Open cell vs closed-cell spray foam

Open cell vs closed-cell spray foam

Spray foam insulation is the best way to make sure your house is as energy efficient as possible while also being extremely comfortable to live in. It also increases the value of your home in case you decide to sell it.

But, since there are two types of spray foam insulation, open-cell, and closed-cell, the online forums have been engaged in a long-standing debate of Open cell vs closed-cell spray foam. 

While open-cell spray foams have cells that have more space in them, closed-cell spray foam cells are more compact, hence giving the spray foams their respective names. They have different densities, have different costs, expand differently upon application, and have different R-values. This is why you have to be careful when choosing one between them. 

Let’s take a look at various aspects of open-cell and closed-cell spray foam. 

Which one should I choose between open cell and closed-cell spray foam?

As spray foam insulation is gradually replacing other traditional methods of insulation such as fiberglass, people are getting more and more invested in the ins and outs of this insulation.

open cell vs closed cell spray foam

And since there are two different types of spray foam, it is only natural for people to become confused while choosing them, especially if they don’t know all the details about them. 

Let’s check out both open-cell spray foam and closed-cell spray foam to help you decide between them. 

What is open cell insulation?

Open cell spray foams are lighter spray foams that have a lot of open spaces within their cells.

These spaces are filled with air, which makes them less dense and flexible. Other than their cell composition, there are plenty of other traits that set them apart. 

1. Cell density

The cell density of open cell insulation is quite low. This is due to them having a lot of spaces in their cells that are full of air. As a result, their mass per unit volume is much lower than closed-cell insulation. 

2. Expansion

Open foam insulation expands very quickly when it is applied on a surface. As soon as they are applied, they keep spreading to fill every nook and cranny of the surface they are applied on.

This insulation can expand more than 100 times its original volume, and hence, can cover a lot of areas. This is because the open cell insulation is very light and the air inside the cells of the foam allows it to expand fast and over large areas. 

3. Cost

open cell spray foam insulation cost

The cost of applying open-cell spray foam is quite low when compared to its counterpart. Since they expand quite fast and over a larger area, the amount in which they have to be applied isn’t very high.

Since they can be sprayed in smaller amounts, the labor cost is less than that of closed-cell insulation. 

4. Sound dampening

One of the best aspects of open-cell insulation is that they work as better sound dampeners than closed-cell ones.

This is because of the presence of air in their cells. They won’t soundproof your home, but they will reduce the intensity of the sound entering your home by a large margin. 

5. Water absorption

Open cell spray foams absorb and retain a lot of water, which can be a downside to installing them in your homes. Because they retain so much water, the risk of water damage and mold growth goes up significantly. 

But there is an advantage to having open cell spray foam insulation on the roofs, as they can change color when the amount of absorbed water is too high. This can alert the homeowner and they can replace the insulation. 

6. R-value

The R-value of insulation indicates the heat resistance power of that insulation. The higher the R-value is, the higher the heat-blocking capacity of that insulation is.

Open-cell insulations have a lower R-value, which is around 3.5 to 4 per inch sprayed. So, the energy efficiency of a house goes down if you install open-cell insulation. 

What is closed-cell insulation?

Closed cell insulation is a type of insulation where the cells have no space in them, creating dense and compact spray foam insulation. They are more rigid than their open-cell counterparts.

Let’s take a look at various traits of this insulation to see what makes them desirable.

1. Density

Closed-cell insulation is very dense due to them not having any space in their cells. This is why they are much heavier than open-cell spray foam insulation as well. 

2. Expansion

Due to closed-cell spray foam not having any air in its cells, they don’t expand very much upon application. When they are applied on a surface, they only expand only 33 times their original volume.

This causes more closed-cell insulation to be applied to fill out the same area as the open-cell insulation. 

3. Cost

spray foam insulation cost

Since you need to apply more spray foam on a surface to cover a small area, the cost of closed-cell spray foam insulation is much more than that of an open-cell one.

Both the labor cost and the cost of closed-cell insulation are higher than that of open-cell insulation. 

For in detail cost assumption you can read this article “How much does spray foam insulation cost

4. R-value

Compared to open-cell insulation, closed-cell insulation has a much higher R-value. This means the closed-cell spray foam has a much greater capacity of blocking out heat. As a result, during summer, cooler air inside the home doesn’t go out of the house, while the hot air outside can’t come into the house. 

This is made possible due to the insulation not having any space in them through which air can come in. As a result, the energy efficiency of a house having closed-cell spray foam insulation is much greater than a house with open-cell insulation. 

5. Rigidity

Closed-cell insulation is not nearly as flexible as open-cell insulation. As a result, they are rigid and provided much-needed structural support to the home they are installed in. As a result, you won’t have to worry about your walls, roofs, etc cracking. 

6. Water absorption

Unlike open-cell insulation, closed-cell spray foam neither absorbs nor retains water. As a result, there is almost no chance of water damage or mold growth on the walls. 

7. Sound dampening

If you want to reduce noise entering your home, then you should stay away from closed-cell insulation. Due to the insulation not having air in it, it can’t dampen noise like open-cell insulation. 

Final Words

If there is anything we have learned from the comparative analysis of open-cell vs closed-cell spray foam is that there is no clear winner in this debate.

The insulation you should choose should be decided based on what you want from your insulation. 


1. What is 2 closed cell foam insulation?

2 closed cell foam insulation is a type of spray foam insulation that has weights of 1.5 to 2 pounds. They are sprayed as a liquid and can expand up to 50 times their volume as a liquid. 

2. Where is open cell spray foam used?

Open-cell spray foam is used in places such as crawl spaces, rim joists, open wall cavities, and of course, attics. 

3. Is open cell foam worth it?

Whether any spray foam, open cell or closed-cell foam is worth it depends on what you expect from your insulation. If you want a cheaper alternative to closed-cell insulation which also covers a large area and dampens sound, then open-cell foam is worth it.