How does the R-value of blown-in mineral wool compare to blown-in cellulose when used to top up attic insulation in a Dieppe home?

Blown-in mineral wool provides R-3.6 to R-4.0 per inch compared to cellulose at R-3.5 to R-3.8 per inch — a modest advantage that translates to needing about 10% less depth to achieve the same total R-value. For a Dieppe home targeting R-50 to R-60 attic insulation, you'd need roughly 12-14 inches of mineral wool versus 14-16 inches of cellulose.

The performance difference becomes more meaningful when you consider long-term stability and moisture resistance — critical factors in Dieppe's Maritime climate. Blown-in mineral wool (typically Rockwool or similar products) maintains its R-value permanently without settling, while cellulose settles 15-20% over the first few years. This means cellulose installed to R-50 may drop to R-40-42 after settling, requiring the installer to overfill initially to compensate.

Moisture management is where mineral wool truly excels in coastal New Brunswick. Dieppe's proximity to the Petitcodiac River and Bay of Fundy creates higher humidity conditions year-round. Mineral wool is hydrophobic — it repels moisture and maintains its insulating properties even when exposed to dampness from roof leaks or condensation. Cellulose, being made from recycled paper, can absorb moisture and lose R-value, though it does have good moisture-buffering properties that help regulate humidity swings.

Fire resistance strongly favors mineral wool — it's non-combustible up to 2,150°F, while cellulose relies on chemical fire retardants (borates) that can lose effectiveness over time. For Dieppe homeowners concerned about fire safety, especially in older homes with knob-and-tube wiring or recessed lighting, mineral wool provides superior protection.

Cost considerations tip toward cellulose — expect to pay $1.50-$3.00 per square foot for blown-in cellulose versus $2.00-$3.50 for blown-in mineral wool in the Dieppe area. For a typical 1,000 square foot attic top-up, that's roughly $500-$800 more for mineral wool. However, factor in the reduced settling and you may need 10-15% less material depth with mineral wool.

Installation characteristics differ significantly. Cellulose is lighter and easier to blow, making it faster to install and less stressful on older ceiling joists common in Dieppe's housing stock from the 1960s-1980s. Mineral wool is denser and requires more powerful blowing equipment, but achieves better coverage around obstacles and in tight spaces.

For sound control, mineral wool provides superior acoustic dampening — valuable if your Dieppe home is near Champlain Place, the airport flight path, or busy streets. The denser fiber structure absorbs sound transmission better than cellulose.

Both materials work well for attic top-ups in Dieppe's climate, but mineral wool is the premium choice if budget allows. Its moisture resistance, fire safety, dimensional stability, and slightly higher R-value per inch make it ideal for Maritime conditions. Cellulose remains an excellent, cost-effective option that provides good performance when properly installed with adequate overfill to account for settling.

Professional installation is recommended for both materials to ensure proper density, coverage around penetrations, and maintenance of soffit ventilation baffles. The performance difference between materials is often less important than proper installation technique and thorough air sealing of the attic floor before adding any insulation.

Need help finding a professional insulation contractor in the Dieppe area? New Brunswick Insulation can match you with local specialists experienced in both blown-in mineral wool and cellulose installations.