By Steve Goold

lat roofs are a popular, cost-effective choice for storage facilities because they offer lower construction costs, easier maintenance access, and usable space for HVAC units. The flat, stable, and safe surface makes it easier for repair crews to inspect and maintain the roof, reducing labor time and costs.

Flat roofs can accommodate a wide range of roofing materials, from built-up roofing (BUR) to single-ply membranes such as polyvinyl chloride (PVC), as well as metal, concrete, and thermoplastic polyolefin single-ply membrane, for example, and are often designed with a slight slope to facilitate water drainage.

Proper drainage systems can effectively direct rainwater away from the roof, minimizing the risk of leaks and water damage. However, accumulating water finds a weak spot to penetrate into permeable materials or seams that aren’t well-sealed. As water accumulates, it deteriorates most traditional roofing materials: adhesives in single-ply roof systems lose their grip, steel equipment supports are corroded, and oil solvent components of roofing asphalts seep into the water, leaving the remaining membrane brittle, cracked, and leaking as the pond grows, thus accelerating the roof’s aging. Ponding also adds more weight onto the roof and unfortunately remains until the water evaporates.

Fortunately, a spray polyurethane foam (SPF) roofing system builds resilience into the structure. The seamless, fully adhered, insulated membrane combines slope, insulation, and waterproofing in one field-applied system, becoming the evolution of the modern roof.

SPF roofing provides a seamless, continuous layer over the top of the structure. The roof system performs numerous functions: vapor retarder, weather-resistant barrier, air barrier, and continuous thermal insulation. This roofing system may be applied as a new roof or over most existing roofs, providing a cost-effective retrofit solution.

SPF offers a seamless, monolithic barrier, delivering the highest insulation value per inch of any roofing material (R-6.9 per inch). This system corrects poor drainage by varying application thickness, and self-flashes around roof penetrations. Sprayed as a liquid, SPF expands to create a seamless, self-adhering membrane that completely eliminates joints and seams, the most common sources of roof leaks. It’s easy for professionals to install, it’s affordable (numerous studies have shown that the ROI on spray foam systems can happen in as little as five years or less in energy cost reduction), and it has superior longevity over other roofing systems. But property owners might not know how much protection an SPF roof can provide for their building. For example:

• Durability – One of the best features of spray foam is that it insulates the building, mitigating excessive expansion and contraction due to changing outside temperatures. This characteristic gives it unparalleled durability. Contractors can install spray foam in almost any climate or harsh environment and it will hold up well.
• Seamless Surface – SPF is a continuous system that fills in cracks, holes, corners, and along the roof’s base. Spray foam has no exposed seams, so there is less chance for water to penetrate through to the deck. It is a durable cellular insulation that protects the roof from moisture and air. Building owners never have to worry about cracking or splitting in a single-ply membrane.
• Sustainable – SPF as a roofing system is a low-waste and low-labor assembly, providing an efficient installation method with less disposal and minimal tear-off costs. With proper maintenance, the SPF roof system can be renewed at the end of its service life by re-coating the existing elastomeric coating. SPF features ultra-low global warming chemistry that reduces the carbon footprint in its roofing systems.
• Meets Building Codes – SPF is ideal for meeting all commercial building codes. Coated foamed roof assemblies can meet Class-A and Class-B fire performance, which is especially beneficial in metropolitan areas where building codes are stricter.
• Reduces Heat Absorption – Self-storage flat roofs face severe heat absorption challenges due to their large, unshaded surface areas. However, SPF’s insulation and light-colored roofing surface can reduce the amount of air conditioning needed by reflecting considerably more sunlight—and therefore heat—than conventional, dark-colored roofs.

Opened in Pasadena, Calif., in 2001, STORBOX Self Storage currently has over 2,000 tenants and also includes The Wine Grotto. The complex is the largest self-storage and wine storage facility in the San Gabriel Valley. STORBOX is family-owned and operated with management and investors in the Pasadena and South Pasadena communities. The Wine Grotto provides a temperature- and humidity-controlled wine storage environment.

The property includes six buildings with a variety of roof systems. After 25 years, almost all of the roofs recently needed renovations. Last year, Brett Barnard, STORBOX owner, had a number of installation-process concerns from the roofing contractor who was retained to apply a SPF on a BUR system that already had spray foam and now needed a restorative coating over this section. Fortunately, Barnard connected with the SPF manufacturer and the Southern California sales manager who, with decades of industry experience, walked through the installation process, alleviating any apprehensions.

“It’s essential that our buildings’ roofs are waterproof to protect tenants’ important possessions. Talking with the manufacturer’s experienced sales manager helped me understand the entire process that would occur and got the project back on track,” says Barnard.

The monolithic spray foam is applied directly to the roof surface, allowing for filling in the known ponding areas and rain to flow to the channels and drain more effectively. Every inch of SPF roofing is engineered for performance; the insulation, slope correction, adhesion, and weatherproofing work together as one resilient system.

Prior to applying the SPF system, the team first used a roof vacuum to remove all of the loose gravel and dust; they then applied a waterborne modified acrylic neoprene asphalt primer to promote better foam adhesion and prevent blistering. Next they applied the SPF, which rapidly expanded into a dense, closed-cell insulation and waterproof barrier. And lastly, an acrylic elastomeric top coat was applied over the cured SPF to protect against UV degradation.

“Because the California sun is relentless on roofs and to meet the state’s rigorous sustainability requirements, I knew that this manufacturer’s SFP and acrylic products would be the ideal choice for this project,” says Barnard.

The spray primer, foam, and roof coating as a retrofit system was installed with minimal interruption because the contractor didn’t need to tear off of the existing roof, saving STORBOX time and money. Additionally, this virtually maintenance-free system includes a solar reflective coating with embedded granules that increases the surface durability of roofs. California building requirements like Title 24 cool roofs can be challenging, however, the spray foam roofing system is actually renewable because it can be recoated with additional roof coating as the system comes to its surface life in 10 to 20 years. It’s the only roofing system that is designed to be sustainable and to last the lifespan of the building.

Barnard has been so pleased working with this manufacturer and the results of this project that he will be using SPF for other building retrofits in the future.