What Is R-Value?
The capacity of an insulating material to resist heat flow is called its R-value. The higher the material’s R-value, the better it insulates. Recommended R-values differ for various parts of your home and vary by region. Check with your local utility company or insulation manufacturer’s literature.
| Type | R-Value per Inch | Cost | Pros and Cons |
 Fiberglass |
R-3.0 to R-3.8 | Low | Pros: Easy-to-install batts press into place, made in standard stud and joist widths; available with Kraft paper facing attached. Cons: Can be irritating to installer’s skin and lungs; susceptible to air gaps during installation. |
 Loose Fill |
R-2.2 to R-4.0 | Low | Pros: Better coverage in irregular spaces and over trusses; can be poured or blown into walls. Cons: Messy to work with; quality can vary; lower R value; can shift or settle; may need to rent insulation blower. |
 Extruded Foam |
R-5.2 | High | Pros: High compressive strength; great performance underground Cons: Cover with drywall or other fireproof material. |
 Expanded Foam |
R-3.8 to R-4.3 | Medium | Pros: Lowest-cost among foams. Cons: Not for underground cover with drywall or fireproof material. |
| Sprayed urethane foam | R6 0 to R7.3 | High | Pros: Makes a tough, seamless thermal and vapor barrier cove s irregular surfaces adds structural strength. Cons: Must be professionally applied. Very expensive. Cover with drywall or other fireproof material. |
Where Energy Goes
To improve your home’s energy efficiency while making the best use of your time and money, take a look at where heat loss typically occurs. Focus first on the simple steps that provide the biggest benefit. Air leaks -- especially those in the attic -- are responsible for the majority of a home’s heat loss, followed by poor-performing windows and doors. Next on the list of energy wasters is heat loss through floors, foundations and basements. Since walls account for only about 13 percent of the heat loss in a house -- and retrofitting wall insulation is difficult and expensive -- this area may be lower on your priority list. Curbing heat loss through the ceiling is often the easiest approach, because attic insulation is inexpensive and easy to add.
Air Leaks
The typical house has many small air leaks in the ceiling. Their area, when combined, can be equivalent to the size of a small chimney. The drafting this creates pulls heated air out through the attic and sucks cool air in from around windows and doors. This is also a primary cause of ice dams. Plumbing vents, open soffits, recessed lights, spaces between joists and the attic hatch are all areas that can benefit from sealing and insulating.