Add a buffer to your comfort zone
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 life span. Learn about eight popular roof insulation types for your home.
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.
The main difference between attic insulation and roof insulation is where the material is installed. Attic insulation is added to the attic floor—which is also the ceiling of the room below—whereas roof insulation is on the underside of the roof deck. They both use similar materials, but roof insulation prevents heat loss through the roof, while attic insulation helps regulate the living space below.
R-value is a measure of thermal resistance, showing how well insulation resists heat transfer. For roofs and walls, R-value technically means the same thing, but its required levels differ based on each area's exposure to the elements and heat loss and gain patterns. Roofs are more exposed to sunlight and weather extremes than walls, which means they need higher R-values to maintain indoor temperatures efficiently.
For instance, insulation requirements for a roof in a hot, sunny climate might need to counteract heat gain, while a roof in a cold climate needs to retain indoor warmth. Walls, being less exposed, require lower R-values than roofs. Ultimately, each part of a building needs insulation tailored to its specific environmental exposure to maximize energy efficiency and indoor comfort, which is why R-value guidelines vary between roof and wall insulation.
Fiberglass batts are one of the more popular types of roof 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.
| Fiberglass Batts Pros | Fiberglass Batts Cons |
|---|---|
| Most affordable | Bulky |
| DIY-friendly | Hazardous to inhale |
| Wide selection of R-values | Susceptible to water vapors |
Best for: Budget-conscious homes needing DIY options.
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.
| Spray Foam Insulation Pros | Spray Foam Insulation Cons |
|---|---|
| Easy installation | Expensive |
| Covers nooks and crannies | Requires professional installation |
Best for: Unconventional roofing designs or hard-to-reach areas.
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.
| High-Density Polyiso Cover Boards Pros | High-Density Polyiso Cover Boards Cons |
|---|---|
| High R-value | Higher price |
| Can be used on the exterior | More difficult to install |
Best for: Homes needing high thermal resistance.
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 roof insulation. Gypsum cover boards cost around $0.40 to $0.65 per foot. You can use them 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.
| Gypsum Cover Boards Pros | Gypsum Cover Boards Cons |
|---|---|
| Fire-resistant | Difficult to install |
| Affordable | Weak |
| Water-resistant | Environmentally unfriendly |
Best for: Fire-prone areas needing affordable insulation.
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.
| Perlite Cover Boards Pros | Perlite Cover Boards Cons |
|---|---|
| Fire-resistant | Susceptible to moisture |
| Lightweight | Rips and blisters easily |
| Eco-friendly | Won’t work in humid areas |
Best for: Eco-conscious homes in dry climates.
Loose-fill insulation consists of small particles of material, such as fiberglass, cellulose, or mineral wool, that can be easily blown into attics or wall cavities. It is ideal for filling irregular spaces and hard-to-reach areas, ensuring comprehensive coverage and minimal thermal bridging. Loose-fill insulation provides good soundproofing and is more cost-effective than other types of insulation.
However, loose-fill insulation can settle over time, reducing its effectiveness and R-value. It may also be less effective at preventing air leaks compared to more rigid materials. Additionally, proper installation requires specialized equipment, which requires a professional
| Loose-Fill Pros | Loose-Fill Cons |
|---|---|
| Fills irregular spaces | Settles over time |
| Good soundproofing | Requires professional installation |
| Cost-effective | Can have air leaks |
Best for: Roofs and homes with irregular cavities or attics needing coverage.
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 of fiber cement boards are that they cost significantly more than other options and weigh more, making them harder to install. Anticipate spending between $5 and $14 per foot to install fiber cement boards.
| Fiber Cement Cover Boards Pros | Fiber Cement Cover Boards Cons |
|---|---|
| Durable | Heavier |
| Weather-, mold-, and fire-resistant | More expensive |
Best for: Homes in extreme weather areas.
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, you may need to install mechanical ventilation to prevent condensation and mold. Similarly, SIPs are susceptible to moisture damage, which can be harder to detect in a roof with such structurally tight insulation material.
| Structural Insulated Panels Pros | Structural Insulated Panels Cons |
|---|---|
| Eco-friendly | Susceptible to moisture |
| Energy-efficient | Poor ventilation |
| Strong | Expensive |
Best for: Homes needing strong thermal insulation and structural support.
Your local climate, roof style, budget, and more will determine which roof insulation type is best for your home. Here’s what to consider.
Assess your climate. Homes in colder areas require higher R-values to retain heat, while those in warmer climates may need insulation that reflects heat.
Evaluate the roof. Pay close attention to your home's type of roofing and structural features—unconventional designs might benefit from spray foam for better coverage, while traditional attics can accommodate batts or loose fill.
Weigh the pros and cons of insulation materials. Consider the advantages and disadvantages carefully, including cost, ease of installation, and environmental impact. For instance, fiberglass batts are budget-friendly and DIY-friendly, while rigid foam offers high R-values but at a higher cost.
Consider moisture issues. Pay close attention to any potential moisture issues in your area, as some materials are more susceptible to damage.
Plan for costs. Take note of how much your chosen insulation material and labor will cost you. Installing insulation costs an average of $1,850.
Hire a professional. Do research to learn who installs insulation in your area to ensure you make an informed choice that aligns with your home’s specific needs and local building codes.
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 an insulation professional 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.
