Spray Foam Insulation: Open Cell vs Closed Cell
Spray polyurethane foam (SPF) is the best way to stop air leakage when it comes to
insulation. Today it is more important to stop air leaks and conserve energy than any other time
in history. We have to pay more for energy each and every year that passes by. It doesn’t matter
if we are constructing a new home or remodeling and upgrading the one we live in SPF is the
best option available to us for saving energy and stopping air leaks. Spray foam insulation is
available in open cell and closed cell foam. We will look at both types and explain the
differences in both.
In closed cell foam gas is trapped inside the bubbles when this foam is cured. This
trapped gas that fill the bubbles gives this foam the great insulating capacity that it has. This is
the denser of the two types of foams. The density of this foam gives it the higher R-value. A
closed cell foam has an R-value of 6.6 per inch. The density also gives it more strength and
makes it a good moisture and vapor barrier. It I used a lot on the bottoms of roofs to help block
the heat and add strength.
Open cell does not have the strength that closed cell does. The R-value is about 3.8 per
inch in this less dense foam. Also this foam is more porous and the holes are not filled with
gases. The strength isn’t there like closed cell and it does let moisture pass through. It is like
comparing an open window to a closed window. This foam may be less expensive but it will take
more to reach the R-value found in the closed cell.
Open-cell SPF physical properties:
Softer and spongier Will typically fill stud cavities well
Will be shaved flush with the studs after installation
Gives you a smooth finish
Usually white or light yellow in color
Closed-cell SPF physical properties:
Firm to the touch
Will usually not fill stud cavity after foam is sprayed
Comes in a variety of colors such as green, purple, dark yellow, light yellow, and
When you use SPF regardless of open or closed when you spray the foam on your walls
prior to installing your sheet rock all of your cavities behind electrical wires, plumping pipes, and
behind all of your electrical outlet boxes and switch boxes are filled with foam. You have a more
consistent filling of these gaps which are places where a lot of air leakage occurs. When you use
SPF in your attics you also have a more consistent coverage and also a more airtight seal. In your
attic you have an abundance of places where you can and will have air leaks. If you do not know
it while your a/c unit is running downstairs it is pulling hot air from your attic through these
leaks around your light fixtures and other places air leakages occur in your attic. SPF is an
excellent choice to help solve this huge problem and bring down your energy bills.
To really make the determination on which foam would be best for your application you
really need to consult your local SPF contractor and make an appointment with him to make the decision on which is the best for you. This is a great option that really will save you money and
save energy for a lone time to come.