What type of retaining wall is best for New Brunswick soil?

For most New Brunswick residential applications, poured concrete and precast concrete block (CMU) retaining walls offer the best combination of strength, frost resistance, and longevity in NB soil and climate conditions. The right choice depends on your wall height, soil type, drainage situation, and budget.

NB soils vary significantly by region. The Saint John River valley and areas around Fredericton, Oromocto, and Miramichi have clay-heavy soils that retain water and exert high lateral pressure against retaining walls — especially during spring thaw when saturated soil can triple the pressure on a wall compared to dry conditions. Sandy, well-drained soils in parts of Moncton and the Moncton area are more forgiving but still subject to frost heave. Any retaining wall in NB must be designed for the worst-case condition: waterlogged, frost-susceptible soil at the end of a wet spring.

Poured concrete walls are the strongest option and the best choice for walls over 3 feet high, walls retaining clay soils, and walls near structures. A properly reinforced poured concrete wall with a below-frost-line footing (4 feet minimum in southern NB, 4.5-5 feet in the north) will handle NB freeze-thaw cycles and saturated soil pressures better than any other material. The monolithic structure has no joints that can be exploited by frost heave. Cost runs $25-$50 per linear foot per foot of height.

Concrete block (CMU — concrete masonry unit) walls are a cost-effective alternative for walls up to 4-6 feet with proper footing and reinforcement. Interlocking hollow-core blocks filled with concrete and vertical rebar create a strong, flexible wall system. They are easier to build on irregular terrain than formed poured walls and are a common choice for residential retaining applications in Moncton, Dieppe, and Saint John. Cost runs $20-$40 per linear foot per foot of height.

Segmental retaining wall blocks (Allan Block, Unilock, and similar systems) are gravity-mass walls suitable for walls under 3 feet in NB without a permit. They are popular for landscape terracing, garden beds, and low grade changes. They rely on their own weight and batter (backward lean) for stability rather than footings and reinforcement. For low walls, they perform well in NB — but they should never be used for walls over 3 feet without engineering review, as the saturated soil pressures during spring thaw in NB easily exceed what an un-engineered segmental wall can resist.

Timber and railroad tie walls are the least suitable for NB conditions. Wood rots in NB's wet climate, frost cycles work the posts out of alignment over time, and these walls typically need replacement every 10-20 years. They are acceptable for very low garden terracing but should not be used for any structural soil retention application.

For any wall over 3 feet in NB, have a concrete professional assess your specific site, soil, and drainage conditions. New Brunswick Concrete can connect you with experienced retaining wall contractors in Fredericton, Moncton, Saint John, Bathurst, Miramichi, and across the province.