What R-value insulation do I need for walls and attic in New Brunswick?

New Brunswick's current building code targets R-22 minimum for walls (in new construction) and R-50 to R-60 for attics — but in existing NB homes, the attic upgrade almost always delivers the best return on investment and should be prioritized before walls if your budget requires a choice.

R-value is the measure of thermal resistance — the higher the R-value, the better the insulation resists heat flow. NB falls into a heating climate zone where the required R-values are higher than warmer Canadian provinces, reflecting the province's long, cold heating season. Understanding both the code minimums and the practical performance targets for existing NB homes gives you a clear framework for any insulation upgrade.

For attics, the National Building Code as adopted in NB calls for minimum R-50 in the ceiling/attic floor assembly. Many energy advisors and NB Power's efficiency programs recommend pushing to R-60 to R-80 for maximum payback, particularly in northern NB communities like Edmundston and Campbellton where heating degree days are significantly higher than coastal Moncton or Saint John. The good news is that attic insulation is cheap and effective — blown-in cellulose or fibre glass at R-50 to R-60 costs approximately $1.50-$3.00 per sq ft installed, making a 1,000 sq ft attic upgrade a $1,500-$3,000 investment with an exceptional payback period. Most older NB homes have R-12 to R-20 in the attic — less than half of what is needed — making this the single highest-impact upgrade available.

For walls in new construction or full gut renovations, NB building code targets an effective whole-wall R-value in the R-22 range, typically achieved through R-20 batt insulation in a 2x6 framed wall plus continuous exterior insulation to address thermal bridging through the studs. In existing homes with 2x4 framing, filling the cavity with R-15 dense-pack insulation and adding R-7.5 to R-10 of exterior continuous foam gives a whole-wall performance of approximately R-20 to R-22 effective — close to code-equivalent performance in a renovation context.

Basement walls should target R-20 minimum in NB. As discussed earlier, closed-cell spray foam or rigid foam board are the appropriate materials — fibre glass batts against concrete are not. Three inches of closed-cell spray foam at R-6.5 per inch delivers approximately R-20, while 4 inches of rigid XPS board (R-5 per inch) delivers R-20 plus the air barrier function when joints are taped.

For cathedral ceilings and sloped roof assemblies — common in renovated older NB homes and additions — achieving adequate R-value is challenging because rafter depths limit insulation thickness. A 2x10 rafter provides 9.25 inches of depth. Filling with R-30 spray foam and adding exterior continuous foam board over the roof deck (under new sheathing and roofing) can push total assembly values to R-40+. This is a more complex and costly assembly but necessary for high-performance renovation work in NB's climate.

The practical priority order for most NB homeowners working through existing homes is: attic first (biggest heat loss, easiest and cheapest to address), rim joists second (disproportionate air leakage relative to their area), basement walls third (moisture management and comfort), and above-grade walls last (expensive and disruptive to improve significantly in a finished home). An energy audit helps confirm whether this sequence makes sense for your specific home or whether unusual conditions — a home with an already-insulated attic but bare concrete basement walls, for example — suggest a different priority. For whole-home insulation work as part of a major renovation, New Brunswick Renovations can connect you with experienced local contractors through the New Brunswick Construction Network directory.

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Looking for experienced contractors? The New Brunswick Construction Network connects homeowners with qualified professionals:

• Gionetterenovations
• Thirty Four Renovations