Open Cell Foam Vs. Closed Cell - Go Green Energy Solutions

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Open Cell Foam Vs. Closed Cell

What’s the difference between open cell & closed cell? Others will say there’s no big difference. Some will tell you it’s all about price per square foot.
You want the facts necessary to make an educated decision
Polyurethane spray foam is often categorized as either “open cell” or “closed cell”. There are several major differences between the two types, leading to advantages and disadvantages for both, depending on the desired application requirements. It is an extremely versatile material that is available in a variety of final physical properties and densities, making it necessary for the end-user to have an understanding of these differences in order to choose the spray foam system that is best suited for the particular application requirements, meets code, and follows Best Building Practices.

Closed Cell Spray Foam

Go Green Solution’s closed cell spray foam is among the most efficient insulating materials for residential and commercial applications, with an R-value of 6.8 per inch. Common foam density for closed-cell polyurethane foam is approximately 1.7 to 2.0 pounds per cubic feet. This foam expands roughly 30 times its initial liquid size, and rarely requires trimming which results in little to no waste.

Go Green Solution’s closed-cell polyurethane foams are characterized by their rigidity and strength, in addition to the superior R-Value. These heavier and denser foams have what is known as a closed-cell structure, which means that the gas (EPA approved Honeywell 245fa) bubbles that form during the application process remain permanently locked into the cured foam. These millions of microscopic bubbles created during the manufacturing stage remain closed and intact, thus trapping the reaction gases. Therefore the R-Value of Go Green Solution’s closed cell foam is close to that of the reaction gas, or 6.8 per inch. Since there are no open interconnections between individual bubbles, the foam can not absorb water and also effectively diffuses (retards) the passage of water vapor.

According to most building codes, a vapor retarder must have a perm rating of less than 1.0; Go Green Solution’s closed-cell foam exceeds this standard. And, very importantly, due to the closed-cell structure and higher density range, it provides the optimum strength increasing shear and racking stability by up to 300%.

One additional note concerning closed cell foam is that some companies market and install closed cell foams without this 245fa (or comparable inert gas) blowing agent. These products begin to lose some of the benefits that are characteristic of true closed-cell polyurethane foams.

Without this blowing agent the foam may suffer a significant amount of vapor diffusion and/or vapor barrier qualities and should therefore create concern when being used for these reasons, such as under floors or in the exterior walls of old wood-sided homes without code approved vapor retarders for example.

Open Cell Spray Foam

Go Green Solution's open cell spray foam is also referred to as ½ pound or low density foam. This foam expands to over 100 times its initial liquid size and may require trimming and disposal of the excess waste material after application. The physical characteristics of Go Green Solution’s open-cell polyurethane foam usually include a softer “spongier” appearance, as well as lower strength and rigidity than closed-cell foams.

Open cell foam cures soft while the irregular bubbles which form during the expansion-reaction process remain open and interconnected. Go Green Solution's open cell foam derives its R value of 3.8 per inch from the dormant air within the open bubble pockets which is about half that of closed-cell foam. The R-Value of open cell foam is quoted close to that of conventional fiberglass and cellulose insulation based on the same principle of trapping dormant air. These similarly quoted insulation R-values are very misleading since open cell foam is an air barrier and may significantly slow moisture transfer relative to these competing insulations. Under real life conditions open cell foam performs at its stated R-value whereas the R-value of fiberglass and cellulose degrade do to air flow (convection) through and within the material, commonly poor installation practices, and extreme temperature differences.

Please view “The R Fairy Tale” (PDF file) and “Oak Ridge Labratory’s”(3 PDFs in zip) study on fiberglass insulation for more information about the inaccuracies of R-values. Open cell foam significantly slows down convection through and within the wall cavity. Open cell spray foam, however, is more permeable to water vapor than closed-cell, with perm ratings of approximately 16 per 3 inches thickness, and therefore is not a code approved vapor barrier/retarder. Open cell foam should not be used in exterior applications, such as underneath a raised house, due to its inability to retard moisture flow. However, Go Green Solution's open cell foams are incredibly effective as a sound barrier, having about twice the sound resistance in normal frequency ranges as closed-cell foam.

Applications that typically use open cell foam include residential construction insulation, under roof trusses for “conditioned attics”, and for sound deadening in media rooms, etc. Closed-cell foam, while a superior insulating product used in residential construction, is also used in a variety of commercial and industrial applications because of the excellent strength and insulating properties and vapor barrier qualities which may be required by building codes.

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