What is the difference between a poured concrete and block foundation in NB?

In New Brunswick today, poured concrete foundations are the clear industry standard for new residential construction — they are stronger, more watertight, and better suited to NB's frost and soil conditions than concrete masonry unit (CMU) block foundations. Block foundations were common in NB homes built before the 1980s, and many still exist throughout Moncton, Fredericton, Saint John, and the surrounding areas, but contractors rarely install new block foundations for residential basements.

Poured concrete foundations are cast in place using plywood, aluminum, or ICF forms filled with ready-mix concrete. Because the wall is monolithic — one continuous pour — there are no mortar joints, no voids, and no planes of weakness. A properly poured and reinforced concrete wall resists lateral soil pressure, frost heave, and water infiltration far better than a mortared block wall. Poured walls can also be formed to include window bucks, utility penetrations, and complex shapes in a single operation.

Concrete block (CMU) foundations are built course by course using hollow concrete blocks mortared together. The mortar joints are the weak point — mortar can crack and deteriorate over time, especially in NB's freeze-thaw environment, creating pathways for water infiltration. Block walls also have hollow cores that, if not fully grouted and reinforced with vertical rebar, can be structurally weaker than a comparable poured wall. Older NB block foundations commonly develop lateral pressure cracks, stair-step cracks along mortar joints, and water infiltration through the joints.

If you have an older block foundation in your NB home, it is not automatically a problem — millions of block-foundation homes perform fine for decades with proper maintenance. But watch for stair-step cracking, horizontal cracking, efflorescence (white mineral deposits on the block surface indicating water movement), and any signs of inward lean or bowing. These are signals to call a foundation specialist.

Parging — a cement-based coating applied to the exterior and sometimes interior of block walls — is commonly used to improve the appearance and weather resistance of block foundations. Parging costs $5-$10 per square foot and is a reasonable maintenance measure, but it does not fix structural issues.

Cost comparison for new construction: Poured concrete and block foundations are comparable in cost for new NB residential construction — both typically range from $15,000-$40,000 for a full basement depending on size and complexity. Given that poured concrete is superior in almost every performance category, it is the preferred choice for any new build. New Brunswick Concrete can connect you with foundation contractors in your area.