According to the City of Ottawa, the minimum R-value for attic insulation is R50. However, different homes will require different amounts of insulation depending on various factors, such as the age and type of home, the heated area of the house, and the climate.

In this blog post, we’ll break down some of the critical factors that impact how much insulation you need in your attic so that you can make an informed decision about how to best insulate your home.

3 Important Factors  Determining How Much Insulation is Needed in an Attic:

The following three factors determine how much insulation you need in your attic, so while insulating your attic, keep these in careful mind:

Factor # 1: Age and Type of Home

One of the key factors that will impact how much insulation you need in your attic is the age and type of home. Older homes tend to have less insulation because they were built before current energy efficiency standards came into effect. As a result, you may need to add more insulation to an older home to achieve the same level of energy efficiency as a newer home.

The type of home also matters when it comes to determining how much insulation you need. For example, homes with cathedral ceilings will require more insulation than a standard eight-foot ceiling because there is more air space to heat or cool.

Factor # 2: Heated Area of Home

Another factor that will affect how much insulation you need is the heated area of your home. This refers to the percentage of your home that is heated by your furnace or another heating source. The larger the heated area, the more insulation you will need because there is more space to heat or cool.

For example, if your home has 2,000 square feet of living space but only 1,000 square feet are heated by your furnace, then you only need enough insulation to cover 1,000 square feet.

You can calculate the heated area of your home by subtracting any unheated areas from the total square footage of your home. Unheated areas can include unfinished attics, unfinished basements, and garage spaces.

Factor # 3: Climate

The climate you live in will also play a role in how much attic insulation you need. In general, homes in cold climates require more insulation than homes in warm climates because there is a greater difference between indoor and outdoor temperatures. As a result, more heat is lost through ceilings and walls in a cold climate than in a warm climate.


Determining how much attic insulation you need is not an exact science since several factors come into play including the age and type of home as well as the size of the heated area and climate. However, by considering these factors, you can get a better idea of how much attic insulation you need to keep your home comfortable all year round while also saving money on your energy bills.

Are you interested in learning more? Get your free insulation estimate here.

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