Insulating the home

Insulation is usually discussed in terms of R-values: higher R-values represent better insulation and greater resistance to heat flow. Typically, higher R-values are recommended for ceilings than for walls and floors. Although your local building codes should specify R-values for homes, these building codes often represent a minimum level of insulation necessary for comfort, rather than a level recommended for optimal energy efficiency.

Insulation is available in a variety of forms, including batts and blankets, rigid board, and loose fill. Each type is made to fit in a different part of your house. Batts, usually made of fiberglass or rock wool, are made to fit between the studs in your walls or between the joists of your ceilings or floors. Rolls or blankets, also usually made of fiberglass, can be laid over the floor in the attic. Loose-fill insulation, usually made of fiberglass, rock wool or cellulose, can either be poured in or blown in to spaces. Rigid foam boards are made of polyisocyanurate, extruded polystyrene (XPS or blueboard), expanded polystyrene (EPS or beadboard), or other materials. These boards are lightweight, provide structural support, and generally have an R-value of 4 to 7 per inch.

When adding insulation to your home, you will probably use batts or blankets on attic floors, to insulate first-story floors from crawl spaces or unheated basements, or to insulate exterior walls. Rigid boards can be added to basement walls, exposed foundations, cathedral ceilings, and exterior walls. If you are removing the plasterboard from exterior walls (or adding new walls), you should consider using rigid board insulation in exterior walls. Both types of insulation—batts and rigid boards—can be used to insulate the access openings to attic spaces.

Loose-fill insulation can be blown or poured into existing walls or attics. Loose-fill insulation requires less energy to produce than other forms of insulation, and cellulose loose-fill insulation is made from recycled materials.