8 Best Roof Insulation Types (2024)

By Amanda Lutz Updated February 5, 2024

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Investing in a new roof that’s properly insulated is wise for any homeowner who wants to lower energy bills and add a layer of protection to their home. Below, we’ll examine some of the most popular types of roof insulations, explain what an R-value is, and guide you through the insulation installation process.



Defining Roof Insulation R-Values

Certain insulation types allow heat to travel more freely than other types. Insulation types with higher R-values reduce heat flow and prevent heat loss, while insulation types with lower R-values don’t hold heat as effectively.

ENERGY STAR, a program run by the United States Environmental Protection Agency (EPA) and the United States Department of Energy, provides information on energy efficiency and rates roof insulation types using the R-value measurement system. Consider what ENERGY STAR recommends for your area when selecting your insulation.



1. Fiber Cement Cover Boards

Fiber cement boards are made of cellulose, sand, and cement, making them a durable option. This type of insulation is fire-resistant and stands up to extreme weather, so you can install it in harsh climates. The heaviness of fiber cement boards makes them difficult to install, and they’re more expensive than some other insulation options.

Cost: $5 to $14 per foot*

R-Value: Less than 1

Benefits and Drawbacks

Is structurally stable
➕ Prevents thermal bridging
➕ Stands up to extreme weather conditions

➖ Is expensive
➖ Is difficult to install

*Cost and R-value data in this article were gathered from Angi and NACHI.



2. Fiberglass Batt Insulation

Fiberglass batts are the most common insulation type. They’re inexpensive, moisture-resistant, and available in many shapes and sizes. You may need to use multiple layers when insulating a home in a colder climate. Manufacturers use a lot of energy to make fiberglass batts, so they aren’t as environmentally friendly as other insulation options.

If you’re installing this insulation type yourself, wear protective gear to avoid inhaling potentially hazardous glass fibers.

Cost: $0.30 to $1.50 per foot

R-Value: R-2.2 to R-4.5 per inch

Benefits and Drawbacks

➕ Comes in a variety of shapes and sizes
➕ Is budget-friendly
➕ Is easy to install

➖ Is toxic when mishandled
➖ Is hazardous for the environment



3. Gypsum Cover Boards

A gypsum cover board, or drywall, has a low R-value, so you’ll need to pair it with supplemental insulation materials if you live in a colder climate. It can act as a thermal barrier between other insulation types and your living space, but it’s susceptible to damage and difficult to install.

Cost: $0.40 to $0.65 per foot

R-Value: Less than 1

Benefits and Drawbacks

➕ Is inexpensive
➕ Acts as a thermal barrier
➕ Can be paired with supplemental insulation

➖ Has a low R-value
➖ Is susceptible to damage



4. Loose-Fill/Blown-In Insulation

Loose-fill, or blown-in, insulation is made up of small particles from different recycled materials, including cellulose, mineral wool, and fiberglass. Contractors use it in irregularly shaped areas because of its malleable consistency. However, it’s messy and prone to fungal growth if it gets wet. If you don’t install it properly, the ceiling may sag under its weight.

Cost: $0.50 to $2.50 per foot

R-Value: R-2.5 to R-3.7

Benefits and Drawbacks

➕ Is easy to install and malleable
➕ Boasts eco-friendly materials
➕ Is flame-resistant

➖ Is messy to install
➖ Grows mold when wet



5. Perlite Cover Boards

Perlite ore, fiber, asphalt, and starch binders create perlite cover boards, which are environmentally friendly. These cover boards are lightweight and fire-resistant, so they’re easy to install. However, you can’t install them in a room with high moisture content because they could blister.

Cost: $0.30 to $0.50 per foot

R-Value: R-2.7 per inch

Benefits and Drawbacks

➕ Is eco-friendly
➕ Is easy to install
➕ Features fire-resistance

➖ Isn’t suitable in humid locations
➖ Features a lower R-value



6. Rigid Insulation Boards (High-Density Polyiso Cover Boards)

Expanded polystyrene (EPS), extruded polystyrene (XPS), and polyisocyanurate (polyiso) are the three rigid cover board types. They all have high R-values and prevent thermal bridging, which occurs when heat moves toward more conductive materials. However, rigid insulation boards are expensive, aren’t durable, and likely require professional installation.

Cost: $0.70 to $1 per foot

R-Value: R-6.5 to R-6.8 per inch

Benefits and Drawbacks

➕ Features a higher R-value
➕ Is moisture-resistant
➕ Prevents thermal bridging

➖ Isn’t durable
➖ Requires professional installation



7. Spray Foam Insulation

Spray foam insulation is easy to install and is partially composed of polyurethane, a plastic that effectively seals cracks. It has a high R-value, is moisture-resistant, and can fill small spaces. The cost of spray foam insulation is on the higher end of insulation pricing, but it lasts longer than other types, such as fiberglass.

Cost: $0.50 to $2 per foot

R-Value: R-3.8 to R-7 per inch

Benefits and Drawbacks

➕ Features a high R-value
➕ Is easy to install
➕ Is moisture-resistant

➖ Is more expensive than other insulation types
➖ Requires professional installation



8. Structural Insulated Panels

Structural insulated panels (SIPS) are flat panels made of insulation that’s sandwiched between plywood. SIPS offer extra support to your structure and will prevent most air leaks. They’re more difficult to install, less sustainable, and more expensive than other roof insulation models.

Cost: $4 to $7 per square foot

R-Value: Varies, up to R-4.5 per inch

Benefits and Drawbacks

➕ Is structurally stable
➕ Prevents thermal bridging
➕ Features a higher R-value than other insulation types

➖ Is expensive
➖ Is difficult to install



Choosing Roof Insulation for Your Home

The best insulation type depends on your particular home and needs. If you need a new roof, SIPS or fiberglass batts may be your best bet for insulation. If you need to fix your roof and reinsulate your home, use something easy to install, such as a spray foam.

Consider the following when making your choice:



Our Recommendation

We recommend using rigid foam insulation in most cases because it has a high R-value and will boost your energy savings. It’s recyclable when you need to replace it, and it’s more affordable than some other high-R-value insulations.



Best Roof Insulation FAQ

What roof insulation has the highest R-value?

The roof insulation with the highest R-value is the rigid insulation board. It comes in three different types, all of which prevent thermal bridging. Although it’s more expensive than other insulation types, it offers the highest energy savings because of its R-value.

What are the benefits of roof insulation?

Roof insulation can save you up to 20% in heating and cooling costs. Most roofers recommend insulation. Insulation also acts as another layer of protection in your home.

What is the best roof insulation for a metal roof?

The best roof insulation for a metal roof is rigid board insulation. It’s ideal for new roof installations because it has the highest R-value and is good at soundproofing. If you’re looking for insulation during a home improvement repair or update, you can choose spray foam because of its high R-value and easy installation process.