How tall can I build a retaining wall without a permit in New Brunswick?

In most of New Brunswick, retaining walls up to 4 feet (1.2 metres) in exposed height can typically be built without a building permit — but this threshold varies by municipality, and property line setbacks always apply regardless of height. Before starting any retaining wall project, it is worth making a quick call to your local building department to confirm the specific rules in your municipality.

The 4-foot rule reflects the NB Building Code's approach to retaining structures — walls below that height are generally considered low-risk residential landscape features, while walls at or above 4 feet retain significant soil mass and carry enough structural and safety risk to warrant permit review and, in many cases, engineered drawings. In cities like Fredericton, Moncton, and Saint John, the municipal building department follows this threshold closely. In rural NB under the jurisdiction of the Rural Service Commission (now Service New Brunswick), the same code threshold typically applies.

Height is measured as the exposed face of the wall — the distance from the finished grade at the base of the wall to the top of the wall. If your yard has a natural grade change of 6 feet but you are terracing it with two 3-foot walls separated by a level landing, each individual wall is under the permit threshold, though the cumulative effect on drainage and soil pressure still requires careful design. Some inspectors look at the total grade change being managed rather than individual wall heights, so check before assuming two short walls are automatically permit-free.

Even without a permit requirement, you are still responsible for building a wall that is structurally sound and does not damage neighbouring properties. A wall that retains waterlogged NB soil and collapses onto a neighbouring property or into a municipal right-of-way creates liability regardless of its height. Proper drainage behind any retaining wall — regardless of height — is non-negotiable in NB. A 3-foot wall with no drainage stone or weeping tile behind it can fail under the hydrostatic pressure that builds up from NB's spring thaw and heavy rain seasons.

Property line setbacks are separate from permit requirements. Most NB municipalities require retaining walls to be set back at least a few feet from property lines, and walls near driveways, sidewalks, or road rights-of-way have additional constraints. Check with your municipality before setting your layout.

If your grade change exceeds 4 feet or the wall will be near a structure, property line, or road, bring in a professional for an assessment. New Brunswick Concrete can connect you with experienced retaining wall contractors in the Moncton, Fredericton, Saint John, Miramichi, and Bathurst areas for a free consultation.