Insulation Spray FoamPerson in blue suit spraying foam insulation on wooden walls.

Spray foam insulation has long outperformed cellulose, and fiberglass. Due to its high expansion rate and spray application, it is able to create a better air seal and has a higher R-value which combined lead to less energy loss. With this in mind it’s not shocking that spray foam insulation has become a common product among home contractors. As new environmentally friendly options continue to hit the market in the wake of HFC bans by The Clean Air Act, spray foam popularity is seeing even more growth. From commercial use to residential, there are two main options to choose from, open cell and closed cell foam.

What’s the Difference Between Open Cell and Closed Cell Spray Foam? 

The primary difference derives from their names with open cells being made up of cells with small air pockets, and closed cells being densely packed cells that are airtight. This structure forms the basis for the main separations between the two, and allows each to perform better at certain jobs. Here are the main differences:


With the absence of air, closed cell spray foam is much more densely packed causing it to be 3-4 times heavier than open cell spray foam. 


Thanks to the air pockets in its cell structure, open cell spray foam is very flexible compared to the rigid makeup of closed cell foam. 


Open cell foam will expand 4x more than closed cell foam. This means less open cell foam is needed to fill the same space as closed cell foam. 

R Value

Closed cell foam has a higher R value than open cell foam. With closed cell foam you can expect around an RF7 vs RF4. 

It is important to note that though R value plays a large role in keeping a space insulated, a bigger factor is seal. Having a clean seal will go further than more RF factor and ratings are based on proper application. You can’t simply rely on a higher RF factor for energy savings. 


Open cell is much more cost effective due to its high expansion rate. Less foam is needed to fill the same volume of space, and therefore the cost is less. 


Closed cell foam retains its shape much better than open cell foam and because of this, lasts longer on average. 

That being said, no matter which you use, both will last a lifetime with a 90 year rating on average. 


Though quality plays a big factor and some open cell foams only have a permeability of 5% their weight in water, this points out that open cell foams are not waterproof. Closed cell foams on the other hand are completely impermeable. 

Sound Dampening

Open cell foam is great at reducing sound transmission whereas closed cell foam is not as effective. 

When to Use Open Vs Closed Cell Spray Foam

After looking at the many differences it’s clear that each foam has pluses and minuses. With that in mind, here’s when to use each:

Open Cell Spray Foam

  • Residential property 
  • Hard to reach areas and those that require high expansion rate to fill all the nooks and crannies 
  • When cost is a major factor
  • Roof deck – open cell can help identify leaks because water can pass through exactly where the leak is, changing color and alerting you to the problem
  • In spaces where you may need to access wiring in the future: closed cell is very hard to work with once set and requires power tools to penetrate and access the cavity
  • In areas where sound dampening is desired

Closed Cell Spray Foam

  • Commercial property and exterior areas
  • When higher RF value is desired
  • In spaces where extra structural support would be beneficial
  • For projects seeking ultimate longevity 

Empire Foam Can Help With Your Decision

With over 15 years crafting custom foam products for contractors, Empire Foam is a leader in the space. Our portable low pressure spray foam machine has aided small contractors by providing world class performance at a much lower entry point. Whatever your needs we are able to make open cell and closed cell spray foam products to make your project a success. To get started, give us a call: 518-587-0285 or contact us.