What are the differences between open cell and closed cell spray foam insulation?


Spray foam (SPF) insulation is a liquid sprayed into areas before expanding to cover cracks and crevices, creating a seamless, airtight seal. Open-cell and closed-cell spray foam insulation are the two most common varieties. This article extensively analyzes the differences between open-cell (ocSPF) and closed-cell SPF (ccSPF) insulation.

What is open-cell SPF insulation?

Insulation made from open-cell spray foam (ocSPF) has a honeycomb-like structure and is filled with air. With a density of only 0.5-0.8 pcf, ocSPF is a lightweight, malleable foam. Like fiberglass and cellulose, the air remains the principal insulating medium in ocSPF. Typically, open-cell foam has an R-value per inch between R3.6 and R4.5.

Depending on its thickness, ocSPF can function as an air-barrier material that prevents air from escaping the structure. Since ocSPF absorbs some water vapor which acts as a retarder and may be necessary for cooler climates.

What is closed-cell SPF insulation?

The closed cell structure of closed-cell spray foam insulation results in a dense, rigid foam with a density of 1.8 to 2.3 pounds per cubic foot. The R-value is increased because the blowing agent used in ccSPF is less thermally conductive than air. Applications with restricted space can benefit from closed-cell foam because of its high R-value per inch (often R5.8 to R6.9*).

Similarly to ocSPF, ccSPF can act as an air-barrier material when it is thick enough. Because of its closed-cell structure, ccSPF is the only spray foam suitable for use in environments where it is likely to come into contact with water (e.g., below-grade concrete walls, in connection with the ground, or on the exterior side of the building envelope).

ccSPF does not need an extra vapor retarder in most situations because it has a moisture permeance of fewer than 1.0 perms at a thickness of 1.5 inches. The Federal Emergency Management Agency (FEMA) recognizes ccSPFs for their resistance to water absorption and as a flood-resistant material, and is possible that a vapor retarder installation is needed in colder climates.

Comparison of open-cell and closed-cell SPF insulation

The former often has a higher R-value per inch when comparing open-cell with closed-cell foam. Typically, the closed-cell foam will cost you more than its open-cell counterpart.

Versatility and simple set-up: When compared to closed-cell foam, open-cell foam is more comfortable to work with and has greater flexibility, which might make it more manageable throughout the installation process.

Anti-microbial and airtight properties: Unlike open-cell foam, closed-cell foam is more resistant to moisture absorption and creates a more airtight seal. Open-cell and closed-cell foam are good at absorbing sound, but closed-cell foam may be more effective because of its increased density.

Factors to consider when choosing between open-cell and closed-cell SPF insulation

Closed-cell foam may be the best option if you need to meet strict R-value specifications. If cost is an issue, you should know that closed-cell foam is typically more expensive than open-cell foam.

Location and purpose should be determined first at which point you may choose between open-cell and closed-cell foam depending on where and how the insulation will be used.

Closed-cell foam, for instance, is more weather- and moisture-resistant, making it a better choice for outdoor and underground use. The local climate and temperature may also play a role in your decision-making process.

Closed-cell foam, for instance, may be preferable in colder locations because of its higher R-value and moisture resistance. The SPF insulation you install must abide by all applicable regional, state, and federal construction codes. Regulations for specific uses may mandate specific forms of SPF insulation.

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