Improving your home’s insulation and sealing air leaks are the fastest and most cost-effective ways to reduce energy waste and make the most of your energy dollars. Be sure to seal air leaks before you insulate, because insulating materials won’t block leaks.
Sealing Air Leaks
Air leaks can waste a lot of your energy dollars. One of the quickest energy and money saving tasks you can do is caulk, seal, and weather strip all seams, cracks, and openings to the outside.
Tips for Sealing Air Leaks
- Test your home for airtightness. On a windy day, carefully hold a lit incense stick or a smoke pen next to your windows, doors, electrical boxes, plumbing fixtures, electrical outlets, ceiling fixtures, attic hatches, and other places where air may leak. If the smoke stream travels horizontally, you have located an air leak that may need caulking, sealing, or weatherstripping.
- Caulk and weatherstrip doors and windows that leak air.
- Caulk and seal air leaks where plumbing, ducting, or electrical wiring comes through walls, floors, ceilings, and soffits over cabinets.
- Install foam gaskets behind outlet and switch plates on walls.
- Inspect dirty spots in your insulation for air leaks and mold. Seal leaks with low-expansion spray foam made for this purpose and install house flashing if needed.
- Look for dirty spots on your ceiling paint and carpet, which may indicate air leaks at interior wall/ceiling joints and wall/floor joists, and caulk them.
- Cover single-pane windows with storm windows or replace them with more efficient double-pane low-emissivity windows. See the Windows section for more information.
- Use foam sealant on larger gaps around windows, baseboards, and other places where air may leak out.
- Cover your kitchen exhaust fan to stop air leaks when not in use.
- Check your dryer vent to be sure it is not blocked. This will save energy and may prevent a fire.
- Replace door bottoms and thresholds with ones that have pliable sealing gaskets.
- Keep the fireplace flue damper tightly closed when not in use.
- Seal air leaks around fireplace chimneys, furnaces, and gas-fired water heater vents with fire-resistant materials such as sheet metal or sheetrock and furnace cement caulk.
Fireplace flues are made from metal, and over time repeated heating and cooling can cause the metal to warp or break, creating a channel for air loss. To seal your flue when not in use, consider an inflatable chimney balloon. Inflatable chimney balloons fit beneath your fireplace flue when not in use, are made from durable plastic, and can be removed easily and reused hundreds of times. If you forget to remove the balloon before making a fire, the balloon will automatically deflate within seconds of coming into contact with heat.
Insulation is made from a variety of materials, and it usually comes in four types: rolls and batts, loose-fill, rigid foam, and foam-in-place.
Rolls and batts—or blankets—are flexible products made from mineral fibers, such as fiberglass and rock wool. They are available in widths suited to standard spacing of wall studs and attic or floor joists: 2 in. x 4 in. walls can hold R-13 or R-15 batts; 2 in. x 6 in. walls can use R-19 or R-21 products.
Loose-fill insulation is usually made of fiberglass, rock wool, or cellulose in the form of loose fibers or fiber pellets. It should be blown into spaces using special pneumatic equipment. The blown-in material conforms readily to odd-sized building cavities and attics with wires, ducts, and pipes, making it well suited for places where it is difficult to effectively install other types of insulation.
Rigid foam insulation is typically more expensive than rolls and batts or loosefill insulation, but it is very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches. Foam insulation R-values range from R-4 to R-6.5 per inch of thickness, which is up to 2 times greater than most other insulating materials of the same thickness.
Foam-in-place insulation can be blown into walls, on attic surfaces, or under floors to insulate and reduce air leakage. You can use the small pressurized cans of foam-in-place insulation to reduce air leakage in holes and cracks such as window and door frames, and electrical and plumbing penetrations.
There are two types of foam-in-place insulation: closed-cell and open-cell. Both are typically made with polyurethane. With closed-cell foam, the high-density cells are closed and filled with a gas that helps the foam expand to fill the spaces around it. Closed-cell foam is the most effective, with an insulation value of around R-6.2 per inch of thickness.
Open-cell foam cells are not as dense and are filled with air, which gives the insulation a spongy texture. Open-cell foam insulation value is around R-3.7 per inch of thickness.
The type of insulation you should choose depends on how you will use it and on your budget. While closed-cell foam has a greater R-value and provides stronger resistance against moisture and air leakage, the material is also much denser and is more expensive to install. Open-cell foam is lighter and less expensive but should not be used below ground level where it could absorb water. Consult a professional insulation installer to decide what type of insulation is best for you.
Consider factors such as your climate, home design, and budget when selecting insulation for your home.
- Use higher R-value insulation, such as spray foam, on exterior walls, and in cathedral ceilings to get more insulation with less thickness.
- Install attic air barriers such as wind baffles along the entire attic eave to help ensure proper airflow from the soffit to the attic. Ventilation helps with moisture control and reducing summer cooling bills, but don’t ventilate your attic if you have insulation on the underside of the roof. Ask a qualified contractor for recommendations.
- Be careful how close you place insulation next to a recessed light fixture—unless it is insulation contact (IC) rated—to avoid a fire hazard. See the Lighting section for more information about recessed lights.
- Follow the manufacturer’s installation instructions, and wear the proper protective gear when installing insulation.
Long-Term Savings Tips
One of the most cost-effective ways to make your home more comfortable year-round is to add insulation to your attic, including the attic trap or access door, which is relatively easy. To find out if you have enough attic insulation, measure the thickness of the insulation. If it is less than R-30 (11 inches of fiberglass or rock wool or 8 inches of cellulose), you could probably benefit by adding more.
If your attic has enough insulation and proper air sealing, and your home still feels drafty and cold in the winter or too warm in the summer, chances are you need to add insulation to the exterior walls. This is more expensive and usually requires a contractor, but it may be worth the cost—especially if you live in a very cold climate. If you replace the exterior siding on your home, consider adding insulation at the same time.
You may also need to add insulation to your crawl space or basement. Check with a professional contractor for recommendations.
New Construction and Additions
In most climates, you will save money and energy when you build a new home or addition if you install a combination of cavity insulation and insulative sheathing. Reduce exterior wall leaks by taping the joints of exterior sheathing and caulking and sealing exterior walls. Cavity insulation can be installed at levels up to R-15 in a 2 in. x 4 in. wall and up to R-21 in a 2 in. x 6 in. wall.
These help to reduce the energy that would otherwise be lost through the wood frame. For more customized recommendations, see the ZIP Code Insulation Calculator.
Consider products that provide both insulation and structural support, such as structural insulated panels (SIPs), and masonry products like insulating concrete forms. Visit the Energy Savers website or more information on structural insulation.
You should consider attic or roof radiant barriers (in hot climates), reflective insulation, and foundation insulation for new home construction. Check with your contractor for more information about these options.
Tips for Finding a Contractor
- Look for licensed, insured, and certified contractors
- Get three bids with details in writing
- Ask about previous experience
- Check references
- Ask neighbors and friends for recommendations
- Focus on local companies
Should I Insulate My Home?
Insulate your home when:
- You have an older home and haven’t added insulation. Homes built before 1950 use about 60% more energy per square foot than those built in 2000 or later.
- You are uncomfortably cold in the winter or hot in the summer— adding insulation creates a more uniform temperature and increases comfort.
- You build a new home or addition or install new siding or roofing.
- You pay high energy bills.
- You are bothered by noise from outside—insulation muffles sound.
How Much Insulation Does My Home Need?
For insulation recommendations tailored to your home, visit the DOE Zip Code Insulation Calculator.