Open Cell vs. Closed Cell Foam

In this blog post, we wanted to give a brief “answer” to a frequently asked question: What’s the difference between Open Cell and Closed Cell Foam?

Let it first be said that ANY spray polyurethane foam, when applied correctly, will eliminate drafts, heat loss, and moisture entry, while providing exceptional energy efficiency. Knowing that, the next step is to determine the “best value” solution for the space that needs insulating; a choice between Open Cell and Closed Cell Foam.

Here are a few “fast facts” about each.


  • Is lightweight and pliable
  • Looks “rougher” (less smooth) than Closed Cell Foam because of quick expansion rate
  • Provides R-3.5 per inch
  • Is NOT impenetrable; moisture CAN permeate Open-Cell Foam if exposed
  • Reduces sound transfer; almost twice the sound resistance than Closed Cell
  • Good for filling all “nooks and crannies”
  • BEST used for: attics, vaulted/cathedral ceilings, and walls being covered by a building material.

Some examples of open cell foam:


  • Is rigid and dense
  • Has a higher R-value than Open-Cell; providing an R-6 per inch
  • Provides strength to the structure it is applied to
  • Is more expensive to produce and must be applied in thinner, more accurate “passes” (which increases the cost of installation)
  • Acts as an air AND moisture barrier
  • BEST used for: commercial walls, crawlspaces, and basements; ceiling insulation (can be left exposed and blacked out!); barn/garage insulation; and exterior applications such as air barrier applications.
  • Ask us about our Tank and Duct Insulation Systems!

Some examples of closed cell foam:

Another important thing to note: spray foam that is located in a living/working area MUST be covered by a fire-resistant material. Attics and crawlspaces are typically not subject to this rule as they are not often inhabitated. Examples of thermal barriers include:

  • Drywall and plywood
  • Gypsum board (a drywall material with a fire retardant built in)
  • DC-315 paint that is sprayed directly onto the foam insulation

Applying a thermal barrier can increase the cost of spray foam insulation over other conventional systems.

Spray Foam is the longest lasting, most energy efficient of any insulation product on the market. Whether you choose Open Cell or Closed Cell Foam, the application will last the lifetime of your home, building or barn. Paying a higher cost for a superior product upfront is encouraged as it’s a one-time cost, with lifetime savings and benefits.

This is a great video if you’d like a little more information on the matter.

OR you can give us a call–we’d love to find the best solution for YOUR project! (502) 633-5499

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