Poured concrete retaining wall vs concrete block wall in NB — which is better?

For walls over 3 feet high in New Brunswick, poured concrete is generally the stronger and more durable choice — but concrete block (CMU) walls are a cost-effective, practical alternative when properly reinforced and footed below the frost line. For walls under 3 feet, the difference in performance is minimal and budget or aesthetic preference should drive the decision.

Poured concrete walls are monolithic — there are no joints, seams, or mortar lines for frost and water to exploit. A properly formed and poured concrete retaining wall with rebar and a below-frost-line footing will handle NB's 4-5 foot frost depth, the lateral pressure from saturated spring soil, and 150+ annual freeze-thaw cycles better than virtually any other material. Poured walls are the preferred choice for walls over 4 feet, walls near structures or property lines, and walls retaining heavy clay soils common in the Fredericton and Saint John River valley areas. The disadvantage is cost and complexity — poured walls require forming, which takes time and skill, and large pours require a concrete pump and an experienced crew. Budget $25-$50 per linear foot per foot of height.

Concrete block (CMU) walls — hollow-core concrete masonry units filled with grout and vertical rebar — are structurally competitive with poured walls when properly built. The blocks are faster to work with than forms, can be laid by a smaller crew, and adapt more easily to irregular terrain. For walls in the 3-5 foot range on residential properties in Moncton, Dieppe, Riverview, and Saint John, a CMU wall with a proper footing and reinforcement is a legitimate, durable choice. The mortar joints and block interfaces are the potential weak points over decades of NB freeze-thaw cycles, but quality construction and a good waterproofing membrane on the retained side mitigate this risk. Budget $20-$40 per linear foot per foot of height.

The key factors favouring poured concrete:

• Wall height over 4 feet


• Clay-heavy or poorly draining soils


• Wall supporting a structure or heavy surcharge load


• Irregular or complex geometry where forming and pouring is actually simpler


• Coastal NB locations where salt air and moisture exposure are higher

The key factors favouring CMU:

• Walls in the 2-4 foot range


• Tight access where ready-mix trucks or pumps cannot easily reach


• Stepped or terraced designs with changing heights


• Budget constraints where CMU saves 15-25% over poured

Both options require the same commitment to frost-depth footings, drainage stone and weeping tile on the retained side, and proper waterproofing on the back face of the wall. Skimping on any of these elements will cause either wall type to fail eventually in NB conditions.

Browse retaining wall contractors serving communities across New Brunswick through the New Brunswick Construction Network directory at newbrunswickconstructionnetwork.com.