Structural Crack Repair & Epoxy Injection · Kitchener

Foundation Crack Repair in Kitchener: Cracks That Are Moving

Most foundation cracks are not structural. The ones that are do not stop on their own. The first job is telling the two apart, and that takes a tape measure and a little patience, not a sales pitch.

Every poured concrete foundation in Kitchener has cracks. Concrete shrinks as it cures, and a vertical hairline crack in a wall poured in the 1990s in Doon South or the 2010s in Huron Park is almost always that: shrinkage, finished moving in the first year, going nowhere. If it lets water in during a March melt, it is a leak, and a waterproofing contractor seals it. That is not what this page is about.

This page is about the cracks that mean the foundation is still moving. Those need a structural repair, and sometimes they need something more than a repair to the crack itself, because the crack is a symptom.

How to tell a structural crack from a shrinkage crack

• It is getting wider. Mark the ends of the crack with a pencil and date. Measure the width at a fixed point with a feeler gauge or a crack card. Check it again after a season. A crack that grows is structural.
• It is wider at one end. A crack that tapers — wide at the top, tight at the bottom, or the reverse — means one side of the wall is rotating or dropping relative to the other.
• The two sides are not flush. Run a finger across it. If one side sits proud of the other, the wall has displaced, not just cracked.
• It runs diagonally from a window or the corner of the house. Diagonal cracks at 45 degrees from basement window corners are the signature of settlement. They come with sticking doors and cracked drywall upstairs.
• It is horizontal in a block wall. A horizontal crack along a mortar joint a few courses below grade is a wall being pushed in by soil. It is never cosmetic.
• It is a stair-step through block. Cracks that follow the mortar joints up and across in steps mean the blocks are moving relative to each other, from settlement at one end or pressure on the wall.

A hairline, vertical, non-tapering crack in a poured wall that has not changed since the house was built is none of those. Leave it, or have it sealed if it leaks.

Epoxy injection

For a structural crack in a poured concrete wall, the repair is injecting a structural epoxy under pressure until the crack is filled from the inside face to the outside. Epoxy bonds to both faces of the concrete and is stronger than the concrete itself, so a properly injected crack becomes a monolithic wall again. The process is: clean the crack face, set injection ports along its length, seal the surface between them with an epoxy paste, then inject from the bottom port upward until epoxy shows at the next port, cap, and move up. The paste is ground off afterward if the wall is going to be finished.

Two things people should know. Epoxy is rigid. It is the right material when the goal is to restore strength across a crack that has stopped moving after its cause has been dealt with. It is the wrong material for a crack that is still actively moving, because it will crack again beside the repair. And epoxy will not go into a wet crack properly, so a crack that is running water on the day is dried first or the timing is changed.

Carbon fibre stitching

Where a crack has some ongoing stress across it — a diagonal crack near a window, a crack in a wall that has a slight bow — the injection is reinforced with carbon fibre staples or short straps bonded across the crack at intervals. They tie the two sides together so the wall cannot open along the same line again. The surface is ground flat, the carbon fibre is saturated in epoxy and pressed onto the concrete, and it cures to a layer only a few millimetres thick that can be painted or finished over.

Cracks in block walls

The concrete block foundations under the 1960s and 70s houses in Forest Heights, Stanley Park, Centreville and Country Hills crack differently. Block cannot be injected the way poured concrete can; the cores are hollow and the joints are mortar. A stair-step crack in block is repointed and stitched with carbon fibre across the joints, or if the block itself has broken, the damaged units are cut out and replaced. A horizontal crack in block is not a crack repair at all. It is a bowing wall, and the repair is bracing the wall, which is its own page.

When the crack is a symptom

Injecting a settlement crack without dealing with the settlement is money spent on the wrong problem. If the measurements show a corner of the house dropping — the crack widening at the top, floors upstairs sloping toward that corner, a gap opening under the baseboard — the footing has to be supported first, usually with piers. The crack gets repaired after the movement is stopped. The first visit is where that gets sorted out, and it is why nobody should quote a crack repair from a photo.

Kitchener specifics

The clay under most of Kitchener moves with the seasons. It swells wet and shrinks dry, so cracks here often open in late summer and close a little in spring. That is why a single measurement is not enough and why a crack monitor left in place across a season is sometimes the honest answer before committing to a method. Houses on the fill lots in the newer subdivisions off Fischer-Hallman and toward the Doon valley, and older houses on the low ground near Schneider Creek, are the ones where a diagonal crack most often turns out to be settlement rather than shrinkage.

What this page does not cover

A crack that leaks but is not moving is sealed with a flexible polyurethane injection by a waterproofing contractor, along with the grading, weeping tile and drainage questions that go with it. That is a different trade with different materials, and it is not offered here. If your crack is that kind, you will be told so at the first visit rather than sold a structural repair you do not need.

Frequently asked questions

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