Why Do People Say Closed Cell Spray Foam is Better Than Open Cell?
This might be true for some projects, but definitely not all.
RetroFoam of Michigan has been installing spray foam insulation, both open cell and closed cell, for more than 10 years. Our crews are specially trained by our spray foam manufacturer to ensure each project is installed flawlessly.
Our estimators also have the experience and the wherewithal to know whether closed cell or open cell spray foam will be the best fit for your project.
Enough about us, let’s talk about you or more importantly clearing up the misconception that closed cell is always the best option. Now let’s dive in and discuss what closed cell is and why people believe closed cell is the best.
Closed Cell vs Open Cell
Both closed cell and open cell create an air seal but have very different compositions, expansion rates, moisture permeability, and sound deadening qualities.
Let’s take a quick look.
Closed cell is a very rigid material, making it ideal for structures that will have the walls exposed because it is so durable. Open cell is better for a structure where the drywall will be put up after the installation or in an area where it isn’t going to get knocked into frequently.
What makes closed cell so great for cargo vans is that it has a minimal expansion rate. On the other hand, open cell is great for homes because the expansion rate is so high it fills all of the nooks and crannies where it is applied.
Open cell spray foam is inherently moisture permeable, which means water can move through it. This is actually a good thing if your home were to spring a leak, so you’d be able to find it. Closed cell is 100 percent moisture impermeable, so, you guessed it -- water can’t move through it. This means if there is a leak, the closed cell will conceal it until the water builds up, causing a much larger problem.
Another thing you might be worried about is sound dampening, whether it’s in your home or your pole barn. The thicker, softer consistency of open cell works to reduce sound coming into your home or out of your workshop. The tight, dense closed cell doesn’t have those same capabilities.
Why People Think Closed Cell Spray Foam is the Best
One of the main reasons people think closed cell spray foam is better than open cell is because it has a higher R-Value per inch.
The thing is though if that’s what you’re basing your decision on then you’re already starting off on the wrong foot. R-Value doesn’t tell the whole story when you’re considering spray foam insulation for your home. That’s because R-Value isn’t as big of a piece of the puzzle as creating an air seal.
Now, another thing people say is that the rigidity of closed cell spray foam will add structural integrity to the building. That’s not really as true as people think it is. If you’re counting on insulation to strengthen your building you have other problems you need to deal with.
This rigidity of closed cell spray foam makes it perfect for a workshop, but it can be harmful down the road in a home, especially if there is a leak in the roof or the electrical or plumbing needs to be changed. Essentially you would need to bring in power tools to cut out sections to replace the plumbing or wiring. Closed cell will also hide those leaks coming from the roof, so while you cut a section out, it could be coming from another area entirely.
Now we’re not saying closed cell spray foam is bad. It actually creates a strong bond on the roof deck of pole barns and can help keep water from leaking through the weak spots if they were to pop up. It also is durable enough to handle the abuse of tools banging against it and anything you can throw at it.
This rigidity though isn’t ideal for a new build home. After a home is built it is going to shift and settle. Closed cell won’t shift with the house, which means it has the potential to separate from where it was applied. This can lead to air leakage throughout the home.
There is one final reason why people think closed cell is the best option for their home insulation – word of mouth.
There is a decent amount of contractors who push closed cell like the gospel of insulation. While they sing its praises, their motives aren’t as genuine in some cases. Some contractors push it because they don’t know much about open cell, but others push it because closed cell costs more or that is the only type of spray foam they install.
Closed cell spray foam insulation is a great insulator for certain projects, just not for everything under the sun. The great thing is, open cell is also a great insulation material and can get the job done in spaces where closed cell isn’t the best fit.
Choosing the Best Spray Foam for Your Project
At the end of the day, both open and closed cell spray foam work well, but the best one for your project will depend on your specific situation and application.
If you’re looking to expand your knowledge even further on everything spray foam, check out the Learning Center on our website. You’ll find a ton of resources that will help you determine which foam insulation will be best for your project.
About Amanda Ringler
Amanda previously has worked as a breaking news and crime reporter, TV news producer, and editor in Flint and Detroit. Throughout her career as a journalist, she has won several awards from the The Society of Professional Journalists - Detroit Chapter and the Michigan Press Association. As part of the RetroFoam of Michigan family, Amanda uses her experience as a journalist to write content that will help educate homeowners on the benefits of foam insulation. When Amanda isn’t writing, she’s spending time with her husband and rescued huskies. She also loves knitting, making art, cooking, and hosting dinner and a movie night for friends and family.