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Homeowners usually notice the symptoms indoors before they look at the foundation: doors that start to stick, cracks opening above windows, floors that slope toward one side of the house. Outside, a stair-step crack in brick or block, a gap at a window frame or a porch pulling away can point to the same movement. Some movement is old and has stopped; some is still going on. Telling the two apart is a job for a structural engineer, not for the company that will sell the repair.
This page covers the signs of structural movement, what an engineer's assessment involves, what causes foundations to move, the main repair methods in general terms, permits and Quebec's pyrrhotite program. None of it is do-it-yourself work: digging beside footings or jacking part of a house can cause a collapse.
Signs of structural foundation movement: stair-step cracks, sticking doors and sloping floors
A single sign rarely proves much, since houses move slightly with the seasons. A pattern of several signs, or signs that keep getting worse, deserves an engineer's attention.
- Stair-step cracks that follow the mortar joints of a block or brick wall, especially when they are wider at one end.
- Horizontal cracks along a basement wall, sometimes with the wall bowing inward under pressure from the soil outside.
- Doors and windows that stick, swing open on their own or show uneven gaps, where they used to close properly.
- Floors that slope or bounce, and gaps opening between the floor and the baseboards or the bottom of interior walls.
- Diagonal cracks in drywall or plaster running from the corners of doors and windows, and coming back after being patched.
- A chimney, porch, stairs or attached garage pulling away from the house, or brick veneer separating from the wall behind it.
- A corner or section of the house that has visibly dropped, with cracks wider at the top or at the bottom.
Why a structural engineer should assess foundation problems before any repair
A structural engineer looks at the house as a whole: the pattern of cracks inside and out, floor levels measured across the house, the type of foundation and soil, drainage, nearby trees and the history of the building. When the cause isn't obvious, they may suggest monitoring through a full year of seasons, a soil investigation by a geotechnical engineer or a test pit beside the footing. You should come away with a written report that explains the cause, says whether the movement is still active and describes the repair needed, if any.
Hiring the engineer yourself, rather than relying on an assessment from a company that sells piers or underpinning, keeps the diagnosis separate from the sale. Engineering is regulated by each province. In Quebec, the Ordre des ingénieurs du Québec names an opinion on the consequences of a crack in a foundation wall among the services an engineer provides, and its member directory shows whether an engineer is in good standing; in Ontario, Professional Engineers Ontario keeps a public directory of licence holders. The same engineer can design the repair and review it on site as the work proceeds.
What makes a foundation settle, heave or deteriorate
- Shallow footings: porches, additions and older extensions built without footings deep enough to escape frost can heave in winter and drop in spring.
- Soft or poorly compacted fill: soil placed during construction that keeps settling under one part of the house.
- Water softening or washing out the soil: a broken drain, a leaking pipe or roof water pouring down at one corner year after year.
- Clay soils that shrink as they dry, during long droughts or where large trees draw moisture from beneath the footing.
- Aging materials: rubble-stone foundations with crumbling mortar, and block walls weakened by decades of water and frost.
- Concrete attacked by reactive minerals: in some Quebec regions, pyrrhotite in the aggregate has caused foundations to crack and break down.
- Changes nearby: excavation next door, a new addition or heavy equipment working close to an existing foundation.
Foundation repair methods: underpinning, piers and piles, and wall bracing
The engineer's report sets the method, and a qualified foundation contractor carries it out. These are the main families of repair, described in general terms. Lowering a basement also relies on underpinning, but that is a renovation choice rather than a repair.
- Underpinning: extending the foundation down to deeper, firmer soil by excavating and pouring new concrete beneath the existing footing in short, alternating sections.
- Steel piers or piles: driven or screwed into the ground beside the foundation until they reach firm soil or rock, then fastened to the footing with brackets to carry the load and sometimes bring it back toward level.
- Wall bracing: steel beams, anchors or reinforcing straps that hold a bowed or cracked basement wall against soil pressure.
- Partial rebuilding: taking down and rebuilding a section of block or stone wall that is too far gone to reinforce, with the house supported temporarily.
- Slab repairs: filling voids under a settled basement floor or replacing sections that have heaved or sunk.
- Drainage and soil corrections: fixing the water conditions that caused the movement, often an essential part of the structural repair itself.
Building permits and engineering requirements for foundation repair and underpinning
Structural foundation work generally needs a building permit. In Toronto, for example, underpinning an existing house requires one, and the city calls for design and on-site review by a professional engineer in certain cases, including where the soil is clay or silt or the new footings go below a neighbouring building's footings. Even when those conditions don't apply, Toronto requires at minimum testing and reports by a professional engineer at the first and last stages of construction to pass inspections.
Other municipalities, including Quebec cities and Montreal's boroughs, set their own requirements and can ask for plans sealed by an engineer, so check with your permit office which documents they need. Work beside a shared wall or a neighbour's footing also raises questions of access and responsibility that should be settled in writing before any digging starts.
Quebec's pyrrhotite program for damaged foundations
The Société d'habitation du Québec runs a program for owners of residential buildings whose foundations are damaged by pyrrhotite, a mineral found in some concrete aggregate that can make foundations crack and break down. It has supported expert assessments to detect pyrrhotite and, in municipalities that have put measures in place against the problem, work such as replacing the foundations and restoring the basement rooms.
The work component has been suspended since April 1, 2025, pending new funding, and no new applications are being accepted for now. If you suspect pyrrhotite, check the program's current status with the Government of Quebec and your municipality or MRC before planning around it, and have an engineer confirm the diagnosis.
Foundation Repair: frequently asked questions
Is a stair-step crack in my foundation serious?
It can be. Stair-step cracks in block or brick often mean one part of the foundation has moved relative to another. If the crack is wide, uneven, growing or comes with sticking doors or sloping floors, have a structural engineer look at it.
Should I call a foundation contractor or a structural engineer first?
For signs of structural movement, start with an independent structural engineer. Their report tells you whether a repair is needed and which one, and gives every contractor you ask for a quote the same scope to price.
Can a sinking foundation be lifted back to level?
Sometimes, partly. Piers can lift a settled section, but lifting can crack finishes, and the engineer may decide stabilizing the house where it is does less harm. The main goal is to stop the movement.
How can I tell whether foundation movement has stopped?
By watching over time. Marking the ends of cracks, dating photos and noting when doors start or stop sticking across a full year shows whether things are changing. An engineer may set up more precise measurements if needed.
Can I install piers or underpin a foundation myself?
No. Excavating under or beside a footing, jacking a house and pouring new footings can cause sudden collapse, and the work needs an engineer's design, a permit and an experienced crew. Your part is monitoring and keeping water away from the foundation.
Will a foundation repair affect selling my house?
A known foundation problem should be disclosed to buyers, and an unexplained one tends to worry them more than a documented repair. Keep the engineer's report, the permit, the final review and any warranty on the work together to show the problem was handled properly.
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Written by the LokalMatch editorial team. Reviewed by Zubair Afzal on September 10, 2026. How we write and check our guides