What is the minimum footing depth for a residential home in Saint John New Brunswick?

In Saint John, all residential footings must extend a minimum of 1.2 metres (4 feet) below finished grade — this is the frost line depth required under the National Building Code of Canada 2020, which New Brunswick officially adopted effective May 1, 2025.

That said, Saint John is a bit of a special case worth understanding. Because Saint John sits on the Bay of Fundy coast, the frost penetration depth is slightly shallower than inland areas like Fredericton or Woodstock — but the NBC's 1.2m minimum still applies, and local inspectors will hold you to it. In practice, many experienced Saint John contractors will dig to 1.4–1.5m in areas with poor soil drainage or known frost heave issues, particularly in the West Side, East Side, and North End where older clay-heavy soils are common.

Your building permit comes from the City of Saint John — specifically the Growth & Community Services department at (506) 658-2835 or through saintjohn.ca. They'll review your foundation drawings as part of the permit process, and a building inspector will verify footing depth before you're allowed to pour concrete. Don't skip that inspection — if you pour without sign-off, you may be required to excavate and expose the footings again.

A few Saint John-specific factors that can affect your footing design beyond just depth:

• Bedrock: Parts of Saint John — especially the Peninsula and some hillside areas — have bedrock very close to the surface. If you hit solid bedrock before reaching 1.2m, your engineer can design footings directly on rock (which is actually excellent bearing material), but this requires documentation and engineer sign-off.
• Soil bearing capacity: Saint John's older neighbourhoods have variable fill and disturbed soils. A geotechnical assessment ($1,500–$4,000) is worth considering for any new build or major addition.
• Flood risk: Low-lying areas near the harbour and Reversing Falls are subject to tidal and storm surge influence — check provincial flood risk maps before finalizing your foundation design.

Footing sizing is the other half of the equation. Depth gets you below frost, but width determines load distribution. A standard residential footing is typically 24 inches (600mm) wide and 10–12 inches (250–300mm) thick for a single-storey home, wider for two-storey. Your structural drawings — required as part of your permit application — will specify the correct dimensions for your soil conditions and building loads.

This is firmly in licensed contractor and engineer territory. A qualified foundation contractor will know Saint John's soil conditions intimately and will work directly with the city's building inspection team throughout the process.

Browse foundation and excavation contractors in our directory at New Brunswick Construction Network — newbrunswickconstructionnetwork.com/directory