Remodeling is a great time to add extra insulation. Learn about your options to make your house more comfortable and lower heating and cooling costs.
You can't see insulation once it's installed, but you'll know it's there. Adding several hundred dollars worth of insulation can reduce your heating and cooling bill 10 to 30 percent. Attic insulation is a necessity—the attic is the primary location for insulation, and the easiest place to install it. When your home is well insulated, you can have a smaller HVAC system.
Insulation is designed to provide resistance to heat flow, but the amount and type of insulation you need depends on your house and climate. This resistance is measured by R-values; higher R-values equal higher resistance to heat flow. Local building codes suggest the minimum amount of insulation, but for the highest energy efficiency, you'll want to add even more. The Department of Energy offers a ZIP code insulation tool on their web site, www.eere.energy.gov, to help you determine the optimal amount of insulation for your area.
Some products, such as fiberglass batts, are better for additions or extensive remodeling projects where you'll have access to wall cavities, while other types, such as blown-in cellulose or spray-in foam, can be added to finished walls relatively easily. Rigid foam boards are often added to the exterior of a building (under weatherproof facing), often in conjunction with another type of insulation.
Here's a look at a few of the most common types of insulation and the advantages and disadvantages of each. We provide an idea about pricing here, but be aware that prices vary greatly depending on application and market price.
R-Value: 3.2 to 4.3 per inch of thickness
- Can be used in unfinished walls, floors, and ceilings Available in widths suited for standard stud and joist spacing, or in rolls that can be cut to the appropriate size
- Offers a cost-effective way to achieve desired R-value Some products are faced with a vapor retarder to help control moisture and prevent the growth of mold and mildew
- High-density products offer higher R-values for areas with limited cavity space, such as a cathedral ceiling
- Might not be the best choice for a limited remodeling project—installation requires you to pull off drywall or exterior sheathing on existing walls
- Requires careful installation—any gaps will decrease the overall R-value
- Fiberglass is scratchy, and the dust can irritate respiratory system
- In colder climates, you'll also need to install a vapor retarder to control moisture and condensation Moisture decreases R-value
- Starts about $0.50 per square foot when installed in 2x4-inch walls
R-Value: 3.4 to 6.5 per inch of thickness
- Can be installed into existing, finished walls
- Good for filling small, hard-to-reach nooks and crannies
- More airtight than other fibrous insulation installed in wall cavities
- Won'tsettle over time
- Closed-cell foam does not require an additional vapor retarder
- Must be installed by a professional
- More expensive than other types of insulation
- Open-cell foam should be used with an interior vapor retarder in cold climates
- Averages $1.50—$3 per square foot when installed in 2x4-inch walls
- In general, you'll pay 2—3 times more for spray-in foam than other types of insulation, but you can often save money by decreasing the size of your heating and cooling system
- Closed-cell foam is more expensive than open cell foam but offers a higher R-value
R-Value: 3.9 to 6.5 per inch of thickness
- Can be used on exterior walls (under facing), on foundations, and on the exterior of unvented, low-slope roofs
- Provides additional structural support
- Can be used in conjunction with other types of insulation to provide higher R-values for colder climates
- Provides high insulating value in a relatively thin space
- Must be covered with gypsum board (or another building-code approved material) inside or a weatherproof facing outside
- Doesn' fill wall cavities, so you'll want to use another insulating product as well
- Starts about $0.65 per square foot.
R-Value: 3.4 to 3.7 per inch of thickness
- Can be used in attics and wall applications
- Offers an eco-friendly choice because it's made from recycled wood fibers, such as newspapers
- Chemically treated for fire and moisture resistance
- Requires professional installation and/or special equipment to blow it into walls
- May settle over time, decreasing the overall R-value Absorbs more moisture than many other types of insulation
- R-value is reduced if insulation becomes wet
- Approximately $1 per square foot when installed in 2x4-inch walls
- (About $0.15 per square foot for every inch of attic insulation)