Do I need a permit for a retaining wall in Moncton NB?

In Moncton, retaining walls under 4 feet (1.2 metres) in exposed height generally do not require a building permit, but walls over 4 feet do — and walls over 4 feet typically also require engineer-stamped drawings. The height threshold is the critical factor, and it is measured from the bottom of the footing to the top of the wall, not just the visible above-grade height.

The City of Moncton follows NB building code requirements for retaining structures. Walls under 4 feet are considered minor landscape structures that fall outside the building permit threshold for most residential properties. That said, even permit-exempt walls must still be set back from property lines — typically a minimum of 0.6 metres (2 feet) from the property line in Moncton's residential zones, though your specific zoning may have different requirements. Always confirm setbacks with the City of Moncton Planning and Development department before starting work.

For walls over 4 feet, the permit process requires a site plan showing the wall location, and most building inspectors in Moncton will require stamped engineering drawings for walls in this height range. The engineering requirement exists because taller retaining walls must resist substantial lateral soil pressure, hydrostatic pressure from groundwater, and the unique frost heave forces that NB winters generate. A 5-foot concrete retaining wall that fails does not just fall over — it can release a significant volume of saturated soil, potentially damaging neighbouring property and creating a safety hazard.

Frost depth considerations are critical for retaining wall footings in Moncton. The Moncton area requires footings at least 4 feet (1.2 metres) below finished grade to get below the frost line. A retaining wall footing installed above the frost line will heave in winter, tilt, and eventually fail. This means a 4-foot retaining wall in Moncton requires excavation down to roughly 8 feet total (4 feet of footing depth plus 4 feet of wall height) — a significant and professional undertaking.

For poured concrete retaining walls in Moncton, budget approximately $3,000-$6,000 for a standard 30-linear-foot wall at 3 feet of exposed height, or $40-$75 per linear foot per foot of height for engineered walls over 4 feet. These costs include footing excavation, forming, reinforcement, concrete, and backfill with drainage aggregate.

Always include proper drainage behind any retaining wall — perforated pipe at the base of the wall connected to daylight, surrounded by clear stone. Without drainage, hydrostatic pressure builds behind the wall and dramatically increases the risk of failure, especially during NB's spring thaw when saturated soil becomes heavy and mobile. New Brunswick Concrete can match you with experienced local contractors who build code-compliant retaining walls in Moncton and the greater Dieppe and Riverview area.