Different Types of Spray Foam: Qualities and Specs

Have you finally decided to insulate your home with spray foam? Most likely you’re here because you cannot tell the difference between the two types of spray foam and which one works best where. You’re in the right place! Read on to learn more. 

Since the 1940s, spray foam was used in aircrafts but in the recent past, people have adopted its use in home construction. Spray foam has good qualities that make it stand tall against other types of insulation. There are two main types of spray foam insulation as shown below. 

  1. Open cell spray foam 
  2. Closed cell spray foam 

Let’s have a look at each of the two types of spray foam. 

Open cell Spray Foam 

Open cell spray foam is made of a polyisocyanurate also known as an ISO and a resin. The two compounds come separately and are only mixed when applying on a surface. Most manufacturers will label the chemicals as A and B. A is usually the ISO that will remain the same across many brands. However, the resin may vary because it comprises the blowing agent, fire retardant, polyol, and surfactants. 

Open cell spray foam works best when used on exposed walls, pole barn insulation, attic areas, rim joists, and crawl spaces. The R-value of open cell foam ranges from 3.6 to 3.8 per inch thereby giving it thermal resistance. The effectiveness of any insulation is measured using the R-value which determines how well insulation is able to resist heat gain and heat loss. 

Benefits of Open Cell Spray Foam 

If you’re wondering why you should use open cell spray and not any other for your insulation needs, here are some of the benefits you’ll get.

• Cheaper than closed cell 

Open cell foam is cheaper than closed cell foam but still gives the same benefits. If you’re limited on budget, this is your go to method of insulation. 

• Great for soundproofing 

Do you live in a noisy area and you’re looking for a way to dampen the noise? Look no further because open cell spray foam can offer that and much more. 

• Water impermeable 

Spray foam has some ability to prevent water leakages but isn’t entirely impermeable. Although the insulation allows water and vapor to infiltrate, it doesn’t retain the water. Another great quality is that even with some level of water permeability, open cell spray foam doesn’t lose its insulation properties. 

• Mold resistant 

Open cell foam is ideal because it doesn’t permit growth of mold and mildew. This is because the insulation doesn’t retain water in between the cells. 

• Pest Resistant 

Another great advantage of using open cell foam is that it fills all gaps leaving no spaces. Pests such as insects or rodents therefore have no entry point into a building. 

• Energy efficiency 

Open cell spray foam makes your home more comfortable by giving it warmth in winter and keeping it cool in summer. The fact that a home can resist heat loss or heat gain also saves the homeowner on money that would have otherwise been used to cater for energy bills and air conditioning. 

Closed Cell Spray Foam 

Unlike open cell spray foam, the closed cell foam is denser and forms a rigid layer upon curing on a surface. The cells on the foam are closed rather than open making it an effective insulation, water barrier, and air barrier. 

Closed cell foam is made of an ISO and a resin just like open cell foam. The product comes in two containers labeled A and B and are only mixed on the site. Upon installation, closed cell foam expands to 100 times its original volume filling all crevices. 

You can use closed cell spray foam for exposed walls in a pole barn, walls in a home or residential building, closed cell foam also works perfectly in the attic, floors, and ceilings. 

The R-value of closed cell foam ranges between 6.5 to 7 per inch. Compared to other forms of insulation, closed cell foam is the best if you’re looking for efficient thermal resistance. The R-value measures the ability of insulation to resist heat gain and heat loss. 

Benefits of Closed Cell Spray Foam 

Here are some of the benefits to expect if you decide to use closed cell spray foam insulation. 

• Air sealing 

Closed cell foam forms the perfect air seal on surfaces. As noted above, the insulation has closed cells that don’t allow any air to infiltrate through a surface. If you’re struggling with drafts and cold air infiltrating into your home, closed cell foam is the best solution. 

• Water impermeable 

Unlike open cell spray foam, closed cell foam fills all cavities preventing any moisture or water to leak through. 

• Strengthens the structure 

Closed cell foam forms a rigid layer on surfaces making the structures stronger. In areas prone to strong winds, the building codes require builders to use closed cell foam to strengthen the structures. 

• Prevents dust and pollen 

By filling in all air spaces around surfaces, closed spray foam prevents dust and pollen from penetrating into a building. We all know how annoying dust and pollen can be especially for people who have respiratory problems. 

• Protects against pests 

Pests such as rodents, ants, and other bugs can be a nuisance. The pests are attracted to homes or buildings where they can find food. Insulating the cavities in such buildings using closed cell foam can keep pests away because the insulation doesn’t leave any spaces where pests can crawl. 


Spray foam is among the best methods of insulation. It comes either as closed cell foam or open cell foam. The two types are almost similar in performance but the closed cell is denser and forms a more rigid layer of insulation. Open cell is light and it becomes soggy over time because it’s not entirely water impermeable.