Open-Cell or Closed-Cell Spray Foam?
Open-Cell Spray Foam
The cheapest spray foam option is known as open-cell. So called because the bubbles inside of the foam never completely close. As the foam expands, air gets trapped in between the broken bubbles. This divides the space into billions of tiny air pockets that slow down heat as it tries to pass through. Open-cell spray foam is a much softer type of foam because of the broken bubbles. These bubbles allow water to pass through them, which can be good or bad depending on the application. Although open-cell spray foam does a great job at filling in and around wires, pipes and other obstacles, it’s insulating power is not all that spectacular: R-4 per inch.
