What R-value insulation do I need in my walls to meet code in New Brunswick?

For walls in New Brunswick, you need a minimum R-20 effective thermal resistance to meet the National Building Code of Canada 2020 edition, which New Brunswick has adopted with Tier 2 energy efficiency mandatory as of May 1, 2025 for new applications.

This R-20 requirement applies to above-grade walls in heated spaces. The "effective" part is important — it accounts for thermal bridging through studs and other structural elements, not just the insulation cavity value. With standard 2x6 construction (5.5" cavity), you'd typically use R-22 batt insulation to achieve the effective R-20 after accounting for thermal bridging through the wood framing.

Common wall assemblies that meet NB code include:

2x6 walls with R-22 batt insulation plus continuous exterior insulation (rigid foam or mineral wool) are becoming the standard approach. The continuous insulation layer reduces thermal bridging and helps achieve the effective R-20. Many builders are using 2" of rigid foam (R-10 to R-12) over the sheathing, combined with R-14 to R-16 cavity insulation.

Advanced framing techniques like 2x8 walls allow for R-28+ cavity insulation, easily exceeding code minimums. Double-wall construction (staggered stud or Larsen truss systems) can achieve R-30 to R-40+ but adds complexity and cost.

For existing home renovations, you'll need to work within your current wall thickness. If you have 2x4 walls (3.5" cavity), R-14 batt is the maximum you can fit, which won't meet current code for new construction. However, existing homes aren't required to upgrade to current code unless you're doing major renovations that trigger permit requirements.

The building permit authority in your area — whether your municipality or Regional Service Commission for rural areas — will review your insulation plans during the permit process. They'll want to see how you're achieving the effective R-20, including details on vapor barriers, air sealing, and thermal bridge management.

NB Power offers rebates through their Total Home Energy Savings Program for insulation upgrades that exceed minimum code requirements, which can help offset the cost of going beyond the R-20 minimum. Given New Brunswick's harsh winters with temperatures regularly hitting -25°C to -35°C, many homeowners choose to exceed code minimums for better comfort and energy savings.

For your specific project, contact your local building inspector to confirm the exact requirements and get approval for your chosen wall assembly before starting work.