How wide should footings be for a two-storey house in New Brunswick?

For a typical two-storey wood-frame house in New Brunswick, residential strip footings are commonly 20-24 inches (500-600 mm) wide and 10-12 inches (250-300 mm) thick, though the exact dimensions must be calculated based on the building load and the soil's bearing capacity at your specific site. Footing sizing is not a guessing game — undersized footings lead to settlement, and NB building inspectors will catch this during the footing inspection before concrete is poured.

How footing width is determined: The width of a footing depends on two factors — the load it must carry (the combined weight of the structure, contents, and live loads like snow) and the allowable bearing pressure of the soil beneath it (how much load the soil can support per square foot without compressing or failing). Load is divided by allowable bearing capacity to get the required footing area.

For NB residential construction, soil bearing capacity is commonly assumed at 75-100 kPa (1,500-2,100 PSF) for typical glacial till soils in the absence of a formal geotechnical investigation. Soft clay or silt — found in some areas of Moncton, Dieppe, and along river valleys — can have much lower bearing capacity (as low as 50 kPa), requiring wider footings. Dense gravel or till can support 150+ kPa, allowing narrower footings. A soil test eliminates guesswork and is worth doing on any significant new build.

NB Building Code requirements: The National Building Code of Canada (adopted in NB) provides prescriptive footing width tables for residential construction. For a two-storey house with a basement on soil with 75 kPa bearing capacity, strip footings under exterior walls are typically 24 inches (600 mm) wide. Interior bearing wall footings and column footings are sized proportionally to the load they carry.

Footing depth is non-negotiable in NB. Regardless of width, all structural footings must extend below the frost line — a minimum of 4 feet (1.2 metres) below finished grade in southern NB (Moncton, Saint John, Fredericton) and 4.5-5 feet in northern NB (Bathurst, Edmundston, Miramichi). Frost heave on a shallow footing can lift a corner of your house, causing significant structural damage.

Footing concrete specifications: Use a minimum 25 MPa concrete for footings. Place footings on undisturbed soil or properly engineered structural fill — never on disturbed, organic, or frozen ground. Rebar reinforcement (typically two #15M bars running continuously) is standard in NB residential footings to provide tensile strength against differential settlement. Your building permit drawings will specify the required footing dimensions for your specific project.