Open cell and closed cell foam insulation are both in the same category of building materials. The same equipment is used to make both products, and over 60% of the raw component ingredients are identical. The biggest discernible difference between the two products is density. At one cubic foot open cell foam insulation systems typically fall into a density spread of 0.45 lbs to 0.8 lbs providing a material consistency similar to memory foam mattress. For closed cell systems, one cubic foot of material falls into a density spread of 1.7 lbs to 2.2 lbs providing a material consistency similar to the sole of a running shoe.
It is important to note that while density of a foam insulation system is an identifier of closed cell status, the system must contain at least 90% closed cell content to be considered a bona fide closed cell system. Foam systems above 2.2 lbs or below 0.45 lbs are available, but typically are not used in interior use applications for construction.
The increased density of closed cell offers particular differences in comparison to open cell formulas, such as:
• Increased R-value per volume
• Increased resistance of water vapor transmission
• Increased rigidity providing superior structural integrity
• Increased price point over open cell
• Lower density open cell products have other benefits to offer, including:
• Offers the ability to air seal as effectively as closed cell but at a lower price point
• Water vapor transmission permeable
• Rapid expansion allows to fill voids CC can not
If budgets did not exist, closed cell would be the optimal material of choice for most all insulation applications. But because financial constraints are always a consideration we classify the use of closed cell under a few different recommendations given the climate zone of Southern New England and application dependency:
Small Wall or Roof Cavities
• Wall cavities that are 2x4 or smaller require the use of closed cell foam insulation to comply with building code requirements for minimum R-value.
• Cathedral Ceiling or Attic floor cavities that are 2x8 or smaller require the use of closed cell foam insulation to comply with building code requirements for minimum R-value.
High Humidity
• Unvented crawl spaces
• Crawl spaces with exposed earth floors
• Basements or crawl spaces with field stone foundation walls
• Buildings positioned on properties adjacent to open ocean exposed to a high wind and vapor drive
• Indoor Pool/Jacuzzi
High or Low Temperature Gradients
• Walk in coolers
• Walk in freezers
• Humidified wine cellars/humidors
If the above criteria do not apply, open cell foam insulation is an excellent alternative to closed cell because of its ability to custom apply to a variety of building geometry shapes, its ability to air seal and provide higher R-value over conventional insulation materials such as fiberglass and cellulose.
