How does the cost per installed R-value compare between blown-in cellulose and blown-in fiberglass in a Fredericton NB wall cavity?

Blown-in cellulose typically provides better cost per R-value than blown-in fibreglass for wall cavity applications in Fredericton, delivering roughly 15-25% more insulating value per dollar invested.

When dense-packed into existing wall cavities (the most common retrofit method for Fredericton's housing stock of 1960s-1980s homes), cellulose achieves R-3.5 to R-3.8 per inch at the proper 3.5+ pounds per cubic foot density, while blown-in fibreglass typically delivers R-2.8 to R-3.2 per inch in wall applications. This means cellulose provides approximately 15-20% higher R-value per inch of thickness.

Material and installation costs in the Fredericton market run $2.50-$4.50 per square foot for dense-pack cellulose wall retrofit versus $2.25-$4.00 per square foot for blown-in fibreglass. While cellulose material costs slightly more, the higher R-value per inch means you need less thickness to achieve the same thermal performance. In a standard 2x4 wall cavity (3.5 inches deep), cellulose delivers R-12 to R-13.3, while fibreglass achieves R-9.8 to R-11.2 — meaning cellulose provides 15-25% better thermal performance for only 5-15% higher cost.

Beyond pure R-value economics, cellulose offers superior air sealing properties that fibreglass cannot match. When properly dense-packed, cellulose fills every gap, crack, and void in the wall cavity, significantly reducing air infiltration. This air sealing benefit often provides as much energy savings as the insulation itself — particularly important in Fredericton's windy river valley location where infiltration rates in older homes commonly test at 10-15 ACH50. Fibreglass, even when blown-in, does not achieve the same level of air sealing and cavity filling.

Cellulose also handles Fredericton's variable moisture conditions better than fibreglass. Made from recycled newspaper treated with borate fire retardant, cellulose can absorb and release moisture without losing R-value or developing mould — important during Fredericton's humid summers when moisture drive reverses and walls need to dry inward. Fibreglass loses thermal performance when wet and does not buffer moisture effectively.

The settling factor slightly favors fibreglass — cellulose settles 15-20% over the first few years while fibreglass settles only 2-5%. However, experienced contractors account for this by overfilling cellulose installations, and the superior initial R-value means cellulose still outperforms fibreglass even after settling.

For Fredericton homeowners, cellulose typically provides 20-30% better overall value when you factor in the higher R-value per inch, superior air sealing, moisture buffering, and fire resistance. The slightly higher upfront cost pays back through lower heating bills — particularly important given Fredericton's 4,800+ heating degree days and heating costs that can reach $3,000-$5,000 annually in poorly insulated homes.

Professional installation is essential for both materials to achieve these performance levels. Dense-pack cellulose requires specialized equipment and experience to achieve the proper density without over-packing (which can bow drywall) or under-packing (which reduces R-value and air sealing). The technique involves drilling access holes, inserting fill tubes, and monitoring cavity pressure — definitely not a DIY project.

For the best cost-effectiveness in Fredericton's climate, choose dense-pack cellulose for wall retrofits. The combination of higher R-value, superior air sealing, and moisture management typically provides 20-25% better return on investment compared to blown-in fibreglass, making it the preferred choice for most wall insulation projects in the Capital Region.

Need help finding a professional insulation contractor experienced with dense-pack cellulose installation? New Brunswick Insulation can match you with qualified contractors in the Fredericton area for free estimates.