Understanding Closed Cell and Open Cell Spray Polyurethane Foam Insulation

There’s no question that spray foam insulation is the best way to go in the Chicagoland area for quality insulation. Spray Foam Insulation (SPF) is commonly used in commercial and residential structures because of its abilities to completely seal a space and provide adequate insulation. This can be especially important for attics where poor insulation has been detected during winter months where warm air may be leaking out and summer months where cool air is escaping.  Simply stated, spray foam keeps your home warm in the winter and cool during the summer.

There are two common types of SPF on the market. Those two types of SPF are Closed Cell SPF and Open Cell SPF.


What is the Difference between Closed Cell and Open Cell Spray Polyurethane Foam Insulation?

Open cell spray foam has an open cell structure in which its cells that basically fill the air, thus the name open cell spray foam. With open cell foam, the bubbles within the insulation share walls with one another. Open Cell Foam is deemed to be a lightweight insulation that weights approximately ½ pound per cubic foot. The material itself as a result is softer and more flexible. Whereas closed cell has cells that are dependent on one another instead of the walls and more than 90% of those cells are closed. They produce a more rigid, harder product. 

Open and closed cell spray foams actually look a lot alike and can be difficult to differentiate between visually. Both types of SPF are available in a variety of colors, however, you can squeeze the spray foam for a closer inspection. Closed cell spray foam will always be the more difficult product to squeeze or crush. In fact, there are some closed cell spray foams on which you can stand. Whereas, open cell spray foam has a consistency that rivals angel food cake. 

Both types of SPF are rated as excellent insulation materials but in the Chicagoland area, Closed Cell SPF is the foam of choice because of its weight and overall strength!


More about Closed Cell Spray Polyurethane Foam Insulation

Closed cell spray polyurethane foam is the spray foam of choice because it has a more consistent past performance than open cell spray. Closed cell spray foam is stronger than open cell spray because of its higher compressive qualities and according to studies has the power to increase racking strength of walls by as much as 300%. It’s great overall simply because it does not absorb water. It is particularly great for the top of roof decks of flat roof commercial buildings because of it does not absorb very much water if any nor does moisture vapor slip through it.  

Speaking of moisture, closed cell SPF has the highest R-value. Closed cell polyurethane foams have higher R-values(resistance-to-heat-loss) than other types of foam, around 6.0 per inch, although some stronger ones have R-values of 7.14 per inch and higher. It is highly water-resistant and most importantly, it does not hold water either. This is particularly important in keeping humidity low, reducing leaks and regulating temperature. 

Closed Cell SPF also seals to reduce overall air infiltration but also keeps air from seeping out which is important for basements, attics and crawlspaces during winter and summer months. This quality can prove to be very beneficial for energy costs throughout the various seasons helping to keep costs lower than they might be.  Closed cell spray foam is a highly favored product for those spaces that are most difficult to insulate such as rooms or apartments over the garage. 

Closed cell spray is more expensive than open cell spray over the short term but over the long term, it pays for itself in savings. 


About Open Cell Spray Foam Insulation

Many find open cell spray foam to be an attractive option because it is cheaper than closed cell spray foams and outperforms fiber glass insulation. It is recommended for walls, floors, unvented and vented attics and ceilings, providing insulation for cavities of any shape and creating a "seamless" protective air barrier that minimizes or eliminates air leakage for maximum building envelope performance.

Open cell spray foam expands once applied making it to be another product that is great for use in hard to reach spaces for insulation such as wall and ceiling nooks and cavities. The R-value of open cell polyurethane spray foam is lower, in the 3.6 to 3.8 per inch range. What’s the significance of a lower R-value? This means that the structure is at an increased risk for poor insulation performance in the face of extreme temperatures or climates. It is also more vulnerable to moisture, which creates risk for bacteria and mold which can ultimately damage the wood and overall structure. It is also more permeable to vapor, air and noise frequency. Simply stated, it does not provide the same support to walls as closed cell spray foam. 


In summary, closed cell spray foam is the best way to go when insulating your attic, basement or crawlspace in the Chicagoland area. Though it is a bit costlier up front, the long term benefits and savings are worth the expense.