Insulate and Air Seal in One Easy Step

As the mercury drops in winter and rises in summer, it’s important to keep your home or building comfortable year-round. Installing both an insulator and an air barrier is the most effective way to maximize your structure’s energy efficiency. Spray foam insulation may be the ideal solution—especially for homeowners wondering “what is spray foam insulation” or “is spray foam insulation worth it” in colder regions.

How Spray Foam Works

Spray foam is a dual-acting product that insulates and air-seals in one application. It’s sprayed on as a liquid and quickly expands to fill a space, creating an air barrier and insulator that keeps energy in and moisture, allergens, and pollutants out—answering the common question of how does spray foam insulation work and why air sealing with spray foam is so effective.

Spray-foamed stud wall and ceiling with several window spaces covered by white Tyvek from the exterior.

Air leaks are inevitable and not always found in easy-to-reach spots. Because spray foam adheres to the materials it is applied to, it’s ideal to utilize spray foam for attic insulation, basement walls, rim joist insulation, and all those small or hard-to-reach spots. It’s also widely used for crawl space insulation, helping create a continuous air seal in colder climates where insulation for cold climates is critical.

Types of Spray Foam

There are two types of spray foam: open cell and closed cell. Both insulate and air seal in a single step, but each performs differently. They also compare differently against alternatives like fiberglass, blown-in, and cellulose.

Open-cell Spray Foam

  • Softer and more flexible

  • Dampens sounds, is vapor permeable, and eliminates air infiltration

  • Expands to 100-120 times its size when applied

  • Has a lower R-value (insulating power) than closed-cell spray foam, with a typical spray foam R value per inch that is lower but still effective in the right assemblies

  • Less dense than closed cell spray foam because the cells (bubbles) remain open during application

Closed-cell Spray Foam

  • Higher R-value, making it one of the best insulation for cold climates

  • Expands up to 33 times its size when applied

  • Creates strong air, thermal, and vapor barriers—important when considering a vapor barrier with spray foam cold climate strategy

  • More dense than open-cell spray foam because the cells (bubbles) close when applied

  • More rigid and heavier than open-cell foam, providing structural reinforcement to your home or building during storms

Often selected when determining when to use closed cell spray foam or dialing in proper closed cell spray foam thickness for performance and moisture control, including managing dew point condensation risks

Benefits of Spray Foam

Energy Savings

Spray foam’s air-sealing properties keep conditioned/heated air in, giving your HVAC unit a break by running less often. You’ll enjoy lower heating and cooling costs, improving long-term insulation ROI, and helping answer the question of whether spray foam insulation is worth it for your project.

Improved Indoor Air Quality

Spray foam seals penetration points, preventing pollen and other allergens from leaking into your home or building. It also reduces exposure to outdoor pollutants, a common concern when researching spray foam insulation off-gassing.

High Insulating Power

Both types of spray foam pack a punch with their high R-values per inch, providing excellent thermal resistance, often outperforming traditional options when comparing spray foam vs fiberglass insulation or other materials.

Sound Control

Spray foam seals the penetrations that noise travels through, absorbing sounds and creating a more peaceful environment.

Durability

Spray foam does not shrink, sag, or settle, and sticks to many different materials for the lifetime of your building—helping answer how long does spray foam insulation last and reducing the risk of common spray foam insulation problems when properly installed.

Moisture Control

Closed-cell spray foam does not absorb moisture and helps prevent mold and water damage, making it ideal for unvented attics in cold climate assemblies and high-performance building envelopes.

Spray Foam Insulation Project Gallery

Installer in protective gear spraying closed‑cell foam into a single bay of a post‑frame wall.
Close-up of stud wall packed with spray foam around blue conduit and yellow electrical cables, forming an airtight seal.
Worker finishing a long horizontal strip of spray foam on a post‑frame wall with white wrap backing.
Closed-cell spray foam covers an interior ceiling between red sprinkler lines, lit by a single construction light
Vaulted room with spray-foam base in walls and pink batts in ceiling and gable, windows framed in black.
Expansive vaulted living space with spray foam on walls and ceiling, pink batts in some roof bays, stair opening in floor.
Long interior garage wall insulated with spray foam under open truss ceiling, tools and lumber on slab floor.
White spray-foam covering entire flat ceiling plane between parallel truss chords.
Spray-foam packed wall around a single window opening, with exposed header cavities above.
Partially filled spray-foam wall under vaulted ceiling with visible studs and rough-in wiring.
Large framed room with spray-foam on walls and sloped ceiling trusses, light streaming through plastic-covered window.”
Roof framing with spray foam sealing the left side truss heel while right side remains bare OSB sheathing.
Slanted ceiling fully coated in cream spray foam
Spray-foamed stud wall and ceiling with several window spaces covered by white Tyvek from the exterior.
Vertical view of a high wall section packed with spray foam between studs and a narrow window at top.
Large workshop with car lift, walls and vaulted roof uniformly insulated with spray foam.
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Count on Cullen for Expert Spray Foam Installation

When local homeowners, builders, and contractors need quality insulation solutions, they turn to Cullen Insulation. We’ve been an active part of our community for over three decades and have made a name for ourselves as a company that is committed to excellence in all we do. Our expert team understands our area’s climate and the unique insulation needs of our community—especially when evaluating the best insulation for North Dakota homes, best insulation for Montana winters, and other cold-weather applications.

Spray foam is also a strong solution for specialized structures like metal buildings, shops and garages, pole barns, and insulating a post-frame building, where air sealing and durability are critical.

Our team can also help you understand project-specific considerations, such as spray foam insulation cost per square foot, the total cost to spray foam a house, and potential savings opportunities such as a spray foam insulation tax credit.

Our installation team relies on the durable and dependable products from BASF Spray Polyurethane Foam and Johns Manville for our spray foam projects. Contact us today to learn more about spray foam insulation for your insulation project and receive your free estimate.