Different Types of Insulation for Attics

Different Types of Insulation for Attics

Control your house's temperature -- and your utility bills -- with attic insulation

By Shelly McRae

Insulation in Attic
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Insulating your attic helps control your heating and cooling bills. It is particularly effective in controlling heat loss, as hot air rises in search of cooler air. In colder climates, an attic without insulation allows the heated air to continually escape, making the furnace work harder. In warmer climates, where cooling is important, a well-insulated and well-ventilated attic will aid in maintaining that cooled air within the living spaces below the attic.


Fiberglass insulation is pink and fluffy. When used to insulate an attic, fiberglass insulation can be installed in the ceiling, walls and floor. The effectiveness of fiberglass insulation is measured in R-value, meaning thermal resistance to heat flow. The higher the R-value of insulation, the more resistant it is to heat flow. Fiberglass comes in precut rolls, batts and blankets. Rolls are available in various widths and lengths and can be cut to suit the framing of your attic. Batts are pre-cut to suit 8-foot walls. Blankets come in pre-cut sizes and are used to lay over existing insulation that may have compressed. Loose fill fiberglass is also available. This type of insulation is blown into the space and is used to cover old insulation or reach difficult spaces.


This type of insulation is composed mainly of recycled paper (up to 75 percent), primarily newsprint. The R-value of cellulose is similar to that of fiberglass, but it is also more resistant to heat loss in lower temperatures. That means cellulose provides better insulation in colder climates. Cellulose is blown directly into the cavities of the walls of the attic, between the rafters and studs, using a spray pump. Cellulose is more resistant to compression than fiberglass, but due to its organic content, may allow for mold or mildew growth. It is less resistant to moisture than fiberglass, and your attic should be well-ventilated to keep the cellulose free from condensation.

Mineral Wool

Manufactured from steel slag, mineral wool, sometimes referred to as rock wool, is comprised of dirt and limestone, and is chemically treated. It's spun into a fibrous material that can be used for insulation. As an insulator, mineral wool does not rot, burn or melt. Because of its inorganic properties, it is resistant to mold and mildew. It is also more resistant to compression than both fiberglass and cellulose.


Rigid insulation may be polystyrene, polyisocyanurate or compressed mineral wool. Rigid insulation comes in boards and can be used in conjunction with other loose-fill insulations. Though more commonly used in exterior applications or in basements, it can be used in an attic.

About the Author

Shelly McRae is a regular contributor to DexKnows. She has experience with hydroponic gardening and other areas of the home improvement industry.

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