ll cause a leak. Since the system doesn’t accommodate for the expansion and contraction of the metal, over time, the fastener will become augured and cause seepage. With so many roof holes needed for this system and leaks seemingly inevitable, it’s unlikely to find a long-term, watertight warranty.
Exposed fasteners require more frequent maintenance, so you must keep a closer eye on the roof. Regular inspections are recommended to check the state of fasteners and replace those in poor condition before they cause a problem.
Finally, low slopes aren’t possible with an exposed-fastener roof. More than one inch per foot of slope is recommended, as it better allows water to shed from the roof and helps prevent ponding. If you desire a lower slope, you don’t want to go with exposed fasteners.
A roof with exposed fasteners
Concealed-Clip Standing-Seam Roof
With a concealed-clip metal roof, one of the obvious advantages is your fasteners aren’t exposed to UV rays, moisture, wind and other elements that can cause them to wear over time. There’s also no need to punch holes in the metal panels. Aesthetically, these roofs just look sleeker. There are also longer-term watertight warranties available, as you aren’t punching those problematic holes in the roof.
A standing-seam roof allows for expansion and contraction, and the need for maintenance is less frequent with concealed-clip systems. Of course, upkeep is still essential and should be performed by a professional contractor to ensure the roof achieves the durability for which it was designed. Finally, though it’s recommended to have a roof slope of one inch per foot or greater, manufacturers offer slopes as low as one-quarter inch.
As you might suspect, a concealed-clip roof is more expensive, though it isn’t always the highest priced system when compared with metal shingles and other stamped-metal materials. It involves a more labor-intensive installation, and there are fewer qualified contractors available. The system can be complicated and tedious to install, requiring careful craftmanship and a precise-multi-step process. Experienced contractors with a proven track record can be difficult to find. Ultimately, though, you’ll be rewarded with a longer-lasting, lower-maintenance roof.
An example of a roof with concealed clips
Pay Now or Later?
Regardless of which metal-roof system you choose, they all offer the core benefits of durability, weather-resistance and environmental-friendliness. Metal has the capacity to resist strong winds and shed water and snow. For the environmentally conscious, there’s much less waste produced with metal systems compared to asphalt shingles, which need to be replaced far more frequently. Even with the lower price associated with these roofs, the finish should last 20 years or more with proper care and maintenance, which is another plus.
Understanding basic roof design can help self-storage owners make smart decisions when balancing the price of installation against the total cost of ownership. Since metal roofs all perform differently, choosing a system often results in a pay-now vs. pay-later judgment call.
Anthony Vross is a co-owner of Simon Roofing, a national roofing manufacturer and contractor. The company provides roof-asset management, evaluation, preventive maintenance, repairs, restoration and replacement. For more information, call 888.353.7178; visit www.simonroofing.com.