But in older homes, it is one of the most important and cost-effective energy-saving building materials you can invest in. Without adequate insulation, the other energy-efficient components in your house won't perform effectively. It resists the flow of heat out of your house in winter and into your house in summer. Insulate your house properly and use less energy in winter for heating and less in the summer for cooling.

The common types of insulation are fibrous, cellular, radiant barrier and reflective coating.

A material’s R-value is the measure of its resistance to heat flow. It is important to know the R-value because many states or regions require that a roof system have a minimum amount of thermal resistance. The way it works is simple: the higher the R-value, the more the material insulates.

Fiberglass insulation expands when the package is opened. They compress the material at the factory. When opened, it may expand 500 to 1,000 percent! So, don't open the material until your contractor is ready.

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