Insulating Materials That Are Suitable For Your Roof

Roof insulation is important in improving thermal efficiency and regulating temperature across seasons. Whether dealing with scorching heat or freezing winters, choosing the right roof insulation materials can help reduce energy bills, minimize outside noise, and protect building structure from long-term damage.

But many forget: even the best types of roof insulation won't be effective if you can't safely access your roof for regular inspection and maintenance. That's why—besides using the right insulation material—it's smart to install a durable and insulated roof hatch to ensure safe, convenient access.

Most Common Roof Insulation Materials

1. Fiberglass Insulation or Glass Wool Insulation

Fiberglass insulation, often called glass wool insulation, is one of the most widely used roof insulation materials. It's made from fine strands of recycled glass and sand, spun into a soft, wool-like form. Its affordability and thermal performance make it a go-to option for residential and light commercial buildings.

Typically installed as batts, rolls, or loose-fill, fiberglass works well in attics and pitched roof cavities. According to the U.S. Department of Energy, its R-value ranges between R-3.1 and R-4.3 per inch. Fiberglass provides reliable thermal insulation while remaining cost-effective. Just install a vapor barrier when necessary to avoid moisture issues.

Not sure what R-value your roof and roof hatch need? Call 1-800-483-0823 for a quick consultation or explore our Construction Innovation Hub for insights on insulation and sustainable building solutions.

2. Polyisocyanurate (Polyiso) Foam Insulation

If you need high insulation performance per inch, polyisocyanurate—commonly known as polyiso—is an excellent choice. This rigid foam board is often used in commercial flat roofs due to its outstanding R-value and compatibility with single-ply membrane systems.

It insulates 30-40% better than EPS foam for equivalent thickness, though R-values can decrease over time due to thermal drift within the first two years after installation.

Polyiso boards are typically installed above the roof deck in a continuous insulation layer, helping to prevent thermal bridging. They're also lightweight, reducing structural loads without compromising performance.

3. Expanded Polystyrene (EPS) Foam Insulation

EPS foam offers a cost-effective and moisture-resistant solution for roofing insulation. While its R-value is lower than polyiso's, EPS provides good long-term thermal performance and resists water absorption better than fiberglass.

You'll often find EPS used in residential and commercial roofs where budget and moisture control are priorities. It's commonly available as rigid boards that can be cut to fit complex roof shapes.

4. Extruded Polystyrene (XPS) Foam Insulation

XPS foam is denser and more moisture-resistant than EPS, making it ideal for harsh environments. Its higher compressive strength allows it to support heavier roof loads without sagging or degrading over time.

XPS insulation is often used under roof membranes in flat commercial roof assemblies. Its closed-cell structure keeps water out, making it ideal for cold climates where freeze-thaw cycles are a concern.

5. Cellulose Insulation

Made from recycled newspaper and treated with fire-retardants, cellulose insulation is an eco-friendly option with great thermal performance. It's typically used in blown-in insulation and is perfect for retrofitting roof cavities that are hard to access.

Since it fills gaps and voids thoroughly, cellulose helps reduce air leaks and thermal bridging. However, it must remain dry, so proper roof waterproofing is important if you choose this option.

6. Rock Wool or Mineral Wool Insulation

Mineral wool insulation is produced from basalt or slag and spun into dense, fibrous batts or loose-fill material. It's naturally fire-resistant and doesn't absorb water, making it ideal for buildings requiring higher fire ratings or soundproofing.

In commercial roofs and industrial applications, mineral wool offers consistent thermal performance, even at high temperatures. It also maintains its shape and structure over time, which helps ensure lasting energy efficiency.

Need access solutions that match your fire-rated roof assembly? Explore our fire-rated roof hatches designed for durability and compliance, or get fully customizable models that meet your needs.

Five Types of Roof Insulation and Systems

Understanding the insulation materials is important, but knowing how they are applied can help optimize your installation and performance. Below are five common types of roof insulation designed for different needs:

1. Blanket Insulation (Batts and Rolls)

Blanket insulation consists of batts or rolls made from roof insulation materials like fiberglass or mineral wool. These are laid between rafters or joists in pitched roofs. It's an affordable, straightforward option for new constructions or accessible attic spaces.

2. Rigid Foam Board Insulation

Rigid boards made from polyiso, XPS, or EPS provide high thermal resistance and are widely used in commercial flat roofs. They're usually installed in layers over the roof deck, sometimes with staggered joints to eliminate gaps and reduce heat loss.

3. Blown-In Insulation

This method involves blowing loose insulation material—typically fiberglass, cellulose, or mineral wool—into roof cavities. It's ideal for retrofits or hard-to-reach spaces, as the material fills nooks and crannies for a seamless thermal barrier.

4. Spray Foam Insulation

Spray polyurethane foam expands to fill spaces and seals gaps while offering a high R-value per inch. It's excellent for insulating around penetrations, curbs, and irregular roof shapes. Additionally, spray foam adds structural rigidity and acts as an air barrier.

5. Reflective Insulation (Radiant Barriers)

Made from foil-faced materials, reflective insulation is designed to reflect radiant heat rather than to absorb it. It's especially useful in hot climates and is usually installed below the roof deck to minimize heat gain in attics.

Make the Right Choice for Your Roof

Choosing the type of roof insulation and the right roof insulation material depends on several factors, including the climate, roof structure, budget, and energy goals. Whether you prioritize thermal performance, moisture resistance, or eco-friendliness, there's an option that fits your project.

Our team is here to help you insulate smarter with recommendations and solutions, such as custom roof hatches designed to work seamlessly with your insulation material and type.

Contact us today for expert guidance or take it further by joining our Pro Club to get priority quotes, shipping, and a dedicated account executive.