What are the NB building code minimum R-value requirements for walls in a new mini home installation?

New mini homes in New Brunswick must meet R-22 to R-28 effective thermal resistance for above-grade exterior walls under the current NB Building Code. This applies to all new residential construction including mini homes, manufactured homes, and modular homes installed on permanent foundations.

The "effective" R-value requirement is crucial because it accounts for thermal bridging through the wall framing. A standard 2x6 wall with R-22 batts between the studs only achieves about R-16 effective performance because the wood studs (roughly R-6) create thermal bridges that bypass the insulation. To meet true R-22 effective performance, the wall assembly needs either:

• 2x6 construction with R-22 batts plus R-5 continuous exterior insulation (rigid foam or mineral wool over the sheathing)
• 2x8 construction with R-28 batts (less common due to material costs)
• Advanced framing techniques with 2x6 studs at 24-inch centers plus continuous insulation

Most quality mini home manufacturers now build walls with 2x6 framing, R-22 batt insulation, and 1-2 inches of continuous exterior insulation (XPS or polyiso rigid foam) under the siding. This assembly meets code requirements and performs well in New Brunswick's Zone 6 climate with its 4,800-5,200 heating degree days annually.

Mini home-specific considerations include ensuring the vapour barrier (6-mil polyethylene) is properly installed on the interior side of the wall assembly and that all electrical penetrations are sealed. Factory-built mini homes typically have better air sealing than site-built homes because the walls are assembled in controlled conditions, but the foundation connection and any site modifications must maintain this air barrier continuity.

Before purchasing a mini home, verify that the manufacturer provides documentation showing the wall assembly meets NB Building Code thermal requirements. Some lower-cost mini homes still use 2x4 construction with R-12 insulation, which does not meet current code for new installations and will result in high heating costs and poor comfort in New Brunswick's cold winters.

The foundation and floor assembly also requires insulation — typically R-20 under the floor and R-17 for any basement or crawl space walls. Many mini homes use a frost-protected shallow foundation or full basement, both of which need proper insulation to prevent heat loss and frost damage in New Brunswick's 4-5 foot frost depth.

For mini home installation, ensure your contractor understands these code requirements and that the local building inspector will verify compliance before issuing occupancy permits. Mini homes that don't meet current insulation standards will be expensive to heat and may have difficulty qualifying for NB Power rebates or mortgage financing.

---

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

• 3Tone Construction Ltd
• Brunswick insulation & roofing
• Thirty Four Renovations
• Gionetterenovations
• moose luxury painting

View all contractors →