How far apart should deck posts be spaced in New Brunswick?

Deck posts in New Brunswick should typically be spaced 6 to 8 feet apart, with the exact spacing determined by the beam size, joist span, and the loads the deck must support. This range applies across the province regardless of whether you are building in Moncton, Fredericton, Saint John, or any other community, because post spacing is a structural engineering question governed by the National Building Code of Canada and the lumber span tables it references.

The 6-to-8-foot range works as a general planning number for most residential decks, but the actual spacing depends on your specific beam configuration. A doubled 2x8 beam can safely span about 6 feet between posts when supporting joists with a typical 8-to-10-foot span. Step up to a doubled 2x10 beam and you can extend post spacing to approximately 8 feet under the same joist load. A tripled 2x10 or a doubled 2x12 beam can push slightly beyond 8 feet in some configurations, but going much beyond 8-foot spacing on a residential deck is uncommon and requires an engineer's stamp in most jurisdictions.

New Brunswick's climate introduces a load factor that directly affects these calculations. The province's snow load requirements are significant. Depending on your location, ground snow loads range from about 2.5 kPa in the southern coastal areas around Saint John to 3.5 kPa and higher in the northern interior near Edmundston and Campbellton. Decks must be designed to support these snow loads in combination with the dead load of the structure and the live load of occupants and furniture. Higher snow loads generally push post spacing tighter, toward the 6-foot end of the range, because the beams must carry more cumulative weight.

The post spacing layout for a typical 14-by-20-foot deck in New Brunswick illustrates how this works in practice. The 20-foot dimension usually runs parallel to the house, with the joists spanning the 14-foot depth. You would have a beam running the 20-foot length at the outer edge of the deck, supported by posts. With doubled 2x10 beams, you would place posts at roughly 6.5 to 7 feet apart, resulting in three posts along that beam plus one at each end, for a total of four posts on the outer beam. If the joist span is longer than about 10 feet, you may need an intermediate beam with its own set of posts, effectively doubling the total footing count.

Each post sits on a footing that must extend below the local frost line. In southern New Brunswick cities like Moncton, Saint John, and Fredericton, that means footings to 1.2 metres deep. In northern areas like Bathurst, Campbellton, and Edmundston, footings must reach 1.5 metres. Sonotube forms with a minimum 10-inch diameter are standard, filled with concrete and fitted with post brackets. Helical piles at $200 to $500 each are an alternative that avoids concrete altogether and works well in the rocky glacial soils found in many parts of the province.

Post size matters alongside spacing. For most residential decks up to about 10 feet in height, 6x6 pressure-treated posts are standard. Some builders in New Brunswick still use 4x4 posts for short decks under 4 feet tall, and while this can meet code for very low structures, 6x6 posts provide substantially better resistance to lateral racking forces from wind and snow loads. Given the minimal cost difference, 6x6 is the better default choice for New Brunswick decks.

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