Cellulose vs. Fiberglass: Which Blown-In Insulation is Best for Calgary?

If you are planning to upgrade your attic, lower your monthly energy bills, and protect your home from Alberta’s harsh climate, you have likely narrowed your search down to two primary materials: cellulose and fiberglass.

Both of these options are installed using heavy pneumatic equipment to blow loose-fill material evenly across your attic space. However, they are made from entirely different materials, offer different thermal benefits, and react differently to Calgary’s extreme climate fluctuations.

Let’s break down the pros, cons, and direct differences between blown-in cellulose and blown-in fiberglass so you can make the absolute best choice for your home.

What is Blown-In Cellulose Insulation?

Cellulose is an eco-friendly insulation material made up of approximately 85% recycled newspaper and cardboard. The paper fibers are treated with natural borate minerals to make the material highly fire-retardant, mold-resistant, and insect-repellent.

The Pros of Cellulose in Calgary:

• Higher R-Value Per Inch: Cellulose has a higher density than fiberglass, offering an insulating value of roughly R-3.5 to R-3.8 per inch. This means you need slightly less material depth to reach modern targets like R-60.
  

• Superior Air Sealing: Because cellulose is a dense, organic wood fiber, it is incredibly effective at blocking micro-drafts and slowing down natural air movement within your attic cavity.
  

• Natural Pest Resistance: The borates used to treat cellulose are harmless to humans and pets but are highly hostile to ants, mice, and other pests that occasionally find their way into residential rooflines.
  

• Exceptional Sound Dampening: If you are tired of hearing the loud whistle of Chinook winds or overhead street traffic, dense-pack cellulose acts as a fantastic acoustic barrier.
  

The Cons of Cellulose:

• Heavier Material Weight: Cellulose is heavier than fiberglass. If your ceiling drywall is thin or your ceiling joists are spaced too far apart, the sheer weight of a thick R-60 top-up must be planned carefully to prevent drywall bowing.
  

• Initial Installation Dust: During the blow-in process, cellulose generates more temporary paper dust than fiberglass, though this settles completely within 24 hours of installation.
  

What is Blown-In Fiberglass Insulation?

Fiberglass loose-fill insulation is created by melting down sand and glass (often utilizing up to 50% recycled glass content) and spinning it into lightweight, fluffy glass fibers.

The Pros of Fiberglass in Calgary:

• Extremely Lightweight: Fiberglass is incredibly light. This makes it the ideal choice for older homes with aged framing or thinner drywall, as it places virtually zero structural weight on your ceiling.
  

• Completely Fireproof: Because fiberglass is spun from glass, it is naturally non-combustible and does not require chemical treatments to achieve a Class A fire rating.
  

• Less Installation Dust: Blown-in fiberglass generates very little dust during the application process, allowing for a slightly cleaner and faster installation.
  

• Will Not Absorb Water: While you never want water in your attic, if a roof leak occurs, fiberglass fibers will not absorb moisture or settle as heavily as wet paper fibers.
  

The Cons of Fiberglass:

• Lower R-Value Per Inch: Fiberglass has an insulating value of roughly R-2.5 to R-3.0 per inch. To reach a high-performing R-60 standard, you will need a thicker layer (usually around 18 to 22 inches) compared to cellulose.
  

• Air Flow Susceptibility: Because fiberglass is fluffy and less dense, high-volume air currents can move through it more easily, making comprehensive pre-insulation air sealing absolutely critical.
  

The Calgary Weather Verdict: Which One Wins?

In Calgary, where winter temperatures routinely plunge below -30°C and summer temperatures soar above 30°C, both materials can perform beautifully if installed correctly. However, our local climate science highlights a few key considerations:

The "Convective Loop" Factor

When it gets extremely cold outside, the temperature difference between your warm ceiling and your freezing cold attic deck can create "convection currents" inside fluffy insulation. Because fiberglass is less dense, it can lose a small percentage of its thermal resistance during deep freezes unless it is blown to a higher density. Cellulose is naturally denser, meaning it resists these convective loops better when the temperature drops during cold snaps.

The Ventilation Factor

Regardless of which material you choose, your attic must have balanced airflow to prevent condensation. If your intake airflow from the soffit vents is blocked, moisture will pool on your insulation. No matter if you select cellulose or fiberglass, we always install durable rafter baffles and inspect your soffit and fascia ventilation before blowing any material.

Summary: How to Choose for Your Attic

• Choose Blown-In Cellulose if: You want the highest possible energy efficiency per inch, want to block drafts without major drywall work, want excellent sound dampening, and prefer eco-friendly, recycled materials.
  

• Choose Blown-In Fiberglass if: You have an older home with delicate ceiling framing, want to minimize weight on your drywall, or want a clean, fast installation with material that is naturally moisture-resistant.
  

Get an Expert Attic Recommendation Today

The best insulation material for your home depends on your roof’s pitch, the condition of your existing vapor barrier, and the strength of your ceiling framing.

At Integral Construction, we don't believe in a one-size-fits-all approach. We perform a complete, hands-on attic inspection to evaluate your ventilation, identify draft paths, and help you select the ideal material for your budget and energy goals.

Ready to lower your heating bills? Contact Nate at Integral Construction today to schedule your free, no-obligation attic assessment or check out our complete line of home renovation services. Call Nate Today: 403-978-5553

Email: Natebirse@me.com

Serving: Calgary, Airdrie, Okotoks, Cochrane, and Surrounding Areas

Our Services: Blown-in Insulation, Windows, Doors, Siding, Roofing, Decks & Fences, Soffits & Fascia, Gutters, Carpentry.