Rigid panel

Rigid panel insulation is made from fibrous materials (fiberglass, rock and slag wool) or from plastic foam. They are sometimes sold in sections designed to fit tightly in standard wall cavities. When sold this way, they are called "batts", and they come in different thicknesses to match the depth of wall cavities, for example, approx. 5½ inches to match a 2 x 6 inch wall cavity.

Where rigid panels are most often used:

There are many types of rigid cellular polystyrene (RCPS). Styrofoam is simply Dow Chemical's brand name, and does not refer to any particular type of RCPS. Some polystyrene uses up to 50% recycled resin, including post-consumer plastic. Several states have banned polystyrene that uses CFCs as blowing agents.

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