As you research spray foam insulation, you’ll likely come across the terms “open cell” and “closed cell.” These are different types of spray foam insulation that can both serve as effective solutions depending on climate or areas of the home or building project.
Below is a description of the similarities and differences between open cell and closed cell spray foam insulation.
Both types of spray foam insulation share the following:
- Provide you an air barrier, for an air tight wall system.
- Neither foam provides a “food source” for mold or pests.
- Fills every crack and crevice.
- Sticks to most substrates.
- More energy efficient compared to traditional insulation types.
While the two types of insulation do share similarities, their differences are significant.
Closed cell spray foam is much more dense than open cell, because, as the name implies, the small gas bubbles (cells) within the insulation are fully closed. Since there are no openings in closed cell foam, the insulation does not absorb water and effectively retards the passage of water vapor.
Additionally, closed cell foam is much more rigid adding structural support as a bonus in the locations it is sprayed. In general, closed cell spray foam costs more, as it expands less than open cell foam upon application and requires more material. This being said, closed cell costs more per R-value.
Use closed cell foam where you need a more rigid final surface or in high humidity environments.
Open cell is a more cost effective product to use in exterior wall applications where it will be out of the weather.
In open cell spray foam, the tiny bubbles (cells) within the foam are not completely closed and are connected by tiny air pockets. Because of this, open cell foam has a soft, “spongy” texture and is less rigid than closed cell foam.
Open cell foams are more effective in sound proofing characteristics.
Which Foam Is Better?
Unfortunately for those who like objective answers, there isn’t one in this case. Both open call and closed cell foams have their individual strengths. Closed cell foam, for example, is used for areas where moisture is an issue or where a more rigid foam would be better, such as on outside structures.
It is always better to use a contractor that has many years of experience to give you the best advice for your project and which foam material to use. We highly recommend having this discussion up-front with your contractor, before the job starts, so you get the most appropriate and cost-effective solution.