Blown-In vs. Fiberglass Insulation: Which Is Best for Ottawa Homes?

The Great Insulation Debate: Making the Right Choice for Ottawa’s Extreme Climate

Ottawa homeowners know the struggle: brutal winters with deep freezes and windy polar vortexes, followed by hot, humid summers. Your home’s insulation is the first line of defense against these extremes. When upgrading, the most common question is: fiberglass batts or blown-in insulation?

While both materials have been used for decades, they perform very differently in real-world conditions—especially in older Ottawa homes with irregular attics, settled structures, and complex framing. In this comprehensive comparison, we’ll examine coverage, performance, cost, longevity, and more to help you decide which is truly best for your home.

At Bison Insulation, we specialize in high-performance solutions tailored to Ottawa’s climate. Our blown-in insulation services in Ottawa consistently outperform traditional batts in retrofits, but let’s break down the facts.

Coverage and Installation: Where Blown-In Wins Decisively

The Gapping Problem with Fiberglass Batts

Fiberglass batts come in pre-cut rolls or rectangles designed for standard joist spacing. In new construction with perfect framing, they work reasonably well. However, most Ottawa homes—especially those built before 2000—have irregular joists, plumbing stacks, electrical boxes, recessed lights, and chimney chases.

Cutting batts to fit these obstacles almost always leaves small gaps and compressed areas. Even a 1-inch gap can reduce the effective R-value of an entire section by 50% or more. These “thermal bridges” allow heat to escape and cold air to infiltrate, creating cold spots and higher energy bills.

Seamless, Gap-Free Coverage with Blown-In Insulation

Blown-in insulation (loose-fill cellulose or fiberglass) is pneumatically installed, flowing into every nook, cranny, and irregular space like a dense blanket. It surrounds obstacles completely, eliminating gaps and thermal bridges.

This monolithic thermal barrier is especially valuable in Ottawa attics, where uneven settling and renovations over decades create complex geometries. The result: consistent temperatures throughout your home and maximum energy efficiency.

For attic upgrades, explore our full range of attic insulation services in Ottawa.

R-Value and Thermal Performance Comparison

Understanding R-Value in Real-World Conditions

R-value measures resistance to conductive heat flow. On paper, fiberglass batts and blown-in materials often have similar R-values per inch (around R-3.2 to R-4.0 for cellulose and R-2.9 to R-3.8 for fiberglass).

However, lab ratings don’t account for settling, compression, or air movement.

Long-Term R-Value Retention

• Fiberglass Batts: Over time, batts can sag or compress, especially if disturbed during attic access. Poor installation leads to voids that drastically reduce performance.
• Blown-In Cellulose: Settles predictably (about 10-15%) during installation, but professionals account for this to achieve the target settled R-value. Once settled, it remains stable for decades.
• Blown-In Fiberglass: Modern formulations settle minimally (less than 1%), maintaining R-value long-term.

In Ottawa’s Zone 6-7 climate, experts recommend R-60 for attics. Blown-in easily achieves this by adding depth over existing material, while batts often require full removal and replacement to reach the same level.

Air Sealing and Convection Control

Why Air Movement Matters More Than You Think

Up to 40% of heat loss in Canadian homes comes from air leakage and convection within insulation, not just conduction. Fiberglass batts are highly permeable to air—warm air can move freely through and around them.

Superior Air Infiltration Resistance with Blown-In

Dense-pack blown-in cellulose (installed at 3.5-4 lbs per cubic foot) significantly reduces air movement. It acts as both insulation and an air barrier, dramatically cutting convective heat loss.

This is critical during Ottawa’s polar vortex events, when wind-driven air infiltration can make homes feel drafty despite “adequate” insulation.

Blown-in fiberglass, when installed densely, also outperforms batts in air sealing, though cellulose generally edges it out in this category.

Soundproofing: A Bonus Benefit of Blown-In

Ottawa’s urban neighborhoods—near the 417, Queensway, or downtown—often deal with traffic noise. Dense blown-in cellulose excels at sound absorption, reducing noise transmission by up to 60% more than fiberglass batts.

This makes upper floors quieter and more comfortable, especially in older homes with minimal sound barriers between levels.

Moisture Management and Ice Dam Prevention

Ottawa’s Ice Dam Nightmare

Uneven heat loss through gaps in batt insulation causes snow to melt unevenly on roofs, leading to ice dams that damage shingles, gutters, and interiors.

How Blown-In Prevents Ice Dams

Uniform coverage keeps the entire attic cold, preventing warm spots that trigger melting. Combined with proper ventilation, blown-in insulation virtually eliminates ice dam formation.

Cellulose also has superior moisture-handling properties—it can absorb and release moisture without losing R-value or promoting mold, unlike fiberglass, which can sag when wet.

If your current insulation is damaged by past leaks or ice dams, professional insulation removal in Ottawa is essential before upgrading. For mold concerns, our mold removal services in Ottawa ensure a healthy foundation.

Environmental Impact and Sustainability

Eco-conscious Ottawa residents increasingly prioritize green building materials.

• Blown-In Cellulose: Made from 85%+ recycled paper (often newsprint), treated with non-toxic borates for fire and pest resistance. Low embodied carbon and excellent sustainability profile.
• Blown-In Fiberglass: Contains 40-60% recycled glass but requires more energy to manufacture.
• Fiberglass Batts: Similar recycled content but generates more waste during cutting and installation.

For homeowners seeking the greenest option, cellulose blown-in is the clear winner.

Cost Comparison: Initial vs Long-Term

Upfront Costs

Fiberglass batts are typically cheaper per square foot for materials, but labor-intensive installation in retrofits drives up total cost. Blown-in requires specialized equipment but installs faster—often in a single day.

In Ottawa, professional blown-in attic insulation usually costs slightly more upfront than batt replacement.

Long-Term Savings and ROI

Blown-in’s superior performance translates to 20-40% greater energy savings. With Ottawa’s high heating demands and rising energy costs, the payback period for blown-in is typically 4-7 years—often shorter with available rebates.

Batts may save money initially but cost more over time through higher bills and potential ice dam repairs.

Installation Considerations and Professional Expertise

DIY fiberglass batts are common, but mistakes are easy and costly. Blown-in requires professional equipment for proper density and coverage—DIY rental machines often produce inferior results.

Bison Insulation’s certified technicians ensure:

• Accurate depth calculations for target R-value
• Proper ventilation (soffit baffles, ridge vents)
• Air sealing of penetrations
• Minimal disruption and thorough cleanup

Versatility Across Your Home

While this comparison focuses on attics, blown-in shines in other applications:

• Dense-pack walls in retrofits (without tearing out drywall)
• Floor and crawl space insulation—see our floor insulation in Ottawa
• Hard-to-reach areas where batts simply can’t fit

For ultimate performance in rim joists or cathedral ceilings, many homeowners combine blown-in with targeted spray foam insulation in Ottawa.

When Fiberglass Batts Might Still Make Sense

To be fair, batts have their place:

• New construction with open, accessible framing
• Simple wall cavities in renovations
• Budget-conscious projects where maximum performance isn’t priority

However, for most Ottawa retrofit scenarios—especially attics—blown-in is the superior choice.

Conclusion: Blown-In is the Clear Champion for Ottawa Homes

After comparing coverage, performance, air sealing, moisture control, soundproofing, environmental impact, and long-term value, blown-in insulation emerges as the best option for the vast majority of Ottawa homeowners.

It delivers seamless protection against our extreme climate, lower energy bills, greater comfort, and fewer headaches like ice dams and cold spots.

Ready to upgrade your home’s performance? Contact Bison Insulation for a free assessment. Visit our homepage to explore all our insulation solutions and book your consultation today.

Make the smart choice—choose blown-in insulation for lasting comfort and savings.