A thin, dry crack that is not growing is usually a seal-and-watch job in an older Unionville or Markham Village basement. A horizontal, widening or leaking one needs its cause found first. Interior sealing generally needs no building permit in Markham.
Unionville and Markham Village are among the oldest parts of the city, and many of the houses on their older streets have a foundation that has been through a very long run of wet springs and freeze-thaw winters. Cracks turn up when someone finally clears the basement shelves, or when a buyer's inspector does it for them. Most are not an emergency. This guide covers how to sort them, what Markham says about permits, where the heritage rules begin, and what sealing typically costs.
Sort the crack before you seal it
- Hairline, dry, vertical or diagonal: usually shrinkage in the concrete as it cured. Seal it if it bothers you, and otherwise note it and watch it.
- Up to roughly a quarter inch and damp at times: often minor settling. Worth sealing, because it lets in moisture and soil gas.
- Horizontal, stair-stepping through block joints, wider than about a quarter inch, or growing: treat it as a question for a foundation specialist or engineer, not a caulking gun. These widths are rules of thumb, not an engineering standard.
Pencil-mark each end of the crack, write the date, and photograph it next to a ruler. A wide crack that has not changed in years is less worrying than a hairline that appeared last month and keeps lengthening. If doors or windows upstairs have started sticking or a wall bows inward, skip the monitoring and call someone.
Check what your foundation is made of first
The age of the house changes the job. A foundation of poured concrete, concrete block, or older rubble stone or brick does not respond to the same repair. Injecting a crack suits poured concrete. A crumbling joint in a stone or brick wall is a masonry repair, and the mortar used matters: guidance on historic masonry from the U.S. National Park Service says new mortar should not be harder or less breathable than the original, because an overly strong mix can damage softer old material. If your basement wall is stone or old brick, ask any contractor what they would use and why before the first joint is touched.
Epoxy, polyurethane, and what neither one fixes
Contractors commonly inject concrete cracks from inside with one of two materials. Epoxy is rigid and is generally used on dry cracks to bond the concrete back together. Polyurethane is a flexible foam that expands into a crack and is the usual choice when it leaks. Neither fixes a wall that is still being pushed inward. If water keeps coming back after sealing, the cause is usually outside: grading that slopes toward the house, a downspout emptying beside the wall, or a failed exterior membrane. Sealing from inside treats the symptom, so ask what is causing the crack and how they know it has stopped.
What Markham says about permits
Markham's published list of work that does not need a building permit includes “interior damp-proofing basements” and “maintenance and repairs.” The same page lists “adding, removing or altering a structural wall or column” among the work that does. Anything more than sealing, such as underpinning or a new opening, is a different category, so ask any contractor who would pull the permit. The list is for general use and does not cover every case. Markham's Building Standards Department is at 905-475-4858.
Where the heritage rules start
Unionville and Markham Village are both Designated Heritage Conservation Districts, and individually designated properties elsewhere in the city are covered too. The City says that altering the exterior of any building in a district “requires a heritage review and approvals process,” and that you must contact the Building Standards Department for the necessary approvals before you begin (905-475-4870).
For a crack, the line is simple to state. Sealing it from inside the basement is interior work. Digging out the outside of the wall, re-coating or re-parging a visible foundation, or repointing stonework you can see from the street is exterior work. Call first, with the address, and ask whether the job counts as an alteration. You can also check whether your address is on the City's heritage register.
When the TRCA is worth a look
Much of Markham sits in the Rouge River and Don River watersheds, which the Toronto and Region Conservation Authority covers, and its regulated areas include valley corridors and floodplains. Markham planning reports routinely note that a TRCA permit is required for works inside such areas. Interior crack sealing is not the kind of work that triggers one, but excavating beside the foundation of a lot near a valley or river might. Check your address with TRCA before anyone digs.
What sealing typically costs
These are general estimates from public Canadian price guides, not quotes, and the guides do not agree with each other. Interior injection of a single crack is commonly listed at about $500 to $1,500, whether epoxy or polyurethane. Exterior repair that involves excavation and waterproofing is listed at several thousand dollars per crack, and larger, structural or multi-crack jobs are priced after an assessment. Get a written quote that names the material, the number of cracks and the warranty, and get more than one.
Quick answers
Can I seal a small basement crack myself in an older Markham home?
Yes, a thin, dry crack that is not growing can be sealed from inside. Wider, leaking, horizontal or growing cracks should be looked at by a foundation specialist or engineer first.
Do I need a permit to seal a basement crack in Markham?
Usually not for interior sealing. Markham's published list of work that does not need a building permit includes interior damp-proofing of basements and maintenance and repairs, but confirm your exact scope with the city.
Do the Unionville and Markham Village heritage rules cover basement crack sealing?
Not for work done entirely inside. They cover altering the outside of a building, which includes digging out and re-coating a visible foundation wall, so call the city before that kind of job.
How much does foundation crack injection cost in Markham?
Public Canadian price guides put interior injection of one crack at roughly $500 to $1,500. These are general estimates for the area, not quotes.
Does the TRCA matter for a crack repair in Markham?
Only if the work is outside and near a valley, river or other regulated land. Interior sealing is not what a conservation authority permit is about, but check before digging.
Seal what is small, ask about what is not
Most basement cracks in older Markham houses are the small, dry kind, and sealing them is a quick, inexpensive job. The skill is in telling them apart from the ones that are telling you something about the wall, and in knowing when a job has crossed from the basement to the outside of a heritage district house. If you want a person to look at yours, describe it here.
Related reading
- More home repair guides for Markham
- All Rhodex services: get a fixed price
- Exterior Repairs on a Main Street Unionville Heritage Home: What Needs Sign-Off
- Drywall and Plaster Repair in Markham: An Older Unionville Home vs. a Newer Build
- Sealing a Basement or Foundation Crack in Thornhill
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