Which types of insulation are known for better moisture resistance?

Closed-cell spray foam and rigid foam boards are recognized for their superior moisture resistance due to their structural properties. Closed-cell spray foam contains tiny gas-filled cells that are closed off from each other, making it impermeable to moisture. This quality not only prevents water vapor from penetrating but also creates an effective air barrier, enhancing energy efficiency and preventing mold and mildew growth.

Rigid foam boards similarly exhibit low water absorption rates and high compressive strength. They are often used in applications where moisture is a significant concern, such as in below-grade walls or roofs. The combination of these characteristics makes closed-cell spray foam and rigid foam boards particularly effective for moisture control in building envelopes.

In contrast, other types of insulation listed do not provide the same level of moisture resistance. For example, cellulose insulation and fiberglass can absorb moisture over time, which may reduce their insulating effectiveness and lead to potential mold issues. Open-cell foam and cotton allow for greater air and moisture flow, making them less effective for moisture control. Wool and mineral wool, while somewhat resistant to moisture, do not generally offer the moisture barrier properties that closed-cell spray foam and rigid foam boards provide.