Closed-Cell Spray Foam Offers Significant Benefits to Metal Buildings

Metal and Closed-Cell SPF share similar characteristics—for example, both are lightweight, durable, and adaptable to a range of circumstances.

The use of ccSPF can impart a number of high-performance attributes to metal roofing and cladding assemblies, from high R-value thermal insulation and good acoustical performance to wind uplift resistance and increased racking strength.

Replacing metal roofing and wall panels may cost $10 to $13 per square foot. In contrast, a ccSPF application can range from $3 to $5 per square foot—less than half the cost—and provide extra insulation and waterproofing, in addition to other benefits.

When properly designed, constructed, and maintained, a metal building or roof assembly should last 15 to 30 years before requiring serious maintenance. Nevertheless, thousands of metal building and roofing assemblies need retrofit or replacement long before the end of their expected lifespan.

Factors critical for energy efficiency and durability must be addressed in new and retrofit construction.

These include:

• Thermal shock movement;
• Moisture condensation;
• Uncontrolled air movement;
• Thermal bridging; and
• Radiant heat absorption.

Closed-cell sprayed polyurethane foam can help solve many of these concerns. The material is sprayed onto a surface as a liquid. Within seconds the foam—while still in a fluid-like state—expands 30 to 40 times its original volume to form a lightweight insulation, filling cracks, crevices, and areas difficult to reach with other products.

The material can be installed as a roofing system (or insulated exterior wall covering), or applied to the interior walls and ceiling. Both options have distinctive benefits. Various factors determine which system is appropriate for a specific metal building project.

Building owners and specifiers are often faced with the question of where to install the ccSPF—inside or outsie. In some situations, the answer is obvious; in others, it can be difficult to determine.

Applying ccSPF to the building interior controls structural movement better, as it emails gluing the trusses, joists, beams, and other elements directly together. The potential for poor weather conditions, such as high winds or rain, may also make interior application preferable. Conversely, installing insulation on the outside of the building provides enhanced energy efficiency, as it eliminates thermal bridging.

In cases where there is much activity inside a building—such as ongoing operations, equipment, racks, storage, furnishings, and occupied areas—the most appropriate way to use ccSPF is applying it outside the building envelope. Overspray preparation (i.e. covering or masking off areas or objects that might accidentally be oversprayed) may also affect the preferred point of application.

To determine the appropriate type of ccSPF application, basic building information is required, such as location, climate, intended use, and occupancy. Questions pertaining to major concerns or challenges should be answered. Suitable questions include:

• Are there leak, moisture, or condensation issues?
• Is energy efficiency a major concern?
• Will there be considerable work disruption from an interior application?
• Is overspray prep needed before the application?
• Is additional structural strength desired, and if so, of what type? For example, if the building is in a hurricane-prone zone and the owner would like to reinforce the whole building against wind damage, what are the options?
• What type of substrate preparation is required?
• Are there surface or assembly preparation challenges? For example, is rust treatment or replacement of fasteners or welds required?

After considering the building requirements and desired changes, the building owner should then review the characteristics and benefits for each type of ccSPF system. Regardless of whether the building owner decides to install a ccSPF system outside or inside a metal building—or use a combination of the two – research and historical evidence suggests the application provides a range of benefits