Though spray foam insulation has been in use since the 1940s, mostly for aircraft, for the past 30 years, continual product innovation has seen the increased adoption of spray foam insulation in residential and commercial construction. The rapid growth of sprayed foam insulation in building construction, thanks in part to its instant and long-term advantages, has allowed the insulation material to sit confidently alongside traditional insulation types in offering thermal comfort for building occupants.

But what is spray foam insulation? Are there different kinds available for various applications? How does sprayed foam insulation address the latest building codes while anticipating any changes to the structure code? In this article, we explore the fundamentals of insulating foam and more.

What Is Spray Foam Insulation?

What is Spray Foam Insulation

Spray foam insulation is a two-part liquid insulation material that insulates and air seals where it is applied.

Spray foam insulation also called foaming insulation or sprayed insulation, is a two-part liquid insulation material that insulates and air seals where it is applied. It comes in two large 55-gallon drums – an iso and a resin. These two liquids are kept separate until applied at the job site by a competent, licensed spray foam installer. The two liquids travel up through a heated tube to the spray gun, where they are combined to create the foam. The foam expands within seconds to fill the cavity surface. Depending on the form of sprayed-in foam insulation used, closed-cell or open-cell, the foam expands between 40 and 100 times its size upon application.

Types of Spray Foam Insulation

Product innovation over the years has seen the introduction of numerous different types of spray foam insulation. Mostly in residential and commercial construction, open-cell and closed-cell spray foam are used while high-density spray insulation is utilized as roofing foam in a commercial or industrial building. Open-cell sprayed-in foam insulation, a soft low-density material, is usually used for interior applications such as wall cavities, the underside of roof decks, attics, basement walls, and crawlspaces. The open cell structure of low-density foamed insulation permits moisture permeability to help contribute to the moisture management and bi-directional drying of the wall assembly.

Closed-cell spray insulation, a rigid medium-density material, can be used in exterior applications like continuous insulation applications, and interior applications. This form of foam insulation has a higher R-value per inch, making it also suitable for small areas that need the highest possible R-value to meet building code requirements. Closed-cell spray foam’s rigidity help reject bulk water, making it a known flood-resistant material by FEMA.

The Advantages of Open-Cell Spray Foam

As mentioned, open-cell foaming insulation is best suited for interior applications, providing an array of advantages of traditional fibrous insulation materials. Advantages of open-cell foam insulation include:

  • Offers sound dampening qualities, ideal for use media or theater rooms
  • Lower installed price, per square foot
  • Is not regarded as a food source for mold
  • Can be installed at a significantly lower price and target the same specified R-value
  • Can house long-term creep and seasonal movement
  • Permits for bi-directional drying

The Benefits of Closed-Cell Insulation Foam

How Thick Does Spray Foam Insulation Need to Be

Benefits of closed-cell insulation foam include ability to reject bulk water.

While open-cell foamed insulation has many benefits over traditional insulation kinds, closed-cell sprayed-in insulation goes beyond to offer extra advantages. Though closed-cell spray insulation foam has a higher per board foot cost, there are benefits that the material offers as well as:

  • Ability to reject bulk water
  • Can be applied at extremely low temperatures (as low as 5°F)
  • Adds wall racking strength and impact resistance
  • Higher R-value per inch-easier to accommodate high R-value requirements in thin spaces
  • Lower vapor permeance (can be a Class II VDR)
  • Higher tensile and bond strength

How Does Spray Foam Insulation R-Value Compare?

R-value, the thermal resistance measure of insulation, differs between all insulation products, whether they are fiberglass, cellulose, open-cell spray foam insulation, or closed-cell sprayed-in foam insulation. Typically speaking, the rule of thumb is the higher the R-value, the greater the insulating power. Focusing on spray foam insulation materials, there is a difference between the two main types. According to an industry publication, Fine HomeBuilding, the R-value for open-cell spray foam is between R-3.5 – R-3.6 per inch. Nevertheless, there are open-cell spray foam insulation products that actually offer R-3.7 per inch like Icynene Classic and Icynene Classic Max. The open cell structure of low-density foam insulation means the R-value is lower than its closed-cell counterpart. However, open-cell spray foam does offer superior and consistent thermal insulation and air sealing properties.

Concerning closed-cell sprayed in foam insulation, R-value can range between R-4.9 to R-7.1 per inch. Closed-cell insulation products, like Icynene ProSeal, allow builders and architects the ability to achieve R-21 in a three-inch pass. Innovations like the Icynene ProSeal LE allow for an initial pass of five inches (5”) to achieve R-35.

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