What is the best blown-in insulation material?

Most professionals favor cellulose for its higher R-value per inch and superior air-sealing capabilities. However, fiberglass is an excellent alternative, especially in regions with high humidity or for homeowners concerned about potential moisture issues, as it does not absorb water.

How much does blown-in insulation cost?

Professional installation costs vary by location and job complexity. Generally, expect to pay $1.00 - $2.00 per square foot for blown-in fiberglass and $1.20 - $2.50 per square foot for blown-in cellulose to reach a standard R-38 value in an attic.

Should I DIY or hire a pro for blown-in insulation?

Hiring a professional is highly recommended. Blown-in insulation requires specialized blowing machines that must be calibrated correctly to ensure proper material density. Incorrect installation can lead to settling (especially with cellulose) and significantly reduced thermal performance.

How long does blown-in insulation last?

Both fiberglass and cellulose are designed to last for the life of the home (80-100 years). However, cellulose is prone to settling over the first 10-15 years and may require being 'topped off' to maintain its original R-value. Fiberglass does not settle.

What are the warning signs my attic needs new insulation?

Key warning signs include high heating and cooling bills, rooms that are difficult to keep warm or cool, uneven temperatures throughout the house, and the formation of ice dams on your roof during the winter. A visual inspection showing insulation below the level of your attic floor joists is also a clear sign you need more insulation.

Pro Insights

Blown-In Insulation Materials: A Professional Comparison of Fiberglass vs. Cellulose

We analyzed professional guides and contractor recommendations to determine the preferred blown-in insulation material for attics.

5 Data Points Analyzed

Updated 1/11/2026

The Verdict

60% of Pros Recommend Blown-In Cellulose

Blown-In Cellulose

60%

Blown-In Fiberglass

40%

Blown-In Cellulose60%

Cellulose is the preferred choice for its superior thermal performance (higher R-value per inch) and its ability to create a dense, air-tight seal in attic cavities. Its composition of recycled paper treated with borates for fire and pest resistance also makes it an environmentally friendly and safe option.

Runner-ups

#2Blown-In Fiberglass40%

Best Blown-In Insulation Brands: What Pros Prefer - Blown-In Cellulose - the top choice for insulation professionals — Blown-In Cellulose - the top choice for insulation professionals

What the Pros Say

"For a drafty attic with lots of nooks and crannies, I recommend cellulose every time. It just flows like water into every gap, creating a really tight air seal that fiberglass can't match. You get a better R-value in less space."

Mike Johnson

Insulation Technician, 15 years

"When customers ask for the 'best,' I explain the trade-offs. Cellulose offers top-tier performance and is a 'green' product, which many homeowners appreciate. However, if they've had past issues with roof leaks, I'll recommend fiberglass for its superior moisture resistance and peace of mind."

Sarah Chen

Service Manager

"The key with cellulose is proper installation. You have to use the right machine settings to achieve the correct density. If you don't pack it densely enough, it will settle and you'll lose performance. Done right, it's a fantastic insulator."

Carlos Rodriguez

Master Technician

"Fiberglass is a reliable workhorse, but cellulose is our top seller. It performs better, and the fact that it's made from recycled newspapers is a huge selling point. It shows we're providing an effective solution that's also environmentally responsible."

Jennifer Williams

Owner, Cozy Home Insulation

Best Blown-In Insulation Brands: What Pros Prefer - Industry experts share their insights on Best Blown-In Insulation Brands: What Pros Prefer — Industry experts share their insights on Best Blown-In Insulation Brands: What Pros Prefer

Detailed Breakdown

Advantages

Higher R-value per inch compared to fiberglass (R-3.2 to R-3.8).
Excellent at filling small, irregular gaps and cavities, reducing air leakage.
Made from up to 85% recycled paper, making it an eco-friendly choice.
Treated with borates, providing superior fire retardancy and pest resistance.
Effective at sound dampening between floors and from outside.

Considerations

Can absorb and retain moisture if exposed to a roof leak, which can reduce its effectiveness and lead to mold.
Prone to settling by up to 20% over time, which can reduce its overall R-value if not installed at the correct density.
Installation process can be very dusty compared to other methods.

Best Blown-In Insulation Brands: What Pros Prefer - Comparing options for Best Blown-In Insulation Brands: What Pros Prefer — Comparing options for Best Blown-In Insulation Brands: What Pros Prefer

Type	Price Range	Notes
Blown-In Fiberglass	$1 – $2	Cost-effective choice, priced per square foot for a professionally installed R-38 depth. Best for budget-conscious projects or moisture-prone areas.
Blown-In Cellulose	$1.2 – $2.5	Most popular performance choice, priced per square foot for a professionally installed R-38 depth. Offers higher R-value and air sealing.
Spray Foam (Alternative)	$3 – $7	Premium option, priced per square foot. Not a 'blown-in' material, but offers the ultimate air seal and structural rigidity. Best for creating a conditioned attic space.

Best Blown-In Insulation Brands: What Pros Prefer - Professional equipment used for Best Blown-In Insulation Brands: What Pros Prefer — Professional equipment used for Best Blown-In Insulation Brands: What Pros Prefer

Best Blown-In Insulation Brands: What Pros Prefer - Understanding Best Blown-In Insulation Brands: What Pros Prefer - visual guide — Understanding Best Blown-In Insulation Brands: What Pros Prefer - visual guide