Roof Insulation 101: How It Works and What Choices You Have

an attic's roof insulation

Installing an insulating layer in your home is crucial for many reasons. Insulation helps you use less electricity and gas on heating and cooling your house, saving you money and reducing your energy footprint. It also ensures that your home is kept at a comfortable temperature for you to live in.

But looking at the different types of insulation available can be confusing. It can be hard to learn what kind of insulation is best for you, and how much of it you need. Some homes already have insulation, but need more for optimal results and efficiency.

What Types of Roof Insulation Are Available?

a spray foam insulation close-up

There are three main types of insulation. There are fiberglass, cellulose, and foam types. All of them are composed of different materials and look different in form. However, they are all created to do the same thing: keep your house insulated.

Fiberglass usually comes in batts or rolls. However, it does sometimes come in a loose form which can be blown into your attic. The batts or rolls are typically installed on either the attic floor or ceiling. Wherever the insulation meets with duct work, electrical outlets, or other obstructions pieces are cut out to make it fit properly.

Cellulose insulation is made up of recycled materials such as newspapers. These materials are shredded into tiny pieces. After that, they’re coated in a fire retardant to keep them from becoming a fire hazard. During installation, this type of insulation is blown into place, and the tiny pieces form a dense, thick layer which insulates the house it covers.

The last type is foam insulation. This variety has to be installed professionally. It is sprayed into the house and comes in two types. Open cell foam insulation mainly works as an air barrier, while the closed cell type also blocks vapors and moisture.

Pros and Cons of Roof Insulation Varieties

Spray Foam Insulation

  • Pro: Has a high level of efficiency, with an R-value which is much higher than what is found in other types. The closed cell variety has an R-value of up to 7 per inch, while, the open cell form is about half that value.
  • Pro: A long lifespan ensures that you won’t have to replace this anytime soon. Foam insulation can last up to 80 years, which means you’ll get a full lifetime of use out of it.
  • Pro: Works well in both hot and cold weather. Instead of letting hot air escape through your roof when it’s chilly outside, this helps your house retain warmth in the winter and stay cool in the summer.
  • Con: Costs more to purchase and have installed. The price per square foot is substantially more than the price per square foot of most types of fiberglass.
  • Con: Spray foam insulation is flammable. However, most closed cell types come with a fire retardant.

Cellulose Insulation

  • Pro: Made from recycled materials. This insulator is made up of finely shredded paper fibers. By using them to insulate your house, you’ll be giving new life to old newspapers, boxes, and similar items.
  • Pro: This blown in insulation acts as a fire barrier. Because the papers have been treated with a flame retardant, they are actually classified as a fire blocking material.
  • Pro: Cellulose is affordable and has a low cost per square foot.
  • Con: Susceptible to the wind. If your roof isn’t properly sealed and has strong drafts, it’s possible for gusts of wind to shift loosely blown cellulose. This can result in uneven coverage.
  • Con: A special blower is required for installing this in place.

Fiberglass Insulation

  • Pro: Fiberglass is cheap and relatively easy to install, and unless you choose a loose type it doesn’t require any special equipment.
  • Pro: Fiberglass isn’t flammable. However, it is wise to note that the Kraft backing on many batts is indeed flammable.
  • Con: Fiberglass can settle over time, which leads to a reduction of its R-value.
  • Con: Fiberglass doesn’t block air flow very well, which can result in compromised performance. This is especially true during cold, wintry days.

How Does Roof Insulation Work?

a female workers putting up a roof insulation

According to Energy Star, “The attic is usually where you can find some of the largest opportunities to save energy in your home.”

Insulation works by creating a buffer between your living space and the extreme temperatures outside. This keeps heat and cold from passing right through your walls.

The R-value refers to the insulator’s ability to resist heat loss. Higher R-values represent better efficiency. The amount your house needs varies depending on the typical climate of the area where you live.

Installing this insulating barrier can be done by homeowners when fiberglass and cellulose are involved. However, it’s wise to seek professional help if your attic is difficult to navigate or if you suspect any water or rot damage in your attic. You’ll also want to do your research regarding installation techniques and methods, and remember to wear protective clothing and a mask to protect your lungs.

Bottom Line

Adding an insulating layer to your attic helps keep heat from pouring into your roof during the summer. During the winter, it helps you keep warmth inside of your house. Your home appliances don’t have to work as hard to keep you comfortable. This, in turn, saves you money and keeps you from needing to sacrifice comfort to save energy.

If you’re building a new house, it’s important to get it insulated well right from the start. For existing homeowners, adding additional materials to meet Energy Star recommendations can result in a significant increase in comfort and energy efficiency.

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