How Does Roof Insulation Work?

About Insulation

• Insulation is designed to limit the transfer of heat through the roof of your home. The effectiveness of your insulation mainly depends on its type, quantity and installation. The effectiveness of each type of insulation is measured by its R-factor. This rating system defines the resistance to heat flow that the insulation provides. This rating is affected by several factors, including the type of insulation, density and thickness. Correct insulation and local climate conditions have a strong impact on the actual benefits your insulation provides.

Insulation Properties

• There are several properties of insulation that have a direct impact on its effectiveness. Adding more insulation will decrease the transfer of heat in proportion to the R-value of the insulation. However, insulation that is compressed has a reduced insulating capacity. Layering additional heavy insulation over your existing roof insulation can compress existing insulation, decreasing its effectiveness. Always install layered insulation with lighter materials on the top, or use rigid insulation secured above your existing insulation to prevent compression. Ceiling insulation should cover every avenue that heat can escape through to ensure maximum effectiveness. Filling small gaps with foam insulation will also increase the effectiveness of your insulation by preventing leaks.

Types of Insulation

• There are five basic types of insulation used in the home. Each has specific benefits and drawbacks. Blankets are rolls of flexible insulation, often made of fiberglass, are designed to rest between joists. This type is relatively easy to install but requires open spaces to work in. Fill insulation consists of loose fibers or pellets that are installed using a blower. These have the advantage of easily fitting into irregular spaces but typically require professional installation. Foam insulation is a chemical mixture that is sprayed into place using specialized equipment. Rigid insulation takes the form of boards and formed pipe coverings. This type of insulation is often faced with reflective foil to improve its efficiency. Reflective insulation is typically constructed from aluminum and is installed in flat sheets across joists to reduce the transfer of heat.

Insulation Efficiency

• Insulation prevents heat from moving from one location to another through conduction, convection or radiation. One of the most common problems with ceiling insulation results from gaps in the insulation that allow heat to pass through. Locating and plugging these gaps will increase the efficiency of your ceiling insulation. Since insulation is designed to improve the efficiency of your heating and cooling system, adding insulation to the HVAC vents in your roof can decrease your energy costs.