What is the best foundation repair method for old NB homes?

Old New Brunswick homes — particularly those built before 1970 — often have foundations made from stone and mortar, poured concrete that predates modern admixtures and reinforcement standards, or hollow concrete block (CMU). The best repair method depends entirely on what type of foundation you have, what problems it is showing, and what your goals are for the home.

The most common foundation types in older NB housing stock, and their repair approaches, break down as follows.

Stone rubble foundations (common in NB homes built before the 1940s) are the most labour-intensive to repair. These were built by stacking field stones with lime or Portland cement mortar, sometimes mud mortar on very old structures. Problems include deteriorated mortar joints (called repointing or tuckpointing — removing the old mortar and packing in new mortar), shifted or fallen stones, and chronic water infiltration through the porous stone and mortar. For stone foundations being retained as-is, repointing with a mortar that matches the original lime-rich mix is critical — Portland-heavy modern mortar is too rigid and will accelerate stone damage. In many cases, a failing stone foundation under a house that needs other significant renovation is best addressed by underpinning: excavating beneath sections of the existing foundation and installing a new poured concrete footing and stem wall. This is major structural work requiring engineering.

Early poured concrete foundations (common from the 1940s through the 1970s) often lack reinforcing steel, used lower-strength mixes by modern standards, and have minimal or no waterproofing. Vertical cracks from concrete shrinkage are universal in these foundations. The repair approach depends on whether cracks are leaking (polyurethane foam injection to stop water) or structural (epoxy injection). Widespread surface deterioration on the wall interior can be addressed with crystalline waterproofing compounds (products like Xypex or Krystol that penetrate the concrete and form crystals that block water pathways).

Hollow concrete block foundations are particularly problematic in NB because water infiltrates through the mortar joints, enters the hollow cores of the blocks, and can move horizontally throughout the wall. Standard crack injection does not work well on block — the interior treatment approach (installing a drainage channel system along the interior base of the wall, connected to a sump pump) is often more effective and less costly than attempting exterior excavation and waterproofing on an older block foundation.

The most important first step for any old NB foundation is a professional assessment — not just a waterproofing company salesperson, but ideally a structural engineer or an experienced contractor who works specifically on foundation repair. Diagnosing why the foundation is failing (water pressure? frost heave? settlement? deteriorated mortar?) determines the right repair. Applying the wrong repair — interior drainage on a wall with structural movement, or crack injection on a block foundation — wastes money.

New Brunswick Concrete can connect you with foundation specialists in Moncton, Fredericton, Saint John, and across NB who have experience with the province's older housing stock.