If you’ve been researching insulation options for your home, you’ve probably come across spray foam insulation.
But what many homeowners don’t realize right away is that there are two main types of spray foam.
For the purpose of this article, let’s focus on just one of them: open cell spray foam insulation.
So what is open cell spray foam? What is it made of? Where does it work best? And one of the most common questions homeowners ask: is open cell spray foam insulation safe?
Let’s jump right into it.
Key Points: Open Cell Spray Foam Insulation
• Open cell spray foam insulation is a soft, pliable foam that expands to fill gaps and cracks.
• It’s commonly used in attics, crawl spaces, rim joists, wall cavities, and pole barn ceilings.
• Open cell expands nearly 100 times its original size, creating a strong air seal.
• It uses a water-based blowing agent.
• Open cell spray foam helps improve comfort, energy efficiency, and sound dampening.
• The material is flexible, allowing it to move with your home as it settles.
• It’s easier to work with if future wiring or plumbing repairs are needed.
What is Open Cell Spray Foam?
Open cell spray foam is a soft, lightweight, and flexible insulation material.
Unlike traditional insulation materials, which are cut and fitted into place, open cell spray foam is sprayed into cavities, where it expands and conforms to the space.
Because of its expansion and flexibility, open cell spray foam insulation is a great fit for areas like:
- Attics
- Crawl spaces
- Rim joists
- Open wall cavities
- Pole barn ceilings (or walls when drywall will be installed)
Its ability to fill every nook and cranny makes it especially effective at stopping unwanted air movement.
How Does Open Cell Spray Foam Insulation Work?
One of the standout features of open cell spray foam is how much it expands.
Once applied, open cell spray foam expands nearly 100 times its original size. That expansion allows it to fill gaps, cracks, and voids that other insulation materials often miss.
Creating an Air Seal
As the foam expands and cures, it creates a continuous insulation and air seal.
This air seal is key to improving your home’s comfort and energy efficiency.
By reducing air leakage:
- Conditioned air stays inside longer
- Outside air has a harder time getting in
- Your HVAC system doesn’t have to work as hard
The result is more consistent indoor temperatures and less energy loss throughout your building envelope.
Where Open Cell Spray Foam Really Shines
Open cell spray foam has some great benefits, so let’s take a look at what it offers and where.
Attics and Roof Decks
Open cell spray foam is commonly installed in open cavities, specifically the underside of the roof deck in attics.
Here’s a real-world scenario homeowners can appreciate.
If your roof ever develops a leak, open cell spray foam allows water to pass through it. That makes it much easier to quickly identify the source of the leak.
With denser insulation materials, water can travel along hidden paths before becoming visible, making it harder to find and fix.
This scenario also applies to areas of the home, such as the crawl space.
Sound Dampening Benefits
Another often-overlooked benefit of open cell spray foam insulation is its sound-dampening ability.
Because the foam is soft and porous, it helps absorb sound waves. This can reduce noise transfer between rooms and from outside sources, making your home noticeably quieter.
Is Open Cell Spray Foam Insulation Safe?
This is one of the most common questions homeowners ask, and it’s an important one.
When installed properly by trained professionals, open cell spray foam insulation is safe for homes. Once cured, it will stay in place and never need to be replaced.
It’s important to ask your insulation contractor whether the open cell spray foam they use has low VOCs, so you have a better idea of how much it off-gasses. As with any insulation product, safety depends on proper installation, correct application, and adherence to manufacturer guidelines.
Many spray foams are also Class One Fire Rated and don’t act as a catalyst in the event of a fire. This is another thing to ask your contractor about.
What is Open Cell Spray Foam Made Of?
Open cell spray foam is created by mixing two liquid components on-site during installation.
The Two Components Explained
- A-Side: Made up of MDI (methylene diphenyl diisocyanate) blends
- B-Side: Contains polyols, catalysts, surfactants, and a blowing agent
When these two components are combined, they react chemically and expand within seconds to form the foam insulation.
While formulas can vary slightly by manufacturer, the basic chemistry of open cell spray foam insulation remains the same.
Flexibility That Works with Your Home
Homes naturally shift and settle over time.
One of the benefits of open cell spray foam is that it’s pliable, meaning it moves with your home instead of pulling away from framing or cavities.
This flexibility also makes it easier to work with in the future if you need to run electrical wire or repair plumbing. That combination of performance and practicality is why open cell spray foam remains a popular choice for many homeowners.
If you want to learn more about spray foam, injection foam, home insulation, and energy efficiency, be sure to visit our Learning Center. There you’ll find educational articles and videos designed to answer all of your questions.
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FAQs About Open Cell Spray Foam Insulation
What is open cell spray foam insulation used for?
Open cell spray foam insulation is commonly used in attics, crawl spaces, rim joists, open wall cavities, and pole barn ceilings.
It’s ideal for areas where air sealing and sound control are important.
Is open cell spray foam insulation safe for homes?
Yes, when installed correctly by trained professionals, open cell spray foam insulation is safe.
Once cured, it will last the lifetime of the home.
Does open cell spray foam stop air leaks?
Yes.
One of the biggest benefits of open cell spray foam insulation is its ability to create a strong air seal that reduces air leakage throughout the home.
Can open cell spray foam get wet?
Open cell spray foam allows water to pass through it, without retaining the moisture.
This makes open cell a great option for attics, because it can make roof leaks easier to detect rather than trapping the moisture inside the insulation.
Is open cell spray foam easy to work with for future repairs?
Yes.
Because it’s soft and pliable, wires can be easily fished through it. Open cell spray foam can also be cut and removed to gain access to plumbing if repairs are needed.
