How much does a home addition cost per square foot in New Brunswick in 2026?

Single-storey home additions in New Brunswick cost $250–$400 per square foot fully built in 2026, while second-storey additions run $200–$350 per square foot. That wide range reflects real differences in foundation type, finish level, trade complexity, and the region of the province you're building in.

To put those numbers in practical terms: a 400 sq ft single-storey family room addition would run $100,000–$160,000 fully completed, including foundation, framing, roofing, windows, insulation, drywall, flooring, electrical, and interior finishes. A smaller 200 sq ft bump-out bathroom addition might land closer to $60,000–$80,000 once plumbing, tile, and fixtures are factored in alongside the structural work. Second-storey additions cost slightly less per square foot because the foundation already exists, but they often require structural engineering to confirm the existing walls, beams, and foundation can handle the added load.

What drives NB addition costs most dramatically is the foundation choice. A full poured concrete foundation and basement under a new addition adds $20,000–$40,000 compared to a frost-wall perimeter with a crawl space. Many NB homeowners choose a crawl space or slab-on-grade for additions to keep costs down, but both require careful detailing for NB's 4–5 foot frost depth — the footings absolutely must go below the frost line or you'll watch the addition heave and crack within a few years. A slab-on-grade addition without proper frost protection is one of the most common expensive mistakes NB homeowners make.

Finish level is the other major cost driver. Builder-grade finishes (standard trim, basic tile, stock cabinetry if applicable, LVP flooring) keep costs toward the lower end of the range. Mid-range finishes with engineered hardwood, pot lights, solid-surface countertops, and upgraded windows push toward the middle. Custom millwork, in-floor radiant heating, premium windows, vaulted ceilings, or exposed timber framing can push beyond $400/sq ft for smaller additions where fixed costs (engineering, foundation, roofing tie-ins) represent a larger share of the total.

NB renovation pricing runs 10–20% below Toronto or Vancouver for comparable work, primarily because of lower labour rates. But material costs are close to national averages since most building products are shipped into the province, so don't expect dramatic savings on windows, lumber, or insulation. Always get at least three quotes from local contractors and compare the scope carefully, not just the bottom line — a $250/sq ft quote that excludes electrical, finishes, or permit fees is not actually cheaper than a $310/sq ft all-in quote.

Budget a 15–20% contingency on any addition project. Once crews start digging footings or cutting into existing walls to connect the addition, surprises happen — undersized existing beams, buried utilities, deteriorated sill plates, or foundation work that needs more attention than expected. Older NB homes in particular tend to have framing that doesn't meet current span requirements, and the addition tie-in exposes that reality.

Need help finding experienced addition contractors in your area? New Brunswick Renovations can connect you with local professionals for free — and browsing the New Brunswick Construction Network directory is a good starting point for comparing contractors in your region.

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

• Gionetterenovations
• Thirty Four Renovations