SPF Spray Polyurethane Foam Roofing Systems

What Is SPF Spray Polyurethane Foam Roofing?

Spray polyurethane foam (SPF) roofing is a fluid-applied system that combines two chemical components, isocyanate and polyol resin, which react on contact to create a rigid, closed-cell foam layer directly on the roof substrate. Once cured, the foam is protected by a durable elastomeric coating that shields it from ultraviolet radiation and weather exposure. The result is a monolithic, fully adhered roofing membrane with no seams, joints, or fasteners, eliminating the most common points of failure in commercial roofing systems.

At Windward Roofing & Construction, we have been installing SPF roofing systems on commercial and industrial buildings across the Midwest and beyond for over four decades. Our certified applicators work with leading manufacturers including Johns Manville and ERC Systems to deliver spray foam solutions that outperform conventional roofing in both thermal efficiency and long-term reliability.

How SPF Roofing Works

The SPF installation process begins with thorough surface preparation. Our crews clean the existing roof substrate, remove debris, and address any standing moisture issues. Once the surface is ready, the two-component foam is sprayed through specialized heated equipment at precise temperature and pressure settings. The liquid components expand on contact, rising to approximately 30 times their original volume within seconds, and cure into a solid, rigid foam layer.

The foam is typically applied in multiple passes to achieve the desired thickness, which usually ranges from 1 to 2 inches for roofing applications. Thickness can be varied across the roof surface to create positive slope for drainage, filling in low spots and eliminating ponding water issues without the need for additional tapered insulation. After the foam has cured, a protective elastomeric top coat, most commonly silicone or acrylic, is applied in one or two coats to provide UV protection and weather resistance.

Self-Flashing and Seamless Coverage

One of the most significant advantages of SPF roofing is its ability to conform to virtually any roof geometry. The liquid foam self-flashes around penetrations such as HVAC units, vents, pipes, skylights, and parapet walls, creating a watertight seal without the need for separate flashing components. This seamless characteristic eliminates the hundreds of linear feet of seams and laps found in traditional membrane systems, where the vast majority of leaks originate.

Energy Efficiency and R-Value Advantages

SPF delivers an R-value of approximately 6.5 per inch of closed-cell foam, the highest of any roofing insulation material commercially available. By comparison, standard rigid polyisocyanurate board insulation provides an R-value of roughly 5.7 per inch, and extruded polystyrene offers about 5.0 per inch. This means a building can achieve greater thermal resistance with a thinner SPF application, which is particularly valuable when roof height clearances or load-bearing capacity are concerns.

The energy savings associated with SPF roofing are substantial. Because the foam is sprayed directly onto the substrate with full adhesion, there are no gaps, voids, or thermal short circuits that allow air infiltration. Traditional insulation boards, which are mechanically fastened or adhered in sections, inevitably leave small gaps at joints and around fasteners where conditioned air escapes. Studies have shown that SPF can reduce heating and cooling costs by 30 percent or more compared to conventional insulation approaches.

When paired with a highly reflective white or light-colored elastomeric coating, SPF roofing also reduces the urban heat island effect and qualifies for cool-roof ratings. The reflective surface bounces solar radiation away from the building, keeping the roof surface significantly cooler than dark-colored alternatives and further reducing cooling loads during summer months.

Ideal Applications for SPF Roofing

SPF roofing systems are particularly well-suited for a wide range of commercial and industrial building types across the markets we serve in Illinois, Wisconsin, Michigan, Indiana, and Florida. The most common applications include:

• Warehouses and distribution centers with large, open roof areas where seamless coverage and superior insulation provide maximum energy savings and eliminate maintenance on thousands of linear feet of seams.
• Manufacturing facilities with complex rooftop equipment installations where the self-flashing capabilities of SPF simplify waterproofing around numerous penetrations.
• Cold storage and refrigerated buildings where the high R-value of SPF prevents condensation and thermal bridging, protecting both the building envelope and stored products.
• Retail and office buildings where occupant comfort and energy cost reduction are priorities, and where the lightweight foam adds minimal structural load.
• Re-roofing projects where an existing roof substrate is structurally sound but needs improved insulation and waterproofing, allowing SPF to be applied over the existing system without a costly tear-off.

SPF Roofing Over Existing Systems

One of the most cost-effective advantages of SPF is its ability to be installed over many existing roof systems. Whether the current roof is single-ply TPO or EPDM, built-up asphalt, modified bitumen, or even metal, SPF can often be applied directly over the existing membrane as long as the substrate is dry and structurally sound. This eliminates tear-off labor and disposal costs, reduces project timelines, and keeps tens of thousands of pounds of roofing material out of landfills. Windward Roofing performs thorough moisture surveys and substrate evaluations before recommending an overlay to ensure the existing roof is a suitable base for the new SPF system.

Durability and Long-Term Performance

SPF roofing systems are remarkably durable when properly installed and maintained. The rigid closed-cell foam provides excellent resistance to foot traffic, hail impact, and wind uplift. Because the foam is fully adhered across the entire roof surface, there are no edges or seams that can be caught and peeled back during high-wind events. SPF systems have demonstrated superior performance during hurricanes and severe storms, making them an excellent choice for our Florida market as well as the Midwest, where severe weather is a regular concern.

The protective elastomeric coating is the component most exposed to the elements. Over time, this coating will weather from UV exposure and normal wear. However, the beauty of an SPF system is that it can be restored with a new top coat application every 10 to 15 years, effectively renewing the roof without replacing the insulating foam layer. This recoat cycle can be repeated indefinitely, meaning an SPF roof never needs to be torn off and replaced, only recoated, which significantly reduces lifecycle costs.

SPF Roof Maintenance

Maintaining an SPF roof is straightforward and cost-effective. Windward Roofing recommends biannual inspections, typically in spring and fall, to identify any surface damage from impacts, animal activity, or weathering. Minor punctures or abrasions can be repaired quickly with compatible caulk or a small foam patch, and these repairs restore the monolithic integrity of the system.

Our maintenance programs include detailed inspection reports, photo documentation, and prioritized repair recommendations to keep your SPF roof performing at peak efficiency throughout its service life. Proactive maintenance extends the intervals between recoat applications and helps building owners budget accurately for future roofing expenses.

Why Choose Windward Roofing for SPF Installation

With over 40 years in commercial roofing, Windward Roofing & Construction brings the experience and manufacturer certifications required for a quality SPF installation. Our crews are trained in the precise temperature, pressure, and application techniques that determine the quality of the finished foam. We work with industry-leading material suppliers including Johns Manville and ERC Systems, and our installations are backed by manufacturer warranties that provide long-term peace of mind. From initial roof evaluation to final inspection, our project management team ensures every SPF installation meets the highest standards of workmanship and performance.

Frequently Asked Questions