Comparing Open-Cell and Closed-Cell Spray Foam: Key Differences and Applications

Sprayed polyurethane foam (SPF) is a versatile insulating material based on chemical composition, and because the material sprayed with foam does not deform over time, it is often used in the insulation system of houses. It consists of two main components: isocyanates and a mixture of additives, including polyols and catalysts, which are mixed on site to form a strong insulating layer. There are two main types of spray foam: open-cell foam and closed-cell foam, each with different characteristics and uses.

Open-Cell Spray Foam

Open-hole spray foam has a lower cost and greater expansibility, and can be selected when filling larger Spaces. Because of its greater flexibility, it can be removed more easily and can also be filled with insulation for hard-to-reach corners. Open-cell foam has a cell structure similar to tiny bubbles with openings that allow air to circulate. While it provides air tightness, it does not provide a moisture barrier because its permeability allows water to pass through. It has an R-value (a measure of its insulating ability) of about 3.5 to 3.8 per inch, making it suitable for applications where air flow is required but moisture resistance is not essential. It is commonly used in interior walls, attics, and areas that require sound insulation, as its open-hole construction also provides excellent noise reduction.

Closed-Cell Spray Foam

Pores that are tightly grouped together to form a denser structure are called closed-cell foams. Closed-cell spray foam is denser and stiffer, creating a strong barrier against air and moisture. Its tightly packed pores prevent air and moisture from penetrating, making it an effective moisture barrier. It expands at a lower rate than open-cell foam, but insulates better, with an R value of about 6.0 per inch. The higher the R-value, the more effectively closed-cell foam resists heat flow, making it ideal for external applications that require higher insulation values and moisture protection, such as roofs, foundations, and walls. Despite the higher cost, closed-cell foam is usually preferred in areas where space is limited but maximum insulation is needed.

In summary, both open-cell and closed-cell spray foams are effective insulators but differ in their properties and applications. Open-cell foam is more affordable, expands more, and allows air circulation, while closed-cell foam is denser, acts as a moisture barrier, and offers a higher R-value. The choice between the two depends on specific project needs, including moisture protection, insulation efficiency, and budget.