The Science of Experience



When to Use Open and Closed Spray Foam Insulation

Posted by Becky Eades

Oct 13, 2015 11:30:00 AM


Open and closed spray foam insulation are both effective ways to seal a building against heat transfer. However, the unique way in which closed cell foams work makes them particularly effective at sealing out, not only air, but also moisture transfer.

Both types of spray foam start out as a liquid. As open cell spray foam is applied, it traps air which causes it to expand. The trapped air helps to stabilize its R-value, giving it a high degree of insulating efficiency. 

Closed-cell foam insulation, on the other hand, is mixed with a special blowing agent. As the foam and agent are applied, they heat up and cause the foam to exude a hot gas. That gas gets trapped in the foam and shrinks as it closes. This causes the foam to firm up, but it also reduces its insulating capabilities.

Open cell foams offer the same R value for years after they are first applied. Closed-cell foams, on the other hand, take about six months to stabilize. However, once they have stabilized, they still provide excellent protection in much less space than other types of foam insulation. Closed cell systems also reinforce walls and roofs, adding strength, and are also exceptionally good at repelling moisture. At the same time, though, they also allow buildings to breathe.


Contact the experts at NCFI to learn more about our different foam insulation products, plus learn about our extensive training and safety programs. 

Topics: Energy Efficiency, Low Costs