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Cost to Insulate Attic

Whether you live in a warm or a cold climate, keeping your house a comfortable temperature is not an inexpensive task. While you can keep your hands off the thermostat and sweat in the summer and freeze in the winter, there is a more comfortable solution to keeping your heating and cooling costs in check.

A properly insulated attic is one project where the savings add up every year. In fact, the U.S. Department of Energy says that attic insulation can take anywhere from 10% to 50% off your heating bill and help stabilize your house's indoor temperature in the summer. If these saving sound good to you, let ImproveNet help you connect with a local attic insulation professional.

Table of Contents

  1. Attic Installation Costs
  2. Different Types of Attic Insulation
    1. Spray Foam Insulation
    2. Rolled or Blanket Insulation
    3. Loose Fill Insulation
    4. Alternative Insulation Materials
  3. Labor Costs Associated With Installing Attic Insulation
  4. Extra Costs to Consider
  5. The Cost Benefits of Attic Insulation
  6. What is R-Value?
  7. Find A Pro

Attic Insulation Costs

  • Minimum cost of attic insulation: $1,700
  • Average cost of attic insulation: $1,900
  • Maximum cost of attic insulation: $2,100

Different Types of Attic Insulation

Like other materials in your home, insulation wears down over time. How do you know when you need more insulation in your attic? A simple test is to look across the attic floor and see where the insulation sits in relation to the floor joists. If you can't see the joists because the insulation is above them, then it is still in good shape. However, if you can see the floor joists sticking up above the insulation, it's time to either replace the insulation or add more.

There are many different types of insulation from which to choose. When you're trying to decide on the best option for your attic, you need to keep in mind the amount of money you're willing to spend, the R-value you need (dependent on where you live), and the type of obstructions in your attic.

Attic Installation Costs

Spray Foam Insulation

Spray foam insulation is the most expensive type of insulation. It is available in two forms: open cell and closed cell. Open cell spray foam is the less expensive option. However, one disadvantage of open cell spray foam is that it doesn't offer any vapor barrier. On the other hand, while closed cell spray foam insulation is more expensive, it is also denser and offers a good barrier against water and air.

Additionally, spray foam insulation sticks to any surface where it's sprayed. Therefore, an installer can apply spray foam insulation to the walls, floors and ceiling for maximum protection. However, spray foam cannot be added over existing insulation, so any old insulation will need to be cleared out beforehand. This is why spray foam insulation is a good choice for new construction homes. It's also useful when insulating against noise is a concern. Plus, if you plan on turning your attic into a finished room, spray foam insulation is the best type to use. It costs around $2,208 to install.

R-value per inch:

  • 5 and 6 

Rolled or Blanket Insulation

Rolled or blanket insulation -- also known as batt insulation -- consists of long rolls of insulation fibers. These rolls are held together with either a reflective foil backing or paper. While blanket insulation comes in a variety of thicknesses, the standard width is either 16” or 24”. Blanket insulation fibers are typically made of cellulose, fiberglass or mineral wool. Sometimes, the fibers are even made from recycled blue jeans.

Blanket insulation is ideal for large spaces that would be very expensive to fill with other types of insulation. It's also best for attics in new construction homes that are free of obstructions and attics that have standard spacing between the joists. Blanket insulation can be layered over existing insulation. However, one drawback to this type of insulation is it doesn't fill awkward or tight spaces very well. As a result, the installer will have to cut bits of insulation to the exact shape to fit around areas like electrical junction boxes and framing so there are no leftover voids. The average cost to install blanket insulation runs around $2,091.

R-value per square inch:

  • Cellulose: 3.7 to 3.8
  • Fiberglass: 2.9 to 4.3
  • Mineral wool: 3.0 to 3.3
  • Cotton: 3.7 to 3.8

Loose Fill Insulation

Loose fill insulation contains small chunks of fiberglass, cellulose or mineral wool fiber. It's sold in large bags, and professional installers use blowing machines to install it. Unlike blanket insulation, one main advantage of loose fill insulation is that it's perfect for completely filling in gaps, empty areas and small spaces. Therefore, loose fill insulation is best for attics with obstructions between joists or irregular framing.

Loose fill can also be added over existing insulation. Since it's possible to purchase a bag of loose fill insulation that covers around 40 square feet for less than $12, it typically costs about $1,796 for this type of insulation.

R-value per square inch:

  • Fiberglass: 2.2 to 2.7
  • Cellulose: 3.2 to 3.8
  • Mineral wool: 3.0 to 3.3

Alternative Insulation Materials

Reflective insulation is a shiny layer of aluminum foil that can be added to polyethylene bubble, rigid foam or plastic film insulation. It's designed to block most of the radiant heat that strikes its surface. Due to variations in climate and location where reflective insulation is installed, it is not assigned an R-value. However, it is more effective in spaces less than 3/8 inches wide and works best in confined and small attics. Additionally, reflective insulation is more useful in warmer climates.

Structural insulated panels are layered pieces of hard foam insulation attached to either plywood or oriented strand board. These panels are very strong, inexpensive and energy efficient, and it's possible to cut them to fit just about any type of attic design. Since structural insulated panels are so easy to install, you'll spend less money when hiring a professional to complete the installation. R-values for structural insulated panels vary depending on how thick the panels are and the climate where the panels are installed.

Labor Costs Associated with Installing Attic Insulation

The Department of Energy reports that an attic insulation project can cost anywhere between $1,700 and $2,100 or higher in an average home. In this case, an average home is a two-story structure of around 2,520sf that has an attic with dimensions measuring about 24’ by 50’. Therefore, an attic insulation project will cost approximately $1.50 to $3.50 per square foot.

While it is possible to install some types of insulation on your own, other types require the knowledge and specialized equipment of a professional. In these cases, it's assumed that an average installer will charge around $70 an hour. Additionally, some projects may require the knowledge of an electrician (for instance, if electrical junction boxes need to be moved). The average price of an electrician is between $65 to $85 an hour.

Extra Costs to Consider

As you're preparing for your attic insulation job, there are extra costs associated with getting your attic ready that you need to keep in mind.

  • Seal any air leaks located around your attic. If not, heated or cooled air can easily escape outdoors and make your insulation useless.
    • If you have windows in your attic, you can buy a 16-ounce can of foam sealant for about $6 to seal around the casing.
  • Look around your exhaust fans, pipes, ducts and wires for any gaps. If a gap is less than 1/4 inch wide, you can use a fire-blocking caulk to seal it up. These typically cost $7 for 10 ounces. If the gap is larger than a 1/2 inch, you'll need to use a fire-blocking spray foam, which costs about $10 for 16 ounces.
  • Check flues and chimneys. Here, you'll either need to use metal flashing sealed with high-temperature caulk or furnace cement. High-temperature caulk costs around $8 for 13 ounces, and furnace cement is $12 for half a gallon.
  • Check for moldy or damp spots. Look at joists and existing insulation or for water stains on the roof sheathing to spot any potential leaks. If you find any, they need to be repaired right away.
  • Make sure your light fixtures won't touch any of your insulation. You never want your insulation to come in contact with your light fixtures because it could start a fire. To prevent this from happening, create a safety gap of at least 3 inches around all your light fixtures using metal flashing, plywood or hardware cloth.
  • Ensure all your vents and exhaust fans are directed to the exterior of your house. Even though it's against building code for any kind of exhaust to vent into an attic space, many home builders in the past were able to get away with this shortcut. If your home falls into this category, you'll need to fix this venting issue so humid exhaust air can't get trapped in your insulation and destroy it.

The Cost Benefits of Attic Insulation

In the U.S., the average family spends $1,900 a year on utility bills. Of that figure, nearly 54% goes to heating and cooling the home. Nearly 25% of heat loss in a house occurs through the attic. However, with proper insulation in the attic, you can save more money while heating and cooling your house more efficiently.

In fact, you can save nearly 20% of your energy bill with good attic insulation, and the right type of insulation can cut your heating and cooling costs by over 40%. This means that insulation will pay for itself in around five to six years.

What is R-Value?

Nearly every type of insulation has an R-value. This number measures the resistance to the flow of heat and represents how well the insulation works. When considering the R-value of insulation, remember that the higher the number, the better it insulates per inch of thickness. The minimum R-value recommended for an unfinished attic is based on whether you live in a cold climate or a warm climate. Therefore, colder climates require a higher R-value and warmer climates can get by with a lower R-value.

In general, houses in a cold climate should have a minimum R-value of 49 in the attic. This is equivalent to approximately 16” of fiberglass insulation. On the other hand, houses in warmer climates only need an R-value of 38 or higher. This equals around 12” or more of insulation.

Find A Pro

Given the ample benefits and abundance of options, there is no reason not to install attic insulation. In fact, as we discussed, he can also saved you money in the long run. As such, if you’re ready to update your attic, be sure to review our insulation contractor lead form.

Last updated on Aug 18, 2016

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