What Insulation Is Best for Your Attic?

Type of Insulation for Attic – Comparing Insulation Types

Fiberglass insulation. Imagine heading to your local home improvement store, grabbing a few batts, and rolling them out across your attic floor in a single afternoon. This is fiberglass batt insulation that’s simple, affordable, and friendly for DIY projects. Just remember, it can irritate your skin and lungs without protective gear.

One advantage often overlooked is serviceability. Batts can be moved aside if you ever need to run new wiring, install ducts, or service your HVAC system, something that’s much harder with blown-in or spray foam insulation. They are also less likely to attract rodents compared to cellulose, giving them an edge in homes where pests are a concern. Fiberglass batts remain the most affordable insulating solution, especially for budget-conscious homeowners.

Blown-in insulation. Blown-in insulation is made from tiny glass fibers that are spun into a fluffy, wool-like material. During installation, it’s blown into the attic using a special machine, allowing it to fill gaps and cover irregular spaces that batts can’t reach. Perfect for older homes, blown-in fiberglass can snake into tight crevices. Think of it like spraying snow into every gap. Quick to apply and great for retrofits, but just like snow, it can “settle” over time, reducing its R-value.

Cellulose insulation. Cellulose insulation is produced from recycled paper products, mainly newsprint, treated with fire retardants to make it safe for residential use. It’s a loose-fill material that’s blown into the attic, where it creates a dense layer that resembles a blanket. This makes it especially attractive to eco-conscious homeowners. In dry climates, cellulose provides excellent coverage and soundproofing. But in humid areas, it can absorb moisture, clump, and compress, leaving bare spots that leak energy.

Spray foam (open/closed cell). Spray foam insulation is a mix of liquid chemicals on-site that rapidly expands into a hardened foam. There are two main types:

• Open-cell spray foam: Softer and lighter, with an R-value around 3.5 per inch. It expands more, making it effective for filling irregular cavities.
• Closed-cell spray foam: Denser and more rigid, with an R-value up to 6–7 per inch. It forms a highly effective air and moisture barrier that strengthens structural integrity.

Spray foam is the luxury option; it costs more upfront and requires professional installation, but it can save thousands over the system’s lifespan thanks to its superior efficiency. Closed-cell spray foam is also one of the most durable insulating materials, lasting for decades without performance loss.

Best Insulation for the Attic – Performance, Value & Top Choices

Every attic and, therefore, every homeowner has different priorities. The “best” insulation is not a one-size-fits-all choice but rather the material that balances performance, cost, and long-term value for your situation:

• If budget is the driver: Fiberglass batts remain the most affordable and accessible solution. They’re widely available, DIY-friendly, and provide decent R-values when layered correctly. Expect to pay around $0.20 to $1.00 per square foot installed, making them the best quick upgrade for budget-conscious homeowners.
• If eco-friendliness matters: Cellulose insulation is made from recycled paper, keeping waste out of landfills while providing excellent soundproofing. Installed cost usually falls between $1.00 and $1.50 per square foot, though its tendency to absorb moisture and settle makes it better suited for dry climates or well-ventilated attics.
• If comfort is a priority: Spray foam insulation is the gold standard. Closed-cell foam achieves R-6–7 per inch, delivering airtight, moisture-resistant performance. The tradeoff is cost, as it typically costs between $3.00 and $4.50 per square foot, but energy savings often pay back the investment within 5–7 years.
• If space is limited: Polyiso rigid foam insulation boards are ideal for shallow attic rafters or space-constrained attics. With R-5.5–6.5 per inch, they provide high performance in less thickness. Installed cost runs around $2.50 to $3.50 per square foot, making them pricier than batts but highly effective where every inch counts.

If you’re staying long-term and want maximum comfort, spray foam is worth the investment. For budget-friendly upgrades, fiberglass or blown-in is often the smarter choice. Green-minded homeowners may lean toward cellulose, while polyiso rigid foam shines when space is tight.

Best Blown Insulation for Attic – Top Picks & Expert Recommendations

Blown-in insulation is a smart way to insulate your attic because it can cover large areas quickly and fill in small gaps that batts often miss. Homeowners usually choose between fiberglass and cellulose, and the right option depends on your attic’s needs, climate, and budget.

Fiberglass is light, clean, and does not absorb much moisture. This makes it a safer choice for homes in humid areas. It is also less attractive to pests compared to cellulose. The main drawback is that fiberglass can settle over time, which lowers its R-value. This means you may need to “top it up” after a few years to keep the same level of insulation. Best for – damp climates, attics that need easier maintenance, and homeowners who want clean and long-lasting insulation.

Cellulose is made from recycled paper, which makes it eco-friendly and great for people who want a greener home. It is denser than fiberglass, so it gives better coverage and can block more air leaks and sound. However, cellulose can absorb moisture and also settle, which reduces its performance if the attic has poor ventilation. Best for – dry climates, well-ventilated attics, and homeowners who want strong coverage and an environmentally friendly solution.

Expert Guidance – Which One Should You Choose?

• Pick fiberglass if your attic may face dampness, or if you want insulation that is easier to service later.
• Pick cellulose if your attic stays dry and you want maximum coverage with an eco-friendly material.
• In many homes, either option will save money on energy bills. The key is to match the material to your attic’s condition.

Pro Tip from Beni, Senior Technician at Pure Eco Inc:

“Before you decide on fiberglass or cellulose, always check your attic ventilation. Good airflow stops moisture problems and makes both materials last longer. I’ve seen many homes where the insulation itself was fine, but poor ventilation ruined the performance within a few years.”