Everything You Need to Know About Exterior Foam Insulation

If you’re looking to make improvements to your home, exterior foam insulation is something that you’ll want to seriously consider. Exterior foam insulation has been growing in popularity over the years. They can be used to insulate everything from basements, rim joints, and other difficult-to-reach locations. Now, some of you may still be on the fence about this as you may not know much about exterior foam insulation.  If you’re considering installing exterior foam insulation but need to know more about it, then we’ve got just the thing for you. Here’s everything that you need to know about exterior foam insulation.

What Is Exterior Foam Insulation?

Exterior foam board insulation is the most common type of insulation used on homes. A layer of XPS or Polyiso foam board is installed on top of the wall sheathing, followed by a layer of house wrap. The seams are then taped with an approved foam insulation tape. 

What Are the Advantages of Exterior Foam Insulation?

There are a slew of advantages that come with utilizing exterior foam insulation. Here are some notable benefits to keep in mind:

  • A continuous layer of insulation is much better than just insulating the stud cavities. This is because thermal bridging is reduced when there is only cavity insulation. This results in a higher effective R-value.
  • Properly installing a continuous layer of foam board and sealing the seams can significantly reduce air infiltration and drafts. Reducing air infiltration can greatly improve the effective R-value of insulation materials like fibreglass.
  • Lastly, exterior foam insulation allows for a thinner wall profile. This can be a difference-maker if you need to make the walls thin without having to sacrifice functionality.

What Are the Drawbacks of Exterior Foam Insulation?

While exterior foam insulation can be quite useful, there are some things that you need to consider before opting for this option. Here are a few drawbacks to consider when it comes to exterior foam insulation:

  • Exterior foam insulation tends to cost more than internal wall insulation options. They also take more time to install.
  • Exterior foam insulation can be susceptible to sunlight. UV rays can damage the material so you need to make sure that it’s installed properly.
  • They also need to be fitted correctly. Failing to do so will leave room for air infiltration.
  • The air bubbles inside the expanded polystyrene board (EPS or beadboard) prevent heat transfer, but they can also collect moisture. This can make the board ineffective, so you may need to put a moisture barrier in place, depending on where you’re installing it.


We hope this article proves to be useful when it comes to helping you gain a better understanding of exterior foam insulation. As you can see, exterior foam insulation can be great as long as it is installed and fitted properly. While exterior foam insulation does come with some drawbacks, the advantages pretty much offset any disadvantages that come with them. Be sure to keep everything you’ve learned here in mind so that you can make the most informed decisions for your home.

Foamworks is a leading insulation contractor specializing in the quality application of spray foam insulation. Spray foam is widely recognized as the first choice insulation option for home and commercial projects. For more information, visit our website today!

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