Building envelope: Insulation

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A warm and cozy home is a well insulated home

Insulation helps keep outdoor air from getting inside your home. It also prevents indoor air from escaping. It works by trapping pockets of air and slowing down the in/out process. For optimal energy efficiency, your home should be properly insulated from the roof down to its foundation.

Attic insulation

Air leaks in your attic will cause substantial heat loss and lead to a variety of moisture-related problems in your home. For maximum energy efficiency, attics should be sealed, insulated, and ventilated.

What to look for

  • Insulation is rated by its R-value. R stands for resistance and the higher the R-value, the more efficiently it resists the transfer of heat from one area to another.
  • Different types of insulation have different R-values, but you can combine them to achieve a higher overall rating.
  • The recommended R-value for attic insulation in Ontario is between R-50 to R-60.
  • The most common types of insulation used in attics are spray form, loose-fill, and batt and blanket insulation.

Things to consider

  • Ensure your project meets the minimum R-Value needed to receive available rebates.
  • Hire a professional. Improper installation can lower the R-value of the material, and there are health and safety measures that must be considered.

Average cost

$1.50 to $3.50/sq. ft.

Source: Natural Resources Canada

Wall insulation

Walls can account for up to 20% of heat loss in your home. In addition to heat loss through your walls, cracks and penetrations may allow uncontrolled air leakage into and out of your home.

The type of insulation you need will depend on the type of walls (i.e. solid, concrete block, frame) in your home. You can install one or more of the following: blown-in, rigid board, batt/blanket and spray foam insulation.

What to look for

  • Insulation is rated by its R-value. R is the resistance and the higher an insulation's R-value, the more efficiently it resists the transfer of heat from one area to another.
  • Different types of insulation have different R-values. You can use more than one type to achieve a higher overall R-value rating.

Things to consider

  • Cold floors and walls in the winter and mould growth are signs of a poorly insulated home.
  • Ensure your project meets the minimum R-value required to be eligible for rebates, if available.
  • Hire a professional. Improper installation can lower the R-value of the material, and there are health and safety considerations as well.

Average cost

$150 to $3,000, plus installation.

Source: Natural Resources Canada

Basement insulation

A basement can account for about 20% of a home's total heat loss. Adding insulation to your basement is important whether or not space will be finished.

Much like your attic, basements need to be sealed, insulated, and ventilated. Proper insulation not only reduces heating and cooling costs but also improves comfort. The materials used to insulate your basement will depend on your foundation and whether you need to insulate inside or outside of your home.

What to look for

  • Insulation is rated by its R-value. R is the resistance and the higher an insulation's R-value, the more efficiently it resists the transfer of heat from one area to another. Different types of insulation have different R-values, and they can be combined to achieve a higher overall R-value rating.
  • The goal is to achieve a minimum of R12 for 100% basement.

Things to consider

  • Before planning your renovation, assess your basement. Check for water leaks, dampness and determine if you need interior or exterior insulation.
  • Do not insulate the interior of a basement with leaks or dampness problems.
  • Ensure your project meets the minimum R-value needed to receive any available rebates.

Average cost

$6,500 to $18,000

Source: Natural Resources Canada