A thin, dry, vertical crack in an older Aurora basement is usually a seal-and-monitor job. A horizontal, widening or leaking one needs its cause found first. Sealing from inside needs no heritage permit; exterior masonry does.
Older homes around Aurora's village core often have basements that have been moving, drying out and getting damp for a century. Most cracks you find are not an emergency, but the few that are look a lot like the harmless ones until you know what to check. This guide covers how to sort them, what sealing typically costs, and the one place Aurora's heritage rules can catch you out.
Sort the crack before you seal it
- Vertical, thin, dry: generally the less severe type. Foundation specialists describe vertical cracks as usually less serious than horizontal ones, though they can still let water in, so they are worth monitoring and sealing if needed.
- Horizontal: the one to take seriously. A horizontal crack can be a sign of a serious foundation problem, often pressure from soil or water pushing on the wall. Do not just seal it; have a foundation specialist or engineer look first.
- Wide, uneven or still growing: a crack where one side sits proud of the other, a wall that bows or tilts, or a crack that keeps widening points to movement, not shrinkage.
Before you do anything, mark each end of the crack with a pencil and a date, and photograph it next to a ruler. If it has not moved after a few months, that is useful evidence for whoever you call. If it has, tell them.
Epoxy, polyurethane, or something else
Contractors commonly inject two materials. Epoxy is rigid and is normally used on dry cracks where the aim is to bond the concrete back together. Polyurethane is a flexible foam that expands to fill a crack and is the usual choice for one that leaks. Neither is a cure for a wall that is still being pushed in. If a contractor quotes an injection for a horizontal crack, ask what they think is causing it and how they know it has stopped.
Typical cost ranges
These are general estimates from public Canadian price guides, not quotes, and Aurora prices will vary with access and how much is finished over the wall.
- Non-structural interior crack sealing: roughly $400 to $2,000 (HomeStars price guide).
- Interior epoxy or polyurethane injection of a single crack: commonly about $500 to $1,500.
- Exterior repair with digging and waterproofing: a Canadian foundation-repair guide puts this at about $3,000 to $5,500 per crack, because the soil has to be dug away first.
A finished basement adds cost, since drywall and paint have to come off and go back. Get at least two written quotes and ask whether a structural assessment is included.
Where Aurora's heritage rules apply
If your home sits in the Northeast Old Aurora Heritage Conservation District, the Town's Heritage Permit Guide matters. It lists interior work as not needing a heritage permit, except work that affects external appearance, and it also exempts repair of original elements using like materials. But "cleaning or re-pointing masonry" is on its list of work that does need one, and it recommends lime-rich mortar for older homes.
In practice: injecting a crack from the basement side is interior work. Repointing the stone or brick foundation outside, or re-parging it, is exterior masonry and is the thing to check first. The Town's Heritage Planning section is at 905-727-3123 ext. 4226 or planning@aurora.ca. The guide is dated 2017, so confirm current rules before you start. Heritage permits also do not replace a building permit. I could not find a Town page stating whether digging down and waterproofing needs a building permit, so ask the Town's building division before you excavate.
Quick answers
Can I seal a basement crack myself?
You can seal a small, dry, hairline vertical crack, but have anything wider, horizontal or moving looked at first. Sealing hides a symptom without fixing the cause.
Is a horizontal foundation crack serious?
Yes, treat it as possibly serious. Horizontal cracks can mean soil or water pressure is pushing the wall inward, so get a specialist or engineer to look before anyone seals it.
How much does it cost to seal a foundation crack in Ontario?
Roughly $400 to $2,000 for a non-structural interior crack, based on Canadian price guides. Digging down outside to repair and waterproof a crack costs several times more.
Does sealing a basement crack from the inside need a heritage permit in Aurora?
Interior work generally does not, since the Town's guide exempts interior work that does not affect external appearance. Repointing or re-sealing exterior masonry does need one, so call Heritage Planning first.
Which is better for a leaking crack, epoxy or polyurethane?
Polyurethane is the usual choice for a leaking, non-structural crack, and epoxy for a dry structural one. A contractor should tell you which they are using and why.
The short version
Seal what is small, dry and still. Get a second opinion on anything horizontal, growing or wet, and phone Heritage Planning before anyone touches the outside of a designated home. If you would rather have someone assess it and quote a fixed price, Rhodex can set that up.
Related reading
- More home repair guides for Aurora
- Exterior Repairs in Aurora's Heritage District: What Needs a Permit and What Doesn't
- How Do Building Permits Actually Work in York Region?
Not sure what's actually going on?
Every home is different, and home repair or renovation problems don't always match the textbook case. Describe your specific situation to Rhodex's AI Advisor and get a straight, honest answer — free, no obligation.
Ask the AI Advisor about your home repair or renovation question →