Can I pour sonotube footings myself for a deck in New Brunswick?

Yes, pouring sonotube footings for a residential deck is one of the more manageable DIY concrete tasks -- but NB's frost depth requirements make getting the depth right absolutely non-negotiable.

Sonotubes are cardboard tube forms available in 8-inch, 10-inch, and 12-inch diameters from NB building supply stores. For a typical deck with 4x4 or 6x6 posts, the process involves digging holes to below the frost line, placing the sonotube, mixing and pouring concrete, and embedding a post base hardware anchor while the concrete is wet. It sounds simple, and for small decks with two to four posts, it genuinely is achievable for a competent DIYer.

The most critical rule in New Brunswick: your sonotube footing holes must reach a minimum of 4 feet below finished grade in southern NB (Moncton, Fredericton, Saint John, Dieppe, Riverview) and up to 4.5-5 feet in northern NB (Bathurst, Miramichi, Edmundston). Frost heave is not theoretical -- a footing that sits above the frost line will move every winter, and after a few cycles your deck will be visibly out of level, with connections pulling apart and boards cracking. There are no shortcuts on depth.

For a deck that requires a building permit (most decks attached to the house do), your local building inspector will specify the footing diameter and depth. In Fredericton and Moncton, the municipality will typically inspect footing holes before you pour, so do not skip that step. For a small freestanding deck under 108 square feet in most NB municipalities, permits are often not required, but the frost depth requirement still applies.

Materials for a typical deck footing: one or two 30 kg bags of Quikrete or Bomix per tube, plus a post base anchor embedded at the correct height. For eight sonotubes you are looking at $80-$150 in materials if you mix by hand. Rent a one-man power auger from a NB equipment rental shop for around $100-$150 per day -- digging 4-foot holes in NB's rocky glacial soil by hand is brutal work.

Use the water amount specified on the bag, never more. Wet, sloppy concrete in a footing has reduced strength and is more susceptible to freeze-thaw damage. If you are pouring in May or June (ideal timing), the concrete will cure fully within 7 days before any load is applied.

If your deck is large, elevated, or complex -- or if you are unsure about your soil conditions -- it is worth having a concrete professional assess and pour the footings. The foundation of your deck is not the place to gamble. New Brunswick Concrete can match you with a local concrete professional for free if you want a quote on the footing work.