How to Save on Heating Costs With Insulation

rolling out insulation batting
  • 4-40 hours
  • Intermediate
  • 500-2,500
What You'll Need
Insulation materials
Furring strips
Weather stripping
Face mask
Heavy-duty shears
Hand cleaner
Sharp knife
Vapor barrier
What You'll Need
Insulation materials
Furring strips
Weather stripping
Face mask
Heavy-duty shears
Hand cleaner
Sharp knife
Vapor barrier

Heating costs, especially in the winter, can be hefty. To save on these costs, you can add insulation to your home. Without insulation, warm air generated by your furnace escapes through gaps around your windows, doors, walls, ceilings, and roof. And, when the weather is warm, insulation lowers the amount of chilled air from your air conditioner escaping, preventing your home from heating up in the first place. Check out this handy guide for more information to get started.

Disclaimer: Check your state and local codes before starting any project. Follow all safety precautions. Information in this document has been furnished by the National Retail Hardware Association (NRHA) and associated contributors. Every effort has been made to ensure accuracy and safety. Neither NRHA, any contributor, nor the retailer can be held responsible for damages or injuries resulting from the use of the information in this document.

How Insulating Your Home Saves Money

Heating and cooling your home accounts for about 50-70 percent of your home energy use. Unless it was built as an energy-efficient home, adding insulation will likely reduce your utility bills. Even a small amount of insulation, if properly installed, can reduce energy costs dramatically.

Insulation Areas

You should insulate all areas of your home. Insulation priorities include your attic, under floors above unheated basements or crawl spaces, and on the edges of concrete slabs. Your options for insulating existing walls are somewhat limited. However, if you are remodeling or residing your home, use the amounts of insulation recommended for new construction. Savings from wall insulation are almost equal to those you'll get from ceiling insulation.

diagram of house insulation

The illustration above shows you where to insulate and also contains the range of recommended R-values for each of those areas in your house. The recommended R-value changes with the type of heat you use and where you live. It also changes between new and existing homes. To find the recommended R-value for your area, contact your local electric or gas company. You can also find the recommended R-value by inserting your zip code and heat source at the Department of Energy Web site.

Insulation Amount

Note that the greatest energy savings come from the first inch of insulation installed. You can add more insulation to increase your savings, but a small amount of insulation is nearly a must for a comfortable home. Also keep in mind that for insulation to work properly, the air spaces in the insulation must be maintained. Packing too much insulation into an area will reduce the effectiveness of the insulation.

Plugging Air Leaks

You can further increase your energy savings, up to 10 percent, by plugging any air leaks prior to insulating. Obvious air leaks can be found around doors, windows, fireplaces and chimneys. Some not-so-obvious air leaks can be found around electrical switches and outlets, pull-down attic stairs, pipes, and behind bathtub and shower stall units.

Types of Insulation Materials

Warning: With any of these insulation materials and installation methods, you should wear a protective face mask to avoid breathing in material dust. Depending on the material you work with, you may also want to wear gloves or safety glasses.

Most insulating materials are available in several common forms: loose-fill or spray-applied materials, blanket rolls, batts, boards and foil-faced paper, foam, film, and cardboard. Each form is ideal for specific insulating jobs. The type of insulation material you select for any job depends on how you intend to use it, how much you want to spend, and how easy it is to install. For more insulation material options, you may want to check out green insulation options, too.

Consider the advantages, disadvantages, and instructions for using each type of material as outlined below before starting.

Blankets and Batts

Blanket and batt insulation is usually made from fiberglass or rock wool. It comes both “faced” and “unfaced.” “Faced” means the batt or blanket has a cover such as paper or foil on one side, while “unfaced” means there is no cover. Some batts and blankets now come with a protective covering that reduces the "itchy feeling" you get when you work with insulation.

General Installation Method

This method is installed by being fitted between studs, joists, and beams.

Where Applicable

Blankets and batts are applicable in all unfinished walls, floors, and ceilings.


This option is for great for someone who wants to install insulation themselves, as it is easy to use and manage.

Rigid Foam

Rigid foam insulation is widely used on basement and exterior walls. Note that when using a foil-covered rigid foam, the foil must be away from the heated side of the wall to avoid condensation problems.

General Installation Method

For interior applications, it must be covered with 1/2 inch of gypsum board or other building-code approved material for fire safety. For exterior applications, it must be covered with weatherproof facing.

Where Applicable

It can be installed in basement walls, exterior walls under finishing, and unvented low-slope roofs.


This product has a high insulation value for relatively little thickness and can block thermal short circuits when installed continuously over frames or joists.

Loose-Fill or Spray-applied

This insulation method is usually made from rock wool, fiberglass, cellulose, or polyurethane foam.

General Installation Method

Loose-Fill or spray-applied is either blown into place or sprayed with special equipment. Check the "Spreading Loose-Fill Insulation Materials" part below for more information.

Where Applicable

It is applicable in enclosed, existing wall cavities; open, new wall cavities; unfinished attic floors, and hard-to-reach places.


It is commonly used for insulation for retrofits, or adding insulation to existing finished areas, and it works great for irregularly shaped areas and around obstructions.

Reflective Systems

Reflective systems come in a variety of types, including foil-faced paper, polyethylene bubbles, plastic film, and cardboard.

General Installation Method

Foils, films, and papers are to be fitted between wood-frame studs, joists, and beams.

Where Applicable

You can use this method for unfinished ceilings, walls, and floors.


This DIY option is suitable for framing at standard spacing and bubble-form if framing is irregular or if obstructions are present. Its effectiveness depends on the spacing and heat-flow direction.

Spreading Loose-Fill Insulation Materials

Step 1 – Make a Rake

Loose-fill insulating materials made of rock wool, fiberglass, or cellulose are commonly used for insulating attics. Vermiculite is not currently used for homes, but it may be found in older homes. It is best to install these materials with a plywood rake attached to a rake handle, making spreading easier.

Warning: “Make sure you wear a dust mask when installing insulation. Wear long sleeves and gloves. Use duct tape around your wrists so you don’t let the insulation up your sleeves,” our HVAC/plumbing consultant Wayne McCarthy suggests.

installing attic insulationdiagram of insulation

Step 2 – Decide on Depth, Then Spread

Next, decide how deep you plan to install the loose-fill material. For example, suppose you are planning to lay the loose-fill material to a depth of 3 inches between the attic joists. Measure the depth in the space you plan to fill and then saw the plywood rake as illustrated above. The rake should ride on the joist on either side and level the material off evenly to a depth of 3 inches. Attach a handle, making a handy tool that will save you hours of backbreaking labor and enable you to rake the material easily and evenly into otherwise unreachable corners.

Installing Blanket Insulation

installing blanket insulation

Always apply blanket-type insulation with the vapor barrier facing the interior of your home; the vapor barrier should always be toward the source of heat in the winter. Never place a vapor barrier between two layers of insulation. This can lead to condensation problems and reduce the effectiveness of the insulation.

Lay the blanket as close to the joists and floor as possible. Then, fill any gaps with loose-fill insulation or place another layer of blanket insulation across the previous layer.

Pipes and Ducts

Place insulation on the outside of pipes or ducts. This means the insulation should be between the outside wall and the pipes.

Attic Joists

Staple blanket insulation when laid between joists in the attic. Most rolls of blanket insulation materials have flanges that can be stapled or tacked to the ceiling joists. Always keep the blanket as close to the joists and floor area as possible. Fill any gaps with strips of insulation or loose-fill insulation.

Proper ventilation in the attic is important in any insulation job. Make provision for air to flow in and around the eave vents and to flow out through a ridge vent roof ventilator or through a ventilator on the end of the house. Never allow blanket-type insulation to cut off the flow of air and stop proper ventilation in an attic.

Ceiling Joists

Blanket insulation without a vapor barrier can be wedged between existing ceiling joists. Make sure the insulation comes to the top of the plate to avoid heat loss from the penetration of wind under the insulation. Failure to pay close attention to this detail can lead to a frost line forming on cold, windy days.

Roofing and Rafters

There are special-formed inserts made of foam or plastic designed to go up next to the roof between the rafters. They help with both the airflow and the frost line. Many of them are designed to be installed during new construction, but they can be installed in an existing roof with little extra effort. In some cases, it may be easier to apply the blanket between the rafters on the roof. In this case, staple the blanket insulation directly to the rafters.

diagram of roof and rafter

Whether you apply the insulation to the attic roof or the floor, always double it back at the end for maximum efficiency. The illustration B shows how the same material can be doubled back between the rafters of the roof.

Insulating Walls

When building a new structure, insulate the full wall, including around the openings for doors and windows.

Step 1 – Lay Blanket Material

If possible, lay blanket-type insulating material between the studs in the wall. If you're using insulation blankets without a vapor barrier, they should be forced into the area between the studs.

Step 2 – Install Polyethylene Vapor Barrier

insulating walls

Then, place a polyethylene vapor barrier on the inside face of the wall. Staple the vapor barrier into place. Use drywall with a foil back as a vapor barrier instead of polyethylene if it is more practical.

Step 3 – Install Blanket Insulation

Blanket insulation material with a vapor barrier attached can be stapled into position. When the blanket has a vapor barrier, take the time to staple or tack all sides, bottoms and tops. This increases the efficiency of the insulation.

Use scraps of insulation material to insulate all the cracks and crevices around doors and windows. Then use scraps of vapor barrier to seal these areas. Staple the barrier in place.

Tip: “Using expanding foam insulation is better around the gaps around window and door frames. You can buy it at hardware stores in aerosol cans, and you can trim the excess as needed,” our HVAC/plumbing consultant Wayne McCarthy says.

It takes few special skills or tools to install insulation. Just invest some time and you can increase the efficiency of your home and decrease the total on your bills.

Calculating Necessary Insulation

For a new home, find out what the recommended R-value is for the type of heat you are planning to use for the location. Again, local electric and gas companies can provide this information to you or you can contact the Department of Energy.

Step 1 – Identify Current Insulation

For an existing home, it is a little more complicated. First, you need to identify what type of insulation is currently in your home. It may differ by the various locations in your home. In your attic, for example, you may find batt or blanket fiberglass over the top of loose-fill cellulose. You may also find multiple layers of batt or blanket insulation.

Step 2 – Measure Insulation Thickness

Next, you need to measure the thickness of each of these different types of insulation at the different locations. To help you with this process, take a regular sheet of notebook paper and make four columns. Label the first column "Location," the second column "Type Of Insulation," the third column "Inches Thick," and the fourth column "R-Value per Inch."


Insulation Type

R-Value per inch
of thickness

Fiberglass blanket or batt


High-performance fiberglass blanket or batt


Loose-fill fiber glass


Loose-fill rock wool


Loose-fill cellulose


Perlite or vermiculite


Expanded polystyrene board


Extruded polystyrene board


Polyisocyanurate board, unfaced


Polyisocyanurate board, foil-faced


Spray polyurethane foam


Step 3 – Find the R-Value

The chart above shows you the approximate R-value each inch of the various types of insulating materials provides. Use this chart to fill in the last column of your worksheet. One inch of fiberglass batts or blankets, for example, provides an approximate R-value of 3.2. To find the R-value of 4 inches of fiberglass, multiply 4 x 3.2 to get an R-value of 12.8. Repeat this process for each area in your home. If you have two different types of insulation together, find the R-value for each and then add them together.