Rigid panel is material used for insulation behind walls that have limited space. The panel is usually sold in sheets that can be cut to the desired dimensions with a knife, and can be mounted to a variety of surfaces for efficient insulation of walls, floors, ceilings, and more. The materials used to create the panels can vary, but slag wool is commonly used, as is fiberglass and polyurethane. These panels can be more expensive than other types of insulation, and in most cases, the panels are likely to be highly flammable.
The primary use of rigid panel is insulation, though in many cases other types of insulation may make better financial sense. If a wall cavity is exceptionally narrow, however, rigid panel can be used to provide the same amount of insulation with far less material taking up space. They are commonly used in the construction of cathedral ceilings as well as basement walls and other walls within a home, but they must be installed with fire-rated drywall to help prevent toxic fumes and potential fires. When the rigid panel burns, it will release toxic fumes that can be extremely harmful.
Some secondary benefits to using rigid panel include added structural integrity of walls and other structures, as well as added soundproofing capabilities. Sound insulation created by the paneling can help prevent transmission of vibration from one part of a home or structure to another, or even sounds from the outside of the structure to the inside and vice versa. This is, of course, only a secondary function, and other materials are available for more effective and intended soundproofing of a home or structure. The panels are usually waterproof or at east water-resistant, and while no panels should be exposed to constant sources of moisture, the paneling is less likely than some other types of insulation to break down during moisture exposure.
Other disadvantages, aside from the higher cost and flammability of the material, include susceptibility to UV damage as well as damage from solvents and chemicals. If the panel is exposed, it must be somehow covered or treated to protect it from degradation and breakdown. It can be brittle, depending on the types of materials used to construct the panel, though most of the panels are fairly strong and resistant to damage if they are installed and treated properly.