Spray-On Insulation: Open-Cell and Closed-Cell Insulation Foams
Commercial building structures often require insulation to perform in a successful way. There are several types of insulation, but spray-on foam insulation is one of the most common used types. Either a 0.5 lb./cu. ft., open cell foam, or 2.0 lb./cu. ft. closed cell foam insulation, you must decide and this will have a big impact in cost, application methods, and performance.
There are two major factors to understand and consider if you are using these two alternatives. The first is the nature of the foam.
It is either open-cell foam, where the tiny cells of the insulation foam are not completely closed, and air fills all the 'open' space inside the material. This will allow having weaker foam or a softer feeling. Using the closed-cell foam, tiny cells are closed and filled with a gas that helps the foam rise and expands and become a greater insulator. The most common properties obtained from these cells are their size and density.
Spray-On Insulation: Density of Materials
This measurement is calculated weighing one solid cubic foot of foam material. Open cell foam insulation typically weighs in at 0.4 to 0.5 lb./cu. ft. Closed cell foam for insulation applications ranges in density from 1.7 lb./cu. ft. to 2.0 lb./cu. ft. Roofing applications typically use a 2.8 to 3.0+ lb./cu. ft. to support traffic and loads better. Having a higher density in the material, will provide better insulation properties, because it signifies that the voids are filled, and the structure is packed all together. Lighter polyurethane foams are molded into decorative interior molding and painted or stained for a simulated wood effect. These “higher density” foams are typically in the 30 lb./cu. ft. to 40 lb./cu. ft. density range.
In the U.S., insulation is measured in "R-Value" (R= resistance to heat flow), and closed-cell polyurethane spray foam insulation has among the highest R-Values of any commercially available insulation.
Benefits
Homeowners, builders and community developers are more frequently using closed-cell spray polyurethane foam as an insulation and exterior material, due, in part,to its track record of performance during severe weather events. The material has been shown to increase the ability of homes to withstand the effects of flooding, storm surge and high winds. Longstanding endorsements for closed cell foams by such groups as the Federal Emergency Management Agency (FEMA), coupled with newer research by the University of Florida, highlight the effectiveness of these products in resisting flood and wind forces as well as structural damage.
Both types of foam are commonly used in most building applications and the choice for which to use can depend on many of the factors discussed above. Some spray-on foam insulation are inappropriate in specific applications. For example, you typically would not use open-cell foam below grade or in flotation applications where it could absorb water; this would negate its thermal performance because water is a poor insulator compared to air. Closed-cell foam would be a good choice where small framing sizes need the greatest R-value per inch possible. Closed-cell foam would be used for roofing applications.
Comparison of Closed-Cell Versus Open-Cell Insulation
| Insulation Types | |
| Closed Cell | Open Cell |
| Higher R Value (around 6.0 per inch) | Lower R Value( 3.5 per inch) |
| Greater Resistance | Lower Resistance |
| Solid Structure | Soft Structure |
| Requires more material | Less material needed |
| Higher Cost | Lower Cost |
| Hydro fluorocarbon (HFC) as blowing agent | Water as the blowing agent |
| Blocks most of the moisture | Provides more moisture-permeable surface area |
| ½ the sound resistance in normal frequency ranges | Incredibly effective as a sound barrier |
