A small round wet spot partway up a poured wall is almost never a crack. It is a form-tie hole — and it is sealed differently.
What is a tie rod hole and why is it leaking? When a poured concrete foundation is formed, steel ties span the gap between the two form walls to hold them at the correct thickness. After the forms come off, the tie ends are snapped away and the steel remnant stays buried in the wall. Each tie leaves two holes — one on each face — and on the inside face that hole is typically a cone-shaped recess about 25 mm wide by 37 mm deep. Builders plug the mouth of that recess with mortar. Decades later, water finds the gap between the concrete and the steel remnant behind the plug, and appears as a coin-sized wet spot mid-wall with a narrow streak running down to the floor.
Sealed by polyurethane injection into the void itself — not patched over the surface. Typically from $150 per hole, with volume pricing on multiples.
The shape of the water tells you what you are looking at, before anyone opens a wall.
Water starts at one discrete spot partway up the wall, with a narrow streak below it and dry concrete above and beside it. Often there is a rust-brown stain under the opening, and often the same thing repeats on a regular grid across the wall.
Water tracks along a continuous line — usually vertical or diagonal, frequently running from a window corner or full height. That is a foundation crack, and it is injected along its whole length.
Water pooling where the wall meets the floor with no wet streak above it is under-slab pressure at the wall–floor seam. Injection will not fix that one, and we will tell you so rather than sell you a repair that cannot work.
The regular, repeating pattern is the strongest single clue. Cracks do not arrive in a grid; form ties do.
Poured foundation walls are built between two form faces held apart by steel ties. Snap ties — the light-forming type used in almost all residential work — carry a plastic cone at each end that sets the wall thickness and holds the form off the concrete. When the forms are stripped, the cone is twisted off and the tie is snapped at a deliberate weak point, the breakback, set about 25 mm (1 in.) behind the face on a standard tie. Flat-bar ties break back much shallower — roughly 6 mm (¼ in.).
Two things follow from that, and neither appears on any competitor page we could find:
The interior hole left by a cone snap tie is a recess roughly 25 mm across and 37 mm deep. Behind the bottom of that recess sits the snapped end of the steel tie. That geometry is the whole story of why these leak.
Three things work against that plug over thirty years.
A structural engineer who has examined roughly 400 residential foundations puts it bluntly: water will almost always find its way through the interface between the concrete and whatever form-tie material was used. The wall is not monolithic at that point — there is a boundary, and boundaries leak.
This is the part homeowners find surprising. Mortar troweled into the face of a 37 mm-deep cone bridges the opening. It does not necessarily fill the annulus around the tie remnant behind it. Manufacturer repair procedures implicitly agree — Xypex’s published method insists the void first be chipped out to a clean, straight-sided U shape roughly 25 mm by 37 mm before anything is packed into it, and specifically rules out a V-shaped void. This mechanism is our reading of field evidence and manufacturer procedure rather than a published standard, and we would rather say so than overstate it.
Corrosion products occupy several times the volume of the steel they replace — the US Federal Highway Administration puts ferric oxide at roughly three times. That is what produces the rust-brown stain below a leaking hole, and it is why the gap tends to widen rather than heal. On residential foundation walls this is normally a water and cosmetic problem, not a structural one; engineers generally regard an embedded tie remnant in ordinary concrete as benign. We are not going to tell you your house is falling down because a tie is rusting.
Two different standards govern how deep a tie has to be buried, and houses get the lenient one.
| Document | Applies to | What it requires of form ties |
|---|---|---|
| ACI 301 — Specifications for Structural Concrete | Structural concrete | Embedded tie must terminate at least two tie diameters behind the face, and in no case less than 19 mm (¾ in.) |
| Ontario Building Code 9.15.6.3 — Form Ties | Part 9 housing | “All form ties shall be removed at least flush with the concrete surface.” |
| Ontario Building Code 9.13.2.4(2) — Preparation of Surface | Part 9 housing | Holes from form-tie removal to be “sealed with cement mortar or dampproofing material” before dampproofing |
To be fair about it: a flat tie breaking back 6 mm satisfies the OBC, and ACI 301 is not invoked for Part 9 houses. Nobody has broken a rule. But the Code assumes those holes get sealed from the outside, at construction, before the dampproofing goes on. It says nothing about a hole that starts leaking from the inside twenty-five years later — which is the situation you are actually in.
Article numbers above are quoted from the 2012 OBC with amendments. Part 9 was renumbered in the 2024 edition; the wording is materially unchanged but the numbering may differ.
Polyurethane injection into the void — the same chemistry we use for wet crack injection.
We trace the water to its entry point. A point source with dry wall above it is a tie hole; a line is a crack; a wet wall–floor seam is something injection cannot fix. If it is not a tie hole we say so.
Any failed mortar plug or old patching compound comes out. Resin will not bond through it, and leaving it in place is the most common reason a second repair fails too.
A port is set and hydrophobic polyurethane is injected until the void takes no more. The resin reacts with the water already present, expands through the annulus around the tie remnant, and cures as a closed-cell seal wrapping the steel.
Port removed, face made good, and the repair carries our transferable lifetime warranty.
Epoxy is a structural adhesive. It is the right answer for a dry structural crack and the wrong one here, for two reasons. It wants a dry, stable substrate, and a leaking tie hole is neither. And ACI’s field guide to epoxy injection (RAP Bulletin 1) is explicit that cracks caused by corroding steel should not be repaired by epoxy injection, because the corrosion continues and new cracking follows. That guidance is written about reinforcing steel and cracks rather than form ties, so we will not overstate it — but the logic transfers exactly: the corroding steel is the reason the hole is leaking, and epoxy does not address it.
Hydrophobic polyurethane cures because water is present, then holds constant volume — it does not swell and shrink with wet and dry cycles, and it tolerates freeze–thaw. In a wet, irregular void with a steel remnant in it, that is the behaviour you want.
Straight about the evidence: there is no ACI or ICRI document that specifically endorses polyurethane injection for form-tie holes. We use it on engineering rationale and field results, not on a citation, and you should be sceptical of anyone who claims otherwise.
Per hole, with volume pricing — because they rarely come alone.
| Situation | Typical range | Notes |
|---|---|---|
| Single leaking tie hole | $150 – $350 | One visit, one port, an hour or two on site |
| Two to four holes | $120 – $175 each | Most common scenario — one wall, one row |
| Five or more | from $100 each | Usually one form lift that was poured wet |
| Tie holes plus a cracked wall | See crack injection pricing | Cracks are priced separately, per crack |
These are GTA market ranges, consistent with prices published openly by Oakville, Aurora and Vaughan contractors. Your written quote is fixed before work starts — we do not price these by the hour, and you should not accept an hourly quote for them either. Run the numbers yourself on our cost calculator.
More than people expect, and we would rather show the arithmetic than quote a number we cannot source. Manufacturer forming tables put ties on roughly a 300–600 mm vertical by 600 mm horizontal grid, depending on the system and how fast the wall was poured. Older job-built forms used heavier through-rods on a sparser pattern — often two rows, roughly at knee height and shoulder height.
| Forming pattern | Interior holes per linear foot of wall |
|---|---|
| Modern panel forming, tight grid | ~4 |
| Modern panel forming, 600 × 600 mm | ~2 |
| Older two-row through-rod pattern | ~1.3 |
On a typical 150–200 ft perimeter that is anywhere from a couple of hundred to several hundred interior tie holes. Almost none of them will ever leak. The ones that do are usually the ones below the water table on the wet side of the house, or in a lift that was poured in bad conditions. Nobody needs every hole injected, and anyone quoting you for all of them is not diagnosing.
Estimates derived from published manufacturer spacing tables. We could not find an authoritative figure for holes per house, so we have shown the method rather than inventing one.
Real, verifiable Google reviews of Concrete Crack Repair Pros. Nothing paraphrased, nothing borrowed from a sister company.
6 Google reviews · Concrete Crack Repair Pros
Verified on our Google Business Profile at 64 Millwick Dr, North York — read every review on Google.
“Highly recommend for polyurethane crack injections. They also mentioned epoxy crack repair for floor cracks that worked really well.”
Giles McMahon · Google review, August 2026
“Highly recommend this company. John came out and assessed my issues. Repaired my foundation by making sure the cracks do not leak anymore.”
Kiera · Google review, August 2026
“I got the crack injection service. My basement foundation was leaking and these injections sealed things up.”
Trina · Google review, August 2026
“Great service. They came out and fixed the cracks in my foundation right away. Thank you”
Randy · Google review, August 2026
“Great job filling the cracks in my concrete foundation”
Rapp · Google review, August 2026
“Highly recommend this Team for foundation crack repairs. I hope to not need these guys again, but if I do, I won’t call any one else.”
Joel Williams · Google review, July 2026
The same resin and the same principle, applied along a crack instead of into a void.
When a structural bond is the right answer — and when it is not.
Horizontal, vertical, diagonal, stair-step: what each pattern means.
Including the one that matters here — injecting over an old patch.
Per-crack pricing and a calculator that gives you a range in 30 seconds.
The full service, across Toronto and the GTA.
Every technical claim above traces to one of these.
Send us a photo and we will tell you whether it is a tie hole, a crack, or something injection will not fix. Free written assessment, fixed price before any work starts.
