Sealing and insulating the "envelope" or "shell" of your home — its outer walls, ceiling, windows, doors, and floors — is often the most cost effective way to improve energy efficiency and comfort. Estimates indicate that a knowledgeable homeowner or skilled contractor can save up to 20% on heating and cooling costs (or up to 10% on their total annual energy bill) by sealing and insulating.
To Seal and Insulate with ENERGY STAR:
- Seal air leaks throughout the home to stop drafts,
- Add insulation to block heat loss in winter and heat gain in summer,
- Choose ENERGY STAR qualified windows when replacing windows.
If your attic is accessible and you like home improvement projects, you can Do-It-Yourself with help from this Do-It-Yourself Guide to Sealing and Insulating which offers step-by-step instructions for sealing common air leaks and adding insulation to the attic.
You can also hire a contractor who will use special diagnostic tools to pinpoint and seal the hidden air leaks in your home.
Many air leaks and drafts are easy to find because they are easy to feel — like those around windows and doors. But holes hidden in attics, basements, and crawlspaces are usually bigger problems. Sealing these leaks with caulk, spray foam, or weather stripping will have a great impact on improving your comfort and reducing utility bills. Click on the house diagram to see common air leak locations that you should aim to seal.
Homeowners are often concerned about sealing their house too tightly; however, this is very unlikely in most older homes. A certain amount of fresh air is needed for good indoor air quality and there are specifications that set the minimum amount of fresh air needed for a house. If you are concerned about how tight your home is, hire a contractor, such as a Home Energy Rater, who can use diagnostic tools to measure your home's actual leakage. If your home is too tight, a fresh air ventilation system may be recommended.
After any home sealing project, have a heating and cooling technician check to make sure that your combustion appliances (gas- or oil-fired furnace, water heater, and dryer) are venting properly
Insulation keeps your home warm in the winter and cool in the summer. There are several common types of insulation — fiberglass (in both batt and blown forms), cellulose, rigid foam board, and spray foam. Reflective insulation (or radiant barrier) is another insulating product which can help save energy in hot, sunny climates.
When correctly installed with air sealing, each type of insulation can deliver comfort and lower energy bills during the hottest and coldest times of the year.
Insulation performance is measured by R-value — its ability to resist heat flow. Higher R-values mean more insulating power. Different R-values are recommended for walls, attics, basements and crawlspaces, depending on your area of the country. Insulation works best when air is not moving through or around it. So it is very important to seal air leaks before installing insulation to ensure that you get the best performance from the insulation.
Recommended Levels of Insulation
Insulation level are specified by R-Value. R-Value is a measure of insulation’s ability to resist heat traveling through it. The higher the R-Value the better the thermal performance of the insulation. The table below shows what levels of insulation are cost-effective for different climates and locations in the home.
Recommended insulation levels for retrofitting existing wood-framed buildings
||Add Insulation to Attic
||Existing 3–4 Inches of Insulation
||R30 to R49
||R25 to R30
||R30 to R60
||R25 to R38
||R13 to R19
||R30 to R60
||R25 to R38
||R19 to R25
||R38 to R60
||R25 to R30
|5 to 8
||R49 to R60
||R38 to R49
||R25 to R30
Wall Insulation: Whenever exterior siding is removed on an
Uninsulated wood-frame wall:
- Drill holes in the sheathing and blow insulation into the empty wall cavity before installing the new siding, and
- Zones 3–4: Add R5 insulative wall sheathing beneath the new siding
- Zones 5–8: Add R5 to R6 insulative wall sheathing beneath the new siding.
Insulated wood-frame wall:
- For Zones 4 to 8: Add R5 insulative sheathing before installing the new siding.
To get the biggest savings, the easiest place to add insulation is usually in the attic. A quick way to see if you need more insulation is to look across your uncovered attic floor. If your insulation is level with or below the attic floor joists, you probably need to add more insulation. The recommended insulation level for most attics is R-38 (or about 12–15 inches, depending on the insulation type). In the coldest climates, insulating up to R-49 is recommended.
In houses with forced-air heating and cooling systems, ducts are used to distribute conditioned air throughout the house. In a typical house, however, about 20 percent of the air that moves through the duct system is lost due to leaks and poorly sealed connections. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set.
Because some ducts are concealed in walls and between floors, repairing them can be difficult. However, exposed ducts in attics, basements, crawlspaces, and garages can be repaired by sealing the leaks with duct sealant (also called duct mastic). In addition, insulating ducts that run through spaces that get hot in summer or cold in winter (like attics, garages, or crawlspaces) can save significant energy.
Additionally, if you are replacing your forced-air heating and cooling equipment, make sure your contractor installs the new system according to Energy Star quality installation guidelines. A quality installation will include a thorough inspection of your duct system, including proper sealing and balancing of ductwork, to help ensure that your new system delivers the most comfort and efficiency.
How do you know that your home has poorly performing ducts?
- you have high summer and winter utility bills;
- you have rooms that are difficult to heat and cool;
- you have stuffy rooms that never seem to feel comfortable;
- your ducts are located in an attic, crawlspace, or the garage;
- you find tangled or kinked flexible ducts in your system.
Benefits of Duct Sealing
A duct system that is well-designed and properly sealed can make your home more comfortable, energy efficient, and safer.
Sealing and insulating ducts can help with common comfort problems, such as rooms that are too hot in the summer or too cold in the winter.
Indoor Air Quality
Fumes from household and garden chemicals, insulation particles, and dust can enter your duct system, aggravating asthma and allergy problems. Sealing ducts can help improve indoor air quality by reducing the risk of pollutants entering ducts and circulating through your home.
During normal operation, gas appliances such as water heaters, clothes dryers, and furnaces release combustion gases (like carbon monoxide) through their ventilation systems. Leaky ductwork in your heating and cooling system may cause “backdrafting,” where these gases are drawn back into the living space, rather than expelled to the outdoors. Sealing leaks can minimize this risk.
Leaky ducts can reduce heating and cooling system efficiency by as much as 20 percent. Sealing and insulating ducts increases efficiency, lowers your energy bills, and can often pay for itself in energy savings. Plus, if you’re planning to install new heating and cooling equipment, a well-designed and sealed duct system may allow you to downsize to a smaller, less costly heating and cooling system that will provide better dehumidification.
Protect the Environment
Energy used in our homes often comes from the burning of fossil fuels at power plants, which contributes to smog, acid rain, and global warming. Simply put, the less energy we use in our homes, the less air pollution we generate. By sealing your ducts and reducing the amount of energy necessary to comfortably heat or cool your home, you can reduce the amount of air pollution generated.
Simple Steps to Improving Duct Performance
Because ducts are often concealed in walls, ceiling, attics, and basements, repairing them can be difficult. But there are things that you can do to improve duct performance in your house.
Some homeowners choose to take on duct sealing as a do-it-yourself project. Start by sealing air leaks using mastic sealant or metal tape and insulating all the ducts that you can access (such as those in attics, crawlspaces, unfinished basements, and garages). Never use duct tape, as it is not long-lasting. Also, make sure that the connections at vents and registers are well-sealed where they meet the floors, walls, and ceiling. These are common locations to find leaks and disconnected ductwork.
Many homeowners choose to work with a professional contractor for duct improvement projects. Most heating and cooling equipment contractors also repair ductwork.
Common Duct Problems And Solutions
A. Leaky, torn, and disconnected ducts
B. Poorly sealed registers and grills
C. Leaks at furnace and filter slot
D. Kinks in flexible ductwork restricting airflow
E. Properly sealed ducts
F. Registers and grills tightly sealed
G. Sealed furnace and filter slot
H. Well-insulated ducts in unfinished areas
I. Straightened flexible ducts with improved airflow