Which materials are examples of air-permeable insulation?

Air-permeable insulation materials are designed to allow air to pass through them, which can be beneficial in certain applications, especially where controlling humidity and air movement is important. The correct choice includes materials like fiberglass batts, cellulose hung in fabric, and open-cell spray foam.

Fiberglass batts are effective for insulation while allowing some air movement, which can help manage moisture levels within wall assemblies. Cellulose that is installed in a fabric can enable air circulation, contributing to breathability while still providing thermal insulation. Open-cell spray foam has a structure that is less dense than closed-cell variants, which permits air to flow through, allowing moisture to escape and providing thermal performance at the same time.

In contrast, the other options include materials that are typically not air-permeable. Polyurethane foam and closed-cell foam create airtight seals, making them effective thermal insulators but not air-permeable. Rigid boards and polystyrene sheets are also designed for high thermal resistance without allowing air flow. Reflective barriers focus on radiant heat regulation rather than the air permeability concept, and cork, while a natural product, does not function like the air-permeable insulations in the first option.