Insulate Your Home

How to stop the great escape!

From the very moment heat is generated inside your home, it tries to escape to the colder outdoors. Over and above air leakage, heat is also lost through the ceiling, basement, windows and doors, and walls by conduction, convection, and radiation.

The rate of heat loss depends on the difference between inside and outside temperatures and the insulation resistance met by escaping heat. Increasing the insulation in these areas reduces the heat loss.

Does your home need extra insulation?
If snow is melting on your roof on a cold, dull winter day, you likely don’t have enough insulation in the attic. If snow is disappearing from around the sides of your house, you probably need more insulation on the basement walls. Sometimes it may be obvious where you need insulation; other times it may be difficult to determine the best locations to add insulation.

To determine payback on your investment you must consider the ease of doing the job and the cost of materials. However, if comfort is your priority, upgrade insulation in your home in any order – as long as air sealing is done first. Air sealing will achieve the fastest payback and will help to protect the wood framing and insulation from moisture damage. Refer to Section 10 to request more information when considering adding insulation.

Laying rugs on cold floors in your home (rooms above unheated spaces like garages and crawlspaces) will help to make the floor feel warmer.

R-value: The measure of insulation
Insulation is measured based on its heat loss resistance: R-value for short (RSI-value in metric). A higher R value number indicates a more effective level of insulation. As insulation is made from different materials, there are varying R-values for the same thickness. To check the insulation levels of exterior walls, turn the power off and remove the cover of an electrical outlet. If there is a gap, you may be able to see the insulation. Push a thin wooden stick between the electrical box and the drywall or plaster to the back of the wall and measure the depth. In the attic, slide a ruler down the side of a floor joist and measure the depth of insulation.

TIP: To determine the approximate R-value of batt or loose fill insulation, multiply the depth (in inches) by 3. For example, 4 inches x 3 = R-12

Approximate R-value = Depth of insulation in inches x 3 The recommended R-value of insulation may vary depending on where you live. Check with your local Building Department for current required levels. The amount of insulation you can add may also depend on how much physical space is available in the walls or attic.

Heat Loss Graphic

TIP: When adding insulation, consider the ease of doing the job, the cost of materials, and the increased comfort level.

Note: Every house is different. The size, age, type of house and the work the homeowner has already completed, all influence the energy-saving potential, percentage of heat loss and priorities of work to do in the house. This illustration indicates typical heat losses.

The following priority list will assist you in determining where your energy dollars and efforts are best spent when adding insulation:

TIP: Air seal all penetrations before adding insulation.


1. The attic
Though it has a relatively low heat loss, 10 – 15%, the attic is the first place to consider adding more insulation. It is generally the easiest and least expensive area to insulate. It is especially important to add more insulation if there is less than 10 inches (approximately R-30).


2. The basement
Since an unfinished basement has a high heat loss, 20 – 25%, adding exterior or interior insulation is a major opportunity to improve your home’s thermal efficiency. Basement insulation is most cost-effective when done in conjunction with finishing the basement as living space, or when digging up the exterior to repair foundation wall drainage. While renovating, if you enclose a natural gas or oil furnace and a natural gas water heater, you must allow for combustion air supply to the equipment. The air supply may be from outside, or in some cases, from inside your house. A trained heating/ventilation contractor can help you determine the combustion air requirements for your natural gas equipment.

Windows and Doors

3. The windows and doors
Windows and doors represent about 15 – 20% of your home’s heat loss.
Remember, this is the heat loss through the glass, wood, and framing materials;
not heat loss from air leakage. Depending on the age, operation, and design of your
windows and doors, you may want to consider replacing them. Consider replacing
windows and doors if they do not operate easily, are in poor condition, or are
difficult to weatherstrip.


4. The walls
Adding insulation to walls is worthwhile if done in coordination with renovating
the interior walls or re-siding - this can reduce heat loss by 10 – 20%.

Protecting the insulation with air and vapour barriers
To be effective and to minimize moisture damage, you must protect insulation with both an air and vapour barrier. In the winter, the air that leaves your home is warm and moisture-laden. When this moisture meets cold surfaces in the walls and attic, it will condense and can then be absorbed by the wood framing and insulation. If insulation becomes too wet, its ability to resist heat loss is diminished. There are numerous ways to create effective air/vapour barriers.

Air barriers
Air barriers prevent indoor air, which is carrying moisture, from exiting through cracks. Air barriers also prevent wind from whistling through the insulation. Some insulation, such as glass fibre, rock wool, and cellulose, can resist heat loss by trapping small pockets of air. The greater the number of undisturbed air pockets, the higher theR-value. If wind can blow through this insulation, its ability to resist heat loss is greatly reduced.

There are a number of ways you can create an air barrier that will protect the insulation from wind and moisture. Caulking and weatherstripping installed on the indoor cracks and leaks will prevent air and moisture from entering or exiting the house. In new construction, specially designed materials are wrapped around the outside of the house behind the siding or brick. This material resists wind, but still allows any moisture that gets in the wall to diffuse through. Air barriers are very important! In fact, studies indicate that an air barrier is 100 times more effective than a vapour barrier at stopping moisture from getting into a wall or attic.

Vapour barriers
Vapour barriers stop moisture traveling directly through a material, like drywall, by diffusion. They are usually constructed of 6 mil polyethylene and installed on the warm side of insulation(normally right behind the drywall).

Vapour barriers improve as a house gets older because each coat of paint and some wallpapers help resist moisture traveling through the drywall or plaster. To make the vapour barrier most effective, the 6 mil polyethylene needs to be sealed at every seam with acoustical caulking (a tar-like caulking) or taped with red contractor’s tape. Together, the polyethylene and the caulking/tape form an air/vapour barrier.

Reducing window heat loss
Here are some tips to improve your window’s insulating value:

• Heavy drapes or energy-efficient window coverings can be used to reduce heat loss, especially at night. During cold winter days, be sure to open your drapes to allow heat and air circulation to get to the glass to help minimize condensation problems. And in the summer, block the hot sun by closing your drapes during the day.

• Improve the thermal resistance of the existing window glazing by installing additional layers of glazing. This can be done by adding either an exterior storm window or an ‘interior storm window’. Interior storm
windows are made of either acrylic sheet attached to the window trim with a magnetic seal, or thin sheets of polyethylene that are attached with double-sided tape. A hair dryer is used to ‘shrink’ the plastic in place and to ensure it is installed airtight. Both are available commercially.

Some tips for purchasing new windows:
To identify energy-efficient windows, skylights and sliding glass doors look for the ENERGY STAR® label. The label indicates which climate zone(s) the product qualifies for. Four climate zones have been designated across Canada, the more zones a product qualifies for, the more energy efficient it is. ENERGY STAR information is also in the product literature for each model. ENERGY STAR qualified windows will reduce your energy costs up to 12%.


ENERGY STAR® qualified windows, skylights and sliding glass doors will have many of the following features:

• double or triple glazing with sealed insulating glass unit.
• low-emissivity (low-e) glass.
• inert gas, such as argon or krypton, in the sealed unit.
• low conductivity or 'warm edge' spacer bars.
• insulated frames and sashes.
• superior air-tightness.

To minimize heat loss, windows must be insulated and air sealed at the frame-to-wall joint when installed. You need to confirm this procedure with the contractor prior to and during the installation.

To ensure a quality installation of your new windows, choose a contractor who has been trained and certified by Window Wise. Window Wise is a quality assurance program that independently audits and certifies contractors and window manufacturers, and conducts comprehensive window installation training for installers. Look for the Window Wise logo and be protected by an industry-backed guarantee. For more information on Window Wise and to find certified companies, visit