What permits are required for building a retaining wall in Moncton NB?

In Moncton, retaining walls over 4 feet (1.2 metres) in exposed height generally require a building permit, and walls of any height may need approval if they're near property lines, public rights-of-way, or in flood-prone areas along the Petitcodiac River. The City of Moncton's building inspection department administers permits, and requirements are based on the National Building Code of Canada as adopted by New Brunswick.

For walls under 4 feet in height, a building permit is typically not required in most residential zones, provided the wall doesn't retain a surcharge load (such as a driveway, building, or pool above the wall), isn't located in a designated flood zone, and meets required setbacks from property lines. Even without a permit requirement, all retaining walls must comply with the New Brunswick Building Code for structural safety. If you're building along a property line, confirm the exact boundary with a land survey to avoid encroachment issues — this costs $500-$1,500 in New Brunswick but prevents disputes and potential teardown orders.

Walls over 4 feet require a building permit and typically must include a structural engineer's stamp. The engineering requirement adds $500-$2,000 to your project cost but ensures the wall is designed to handle the soil pressure, hydrostatic pressure from New Brunswick's heavy rainfall (1,100-1,200mm annually), frost forces from 1.2-1.5 metre frost depth, and any surcharge loads. The permit application requires engineered drawings showing the wall design, footing depth, drainage plan, geogrid reinforcement specifications, and a site plan showing the wall's location relative to property lines and structures.

Moncton has specific considerations that may trigger additional requirements. Properties in flood zones along the Petitcodiac River and its tributaries fall under both municipal and provincial flood plain regulations. Retaining walls in these areas may need approval from the New Brunswick Department of Environment and Local Government in addition to a city building permit. Fill placement in flood zones is regulated provincially, so any wall that involves adding fill material may face additional scrutiny and requirements.

The permit application process in Moncton typically takes 2-4 weeks. Submit your application (including engineered drawings for walls over 4 feet) to the building inspection department with the applicable fee, which is generally calculated based on project value. You'll need to show proof of property ownership or authorization, a site plan, construction details, and drainage plans. Inspections are required at the footing/base stage (before backfilling) and upon completion.

Practical advice for Moncton retaining wall projects: even for walls under 4 feet that don't require a permit, hire a contractor experienced with NB conditions who understands proper base preparation for frost depth, backfill drainage (a perforated pipe in gravel behind the wall is essential), and material selection for freeze-thaw durability. Many homeowners discover during construction that their "3-foot wall" actually needs to be 5 feet once proper grading is factored in, pushing them into permit territory — so measure carefully before committing to a plan.

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