Restoration Register

Heritage foundation repair in Ontario

A rubble stone foundation is built to breathe. The standard basement waterproofing package, cement parge inside, membrane outside, sealed slab, traps water in the wall and drives it upward into the masonry above, where it causes far more expensive damage than the damp basement ever did.

Pre-1900 Ontario buildings sit on rubble stone, fieldstone or early brick foundations laid in lime mortar, and the failure pattern is consistent: mortar washed out of the joints, a rotted sill plate above, a wall bulging under lateral load, and earlier cement parging holding moisture in. Correct repair is repointing in lime mortar, rebuilding sections that have lost their bond, replacing sill plates with the building jacked and supported, and using breathable parge and finishes throughout. Underpinning to gain headroom is a structural job needing an engineer's design and a contractor who has worked under a standing heritage building. Only three specialists are verified in this category, and heritage masons cover much of the same work.

What to ask before you hire

  1. What will you point and parge with? Standard cement holds water in the wall and the masonry above pays for it.
  2. Is an engineer involved? Underpinning, and any wall that is bulging or moving, needs a design rather than a contractor's judgment.
  3. What is the shoring plan, and how long will the building sit on it? Ask to see it before work starts.
Grant funding

Foundation work is usually eligible where it is conservation rather than new basement space. Repointing and stabilisation typically qualify, while excavating a new basement typically does not. Confirm the scope with heritage staff before applying.

Across Ontario

Region pages

All heritage service pages · Grants by municipality