The 8 Best Types of Roof Insulation for Your Home

Roof insulation helps keep your home cool in the summer and warm in the winter—and keeps your heaters and AC units from working overtime. If your home lacks proper insulation in the attic, knowing your options could save you money on utility bills and prolong your HVAC system’s lifespan. Read on to learn about eight popular types of roof insulation for your home.

What Is Roof Insulation?

Roof insulation helps protect your home from heat loss and heat gain by padding your roof and preventing heat from traveling in or exiting the house. Installing roofing insulation for your home can play a pivotal role in improving your home’s recommended insulation level or R-value. This value depends on which climate zone you live in, according to Energystar.gov. 

While not all homes require roof insulation—and can get by with just attic insulation—homes with a cathedral ceiling or heavy attic use should have an insulated roof. 

Roof vs. Attic Insulation

Though roof and attic insulation may seem the same, the locations where these two types of insulation are installed differ—so knowing the anatomy of your roof can really come in handy. 

Roof insulation goes above or below the rafters or underneath the roof sheathing, also called roof decking. Roof insulation costs between $2,500 and $8,000, on average.

Attic insulation goes in the ceiling, walls, and rafters of your home. There are also several types of attic insulation to consider. Attic insulation costs less than installing insulation in the roof, coming in at around $1,700 to $2,100 on average. Attic insulation is also easier to install.

Types of Roof Insulation

1. Fiberglass Batts

Fiberglass batts are a popular type of insulation for rafters. They’re budget-friendly—costing around $0.30 to $1.50 per foot—and come in all sorts of shapes and R-Values, making customizing your home’s insulation relatively straightforward. 

One con of choosing fiberglass batts is that the material is bulky and harmful to inhale. 

According to the Washington State Department of Health, inhaling airborne fiberglass dust, or coming into direct contact with fiberglass, can cause irritation of the skin, eyes, nose, throat, and lungs. 

If you inhale high levels of the material, you may experience worsened asthma symptoms or symptoms akin to bronchitis. For this reason, wear disposable coveralls, gloves, a face mask, eye goggles, long-sleeved pants, and a long-sleeved shirt underneath the coverall to protect yourself from stray fiberglass particles.

Another drawback of fiberglass batts is that they can fall out over time, so it’s a good idea to inspect your insulation yearly for signs of fallen insulation.

2. Spray Foam Insulation

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Spray foam insulation is an easy way to reach difficult spaces in your roof, providing a better seal for the roof. This is especially useful for unconventional roofing designs or narrow rafters. You can install spray foam insulation to the underside of your roof deck to improve the R-value. Spray foam insulation controls both thermal heat and water vapor. 

The main downside to spray foam is the cost. You’ll pay anywhere between $0.50 to $2 per foot for spray foam—which is approximately two times more than you would spend on fiberglass batts. It can also be messy and requires an experienced professional to do it correctly.

3. High-Density Polyiso Cover Boards 

High-density polyisocyanurate (polyiso) cover boards are a type of double-layered insulation that serve as a better top surface for roof insulation materials than single-layered insulation. This type of cover board often covers metal roof decks and low-sloped roofs, and you’ll find them more often in commercial roofings. However, they’ve become more popular for residential homes with torch-down roofing or single-ply roofing systems. 

Polyiso cover boards possess high thermal properties all while being lightweight and durable. The downside to high-density cover boards is that they tend to cost more than fiberglass or spray foam insulation at around $0.70 to $1 per foot. They’re also more likely to lead to condensation issues between the two layers compared to other cover board materials.

4. Gypsum Cover Boards

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For areas prone to fire hazards, gypsum cover boards, or drywall, combine a noncombustible, water-resistant core with a paper or fiberglass surface for affordable insulation for your roof. Gypsum cover boards cost around $0.40 to $0.65 per foot. You can use gypsum cover boards as a thermal barrier on the joints of your roof or install them over roof decks.

The disadvantages of gypsum cover boards are that they’re difficult to install in atypical locations, susceptible to damage on impact, and environmentally unfriendly. The U.S. Environmental Protection Agency (EPA) states that most drywall products end up in landfills, where they generate hydrogen sulfide gas—a chemical that can harm humans and wildlife. 

More concerning for the average homeowner is that gypsum can leach chemicals when it comes in contact with water. It also requires more energy to produce gypsum than other insulation options. However, you can circumvent negative environmental impacts by opting for reclaimed gypsum composites. 

5. Perlite Cover Boards

One of the oldest cover boards on the market is the perlite cover board. Coming in between $0.30 to $0.50 per foot, this fire-resistant and lightweight cover board contains a mix-match of materials, including perlite ore, cellulose fibers, asphalt, and binders. If you’re looking for an environmentally friendly fiberglass alternative for your home, you’ll love that perlite cover boards tend to come from recycled materials. 

A big con to choosing perlite cover boards is that they are not moisture-resistant and, therefore, aren’t a good option for humid climates. Perlite is also susceptible to blistering and ripping. 

6. Wood Fiber Cover Boards

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Wood fiber cover boards offer a natural high thermal barrier to your home, helping to keep your home warm in the winter and cool in the summer. These rigid panels come in various densities for homes in all regions. They’re common in cathedral ceilings and homes with open attic spaces. 

Keep in mind that wood fiber cover boards are prone to fire hazards and can be unsustainable if you don’t opt for wood fiber from a responsibly-harvested manufacturer. These cover boards sport a much higher price tag than most other insulation choices, costing $5 to $14 per foot, on average. They’re also newer to the market, making them a less available option for homeowners who live in rural locations.

7. Fiber Cement Cover Boards

One of the most durable roof insulation materials is fiber cement. This roofing material contains a mixture of cement, sand, and cellulose fibers for extra reinforcement, making it a popular option in residential homes. It’s readily available, weather-resistant, fire-resistant, mold-resistant, and pest-resistant, making it an optimal choice for homes with harsher weather, like ones near the coast or in tornado or fire zones. 

The downsides to fiber cement boards are that they cost significantly more than other options and weigh more, making them harder to install. Anticipate spending between $5 to $14 per foot to install fiber cement boards.

8. Structural Insulated Panels

Structural insulated panels (SIPs) are a type of prefabricated insulation material made from insulating foam or polystyrene sandwiched between two sheets of oriented strand board. This composite gives SIPs a strong structural advantage over some of the other types of insulation you can use for your roof’s insulation. 

These panels serve as a strong thermal insulator—better even than fiber insulation—and they have the price tag to prove it, coming in between $7 and $12 per square foot, on average. However, their airtight characteristics can actually be their downfall when it comes to installing this insulation for your home’s roof. SIPs are so good at minimizing airflow that they can prevent ventilation. 

If you decide to use this insulation type, then you may need to take steps to install mechanical ventilation to prevent condensation and mold problems. Similarly, SIPs are susceptible to moisture damage, which can be harder to detect in a roof with such structurally tight insulation material. 

Who to Contact if You Want Roof Insulation Installed?

If you've chosen your roof insulation type and want to hire a professional to complete your project, you may be wondering which professional is best for installing roof insulation: roofers or insulation contractors. While a roofer can inspect your roof before you install insulation, the best person for the job is a professional roof sealer near you. 

A roof sealer specializes in keeping roofs sealed, and is specialized in ensuring your insulation will insulate your home without negatively impacting your home’s airflow.