How Much Does Attic Insulation Cost?

By Geoffrey Sperring

July 08, 2025

You're frustrated by high energy bills. In winter, the furnace seems to run constantly to keep a comfortable temperature in your home, and in summer, you run the air conditioner most of the time. If this sounds familiar, it's time to improve the insulation in your attic. In the average home, up to 25% of heating energy is lost via heat transfer through the ceilings into a poorly insulated or uninsulated attic.

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When you balance these energy losses against an average attic insulation cost of $2,500 (CAD 3,445), you can see how the upgrade can pay for itself within a few years.

What Is Insulation?

Insulation reduces the transfer of energy from one side of the material to the other, reducing heat loss or gain. Energy can be transferred by conduction, convection and radiation. Insulation is a poor heat conductor and contains tiny pockets of trapped air or gas to reduce convection. A layer of aluminum foil or other reflective material is used to limit radiant heat transfer.

Why Should You Insulate Your Attic?

Your home's roof is constantly exposed to cold air, ice or snow in winter and the sun's heat in summer. Because of this, the attic space below gets cold in winter and hot in summer. Often, unfinished attics have little insulation compared to a home's living areas, and heat naturally rises, so energy transfer can easily occur in this space. By insulating the attic, you can significantly reduce energy transfer and heat loss so finished areas of the home stay warmer in winter and cooler in summer.

What Are the Different Insulation Materials?

When comparing insulation products, it's important to consider the material and its insulating properties and the type or form of insulation. The most important characteristic of insulation is its R-value, which is a measure of the material's thermal resistance or ability to block heat flow.

The higher the R-value, the better a material's insulating quality. R-values are cumulative, so if you double the thickness of an insulation, the R-value doubles as well. Common insulation materials are fiberglass, cellulose, rock/mineral wool, polyurethane and reflective aluminum foil.

Fiberglass Insulation

Fiberglass insulation is made from extremely thin glass fibers that trap air, increasing thermal resistance. According to HomeGuide, it has an R-value of 2.2 to 2.9 per inch of thickness. It's popular because of its ease of use and low price of $0.30 to $1.30 (CAD 0.41 to CAD 1.79) per square foot.

Cellulose Insulation

Made from recycled paper processed into fibers, cellulose insulation is used with both blown-in and loose fill installation methods. Adding boric acid during manufacturing provides fire and insect resistance. Cellulose has a good R-value of between 3.1 and 3.8. The only drawback is it deteriorates with age and should be replaced after 20 to 30 years. The cost per square foot of 1-inch-thick cellulose is between $1.20 and $2.50 (CAD 1.65 and CAD 3.44).

Rock/Mineral Wool

Rock or mineral wool is made by melting basalt rock and blast-furnace slag and spinning the molten material into fibers. It's fireproof, inert, insect-resistant and durable, with an R-value of 3.2 to 4.1. The cost varies from $0.30 to $1.80 (CAD 0.41 to CAD 2.48) per square foot.

Open-Cell Spray Polyurethane Foam

Open-cell foam is a low-density polyurethane material that expands to fill cavities. It has an R-value of 3.5 to 3.7 per inch of thickness, and the insulation spray foam costs between $0.30 and $0.50 (CAD 0.41 and CAD 0.69) per square foot at 1 inch thick.

Closed-Cell Spray Polyurethane Foam

This dense polyurethane foam is blown in using an inert gas. It has a high R-value of 5.0 to 7.0 per inch. The cost ranges between $0.90 and $1 (CAD 1.24 and CAD 1.38) per square foot of 1-inch-thick foam.

Reflective Foil Insulation

Reflective insulation comes in rolls or sheets and consists of a foil radiant barrier backed by a thin layer of thermal insulation. Although it has a low R-value of 1.3 to 1.6 per inch, its distinguishing feature is its ability to reflect radiant heat. Reflective insulation costs between $0.30 and $0.80 (CAD 0.41 and CAD 1.10) per square foot.

Insulation Types

Attic insulation comes in several forms, including:

Batts. These precut pieces of insulation are sized to fit between standard ceiling joists. Batts come in different thicknesses and may be made from fiberglass or rock/mineral wool.
Rolls or sheets. Fiberglass insulation may be available in wide rolls and cut to size on site. Reflective foil may be available in sheets or rolls.
Blown-in. Made from cellulose, fiberglass or mineral wool, blown-in insulation consists of small particles that are installed using an insulation blowing machine.
Foam. Polyurethane foam is formed by combining two liquid chemicals and mixed on-site using specialized equipment. It expands rapidly and sets within a few minutes.

How Much Insulation Is Needed for My Attic?

The amount of insulation needed depends on your location. The United States is divided into climate zones that are assigned a number between 1 (warm) and 8 (extremely cold). Each zone has a recommended R-value for insulating attics.

In Zone 1, the minimum recommended attic insulation R-value is R-30. In Zones 2 and 3, that value is R-49. In Zones 4 through 8, the minimum recommended value is R-60.

Average Home Attic Insulation Costs

According to HomeGuide, the average cost to insulate an attic ranges from $1 to $4 (CAD 1.38 to CAD 5.51) per square foot. Depending on the square footage of the space, the total cost can range from $500 to $7,000 (CAD 689 to $9,645). The average cost homeowners pay falls between $1,000 and $2,700 (CAD 1,378 and CAD 3,720).

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Attic Insulation Costs — by Type

The following table provides a breakdown of installed costs for different types of attic insulation.

Batt or Roll Insulation

Batt or roll insulation is probably what you think of when you think of insulation — that pink fiberglass stuff that comes in huge rolls. This is the most common form of insulation, coming in at 80 cents to $2.60 (CAD 1.10 to CAD 3.58) per square foot.

Blow-In Insulation

"Blow-in" or "blown-in" insulation is installed with a machine that "blows in" fluffy insulation material. The benefit is that you can fill in cavities in attics with the loose material. It's also called "loose-fill" insulation for that reason. Blown-in insulation costsbetween 90 cents and $2.40 (CAD 1.24 and CAD 3.31) per square foot.

Spray Foam Insulation

Spray foam insulation is made of plastic, and it expands to fill whatever space you spray it in. There are two types, closed- and open-cell. Closed-cell is often waterproof, and it has a much more rigid structure. Open-cell is softer and allows for more moisture and air to move through. Expect to pay between $1 and $4.50 (CAD 1.38 and CAD 6.20) per square foot for spray foam insulation.

Reflective Insulation

Reflective insulation employs the same technology as those aluminum foil-looking emergency blankets. The different layers reflect and trap radiant heat, keeping your attic warm in the winter and cool in the summer. Reflective insulation can be the cheapest type of insulation, costing between 50 cents and $2.20 (CAD 0.69 and CAD 3.03) per square foot.

Cost Factors to Consider

Besides the price of insulation, several other factors may affect the overall cost to insulate your attic:

Labor charges. Installation typically costs between $0.50 and $1.30 (CAD 0.69 and CAD 1.79) per square foot. But if you have the skills and agility, you may be able to install attic insulation yourself.
Home age. Older homes require more preparation work, such as sealing air leaks and making needed repairs.
Accessibility. Some places may be hard to reach, especially in homes with low-pitched roofs.
Pest removal. It's best to get the attic inspected for pests in case removal or treatment is needed before insulating.
Air sealing. It's essential to air seal the attic before installing insulation to prevent energy loss through gaps and cracks.
Ventilation. It may be necessary to add roof ventilation to minimize heat and moisture retention in the attic. This can cost between $200 and $700 (CAD 276 and CAD 965) per roof vent.

How Much Does It Cost to Remove and Replace Attic Insulation?

If you have old attic insulation in place, it may be possible to lay new insulation on top, provided the existing insulation is in good condition. It's important to note that certain types of insulation degrade over time. Also, exposure to moisture reduces the performance of cellulose and mineral wool insulation and can cause mold growth. Other potential concerns with old insulation are rodent nests, contamination from animal droppings and whether the material contains asbestos.

In most instances, it's better to completely remove any old insulation before putting new material in place. This offers the opportunity to make necessary repairs and seal gaps and cracks before installing the new material. Replacing old insulation costs $2 to $6 (CAD 2.76 to CAD 8.27) per square foot, which includes $1 to $2 (CAD 1.38 to CAD 2.76) per square foot for removing existing insulation.

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