Deciding on the proper insulation for your project can take time given the many different types readily available on the market. While many kinds may be available, they often perform in very different ways and some are much better suited for certain applications than others. Knowing the key differences is the first step to selecting the right type of insulation for your application.
Open Cell vs. Closed Cell Foams
Foams are broadly classified by the structure of the cells in the foam, either open or closed. Whether or not more than half of a foam’s cells are open or closed has a tremendous impact on many of the foam’s properties and whether or not it is classified as an open or closed cell foam.
Open Cell Foams
Similar to rubber, open cell foams are combined with an inflating agent during the manufacturing process. The agent expands as the foam hardens or vulcanizes. Some of the most common open cell foams are:
Reticulated foam
Polyurethane foam
Open cell rubber
Many open cell foams have a soft, springy appearance and will quickly return to their original shapes after being deformed. These flexible foams make for great sealing applications and are often found in insulation, sound and shock absorption, and upholstery.
Closed Cell Foams
The cells in a closed cell foam are completely enclosed and do not interconnect with other cells. Typically manufactured with blowing agents, closed cell foams are often stronger and more resilient than open cell foams. Common closed cell foams include:
EPDM
Neoprene
EPS
XPS
Polyiso
The trapped bubbles of gas in the foam give closed cell foams excellent insulation properties. The closed nature of the cells also decreases water’s ability to permeate the foam.
Closed Cell Insulation Performance
The tight-packed nature of the cells in closed cell foam insulation tends to give these types of foam a higher R-value per inch than open cell insulation types. In addition to being better insulators, closed cell foams tend to be denser and structurally stronger. Dimensional stability and resistance to water, mildew, and chemicals are all also higher in closed cell foams.
Closed Cell Insulation Installation
The dimensional stability of closed cell foams and the lightweight nature of the foam board makes them easy to install on job sites. The resilience of closed cell foam gives it the versatility to work in cavity insulation or in an exterior insulation application.
Cavity Insulation
After the framing members are installed and exterior sheathing has been secured, closed cell foam can be installed in the cavities between the framing studs. Closed cell foam is strong but can be easily cut so that it can be trimmed to the right size just before installation.
Adhesive can be applied to the face of the foam board or closed-cell spray foam can be applied to the perimeter of the wall cavity. The closed cell foam board is then pressed into the cavity and sealed tight against the exterior sheathing. Spray foam or tape can be used to seal any seams between panels of foam board.
Continuous Insulation
While often used in interior cavity insulation applications, closed cell foam is uniquely suited for performance as an exterior or continuous insulation. After the framing members have been erected and exterior sheathing applied, closed cell foam boards are installed on the outside of the sheathing.
Fasteners are used to penetrate through the closed cell foam boards and into the framing members. A few fasteners are used for each board to keep the boards tightly in place. Once all the foam boards have been fastened, tape is used to seal the gaps between the insulation panels.
Rmax Polyiso: The Closed Cell Foam of Choice
Closed cell foams bring exceptional thermal performance, structural rigidity, and resistance to moisture, however, not all closed cell foams are created equal. Rmax polyiso exceeds other closed cell foams, like EPS and XPS, in R-value per inch performance. Polyiso also has a more tightly packed cell network to enhance many of the properties of closed cell foams like moisture resistance.
One of the properties that truly sets Rmax polyiso apart from XPS and EPS is its high-temperature performance. Polyiso, a thermoset, performs very differently from XPS and EPS, both thermoplastics, when exposed to elevated temperatures. While polyiso chars and hardens, XPS and EPS both soften and melt as the temperature increases.
When installed in a continuous insulation application, the surface temperature of the insulation can reach surprisingly high temperatures. Under these conditions, XPS and EPS may not stay installed in the same condition as the day they were installed. Shifting of the insulation means the building may not perform as well over time.
When choosing a closed cell foam, the performance of Rmax polyiso makes the decision easy. For a closed cell foam that will perform exceptionally throughout the life of the building, choose Rmax polyiso.
Reach out to our team of closed cell foam experts today to learn more about why polyiso should be your closed cell foam of choice!