Concrete Repair & Restoration in Ottawa, ON - Crack Stitching & Slab Professionals

Why Concrete Repair Comes Before Every Coating

A coating is only as good as the slab under it. Cracks that move, spalls that haven’t been patched, and slabs that are out of plane are the most common reasons epoxy floors fail, and most contractors skip this step to keep the quote low.

We don’t. Every coating quote includes the substrate repair the slab actually needs, so the floor we install lasts the full warranty. As Ottawa’s full-spectrum epoxy flooring contractor, the prep is never an afterthought. Concrete repair is also a stand-alone service for owners who want raw concrete restored without a coating system on top, and it is the first step in most epoxy floor repair and recoat jobs.

What is Included

• Visual and tactile damage assessment
• Crack stitching with carbon fiber staples
• Rapid-set polyurea crack filling
• Epoxy mortar patches for spalls and corners
• Self-levelling underlayment for uneven slabs
• High-spot milling and expansion-joint detailing
• Final surface profile prep ready for coating
• Documented before/after for warranty

Ottawa’s Freeze-Thaw Cycle and Concrete Damage

Ottawa’s climate is one of the hardest on concrete in Ontario. The city averages 80-100 freeze-thaw cycles per winter, compared to 45-55 in the southern Ontario corridor. Water enters hairline cracks in autumn, freezes and expands through winter, and each cycle widens the crack by a measurable amount. A 0.3 mm crack after one summer becomes a 1 mm+ structural concern after five Ottawa winters.

Road salt compounds the problem. Calcium chloride and sodium chloride tracked into garages and warehouses penetrate the concrete surface to a depth of 3-5 mm, accelerating the freeze-thaw spalling cycle and leaving chloride contamination that interferes with coating adhesion. Concrete repair in Ottawa must account for this salt penetration during the preparation phase, grinding past the contaminated layer before any repair product or coating primer is applied.

The Leda clay beneath much of the city adds a third factor: seasonal heave. As the clay absorbs and releases moisture through the freeze-thaw cycle, the soil volume changes measurably, putting lateral and vertical stress on slabs that were poured without adequate sub-base preparation. Homes built in the 1950s through 1970s in Centretown, The Glebe, and Old Ottawa South are particularly affected, and their basement and garage slabs often show a pattern of multiple parallel cracks running perpendicular to the longest slab dimension.

Crack Repair: Stitching vs Fill-Only

The repair sequence for cracked slabs starts with classifying the crack. Dormant hairline cracks under 1 mm wide are ground open slightly with a crack chaser blade and filled with a rapid-set semi-rigid polyurea. Active cracks, ones that show measurable movement across seasons, require mechanical stitching with carbon fiber staples set 6 to 10 inches apart perpendicular to the crack axis, followed by a flexible polyurea fill. The staple pattern follows guidelines from the ICRI Technical Guideline 310.3 for structural crack repair.

Skipping the staples and relying on fill alone means the crack re-opens under the next thermal cycle. We have re-done other contractors’ polyurea-only repairs in Kanata and Barrhaven garages after a single winter because the fill cracked right back open once the slab moved through its seasonal range.

Spall repair follows a different process. Delaminated or hollow areas must be fully removed back to sound substrate before patching. Shallow spalls up to 25 mm deep are rebuilt with a two-part epoxy mortar compound at roughly 100 percent solids, which bonds directly to the surrounding concrete without a separate bonding agent. Deeper structural spalls, more common in post-war industrial buildings along the Queensway corridor, may require a cementitious polymer-modified repair mortar applied in lifts to avoid shrinkage cracking. Either way, the patched area must achieve a CSP 3 to CSP 5 profile before any primer or basecoat is applied.

Self-Levelling and Substrate Correction

Not every concrete problem is a crack. A significant portion of residential and light-commercial slabs, particularly poured-in-place basement floors from the 1950s through 1980s in areas like The Glebe and Sandy Hill, have out-of-plane surfaces from differential settlement, heave, or inconsistent original flatwork. A floor that varies by 10 mm or more across a 3-metre straightedge is not suitable for most broadcast flake or metallic epoxy systems, which telegraph surface irregularities directly to the finished surface.

The standard correction method is a cementitious self-levelling underlayment (SLU) poured to fill low spots and bring the slab within acceptable tolerances before coating. A quality SLU product flows to a feathered edge at 1-2 mm and can be built up to 50 mm in a single pour, depending on the formulation. The floor must be primed with a penetrating epoxy primer before the SLU is poured to ensure bond and prevent the slab from pulling moisture out of the underlayment too quickly.

High spots are the opposite problem. A slab with prominent aggregate exposure, trowel ridges, or heaved areas from Leda clay movement requires grinding with a planetary grinder equipped with diamond cup wheels. Surface grinding also improves adhesion by opening the pores of the concrete, transitioning the surface from a closed CSP 1 to an open CSP 2 or CSP 3 profile suitable for a 100-percent-solids epoxy primer.

Expansion joints require careful treatment. Filling expansion joints with a rigid epoxy material causes the coating to crack directly over the joint line as the slab moves seasonally. The correct approach is to honour the joint: clean it out, apply a backer rod if the joint is deep, and fill with a flexible polyurea joint filler that remains pliable after cure. Expansion joint repair on a two-car garage floor typically adds $150 to $350 CAD, a small line item that prevents a large cosmetic problem.

Concrete Repair on Commercial and Industrial Floors

Commercial concrete repair carries higher stakes than residential work in two ways: the floor is usually in active service and cannot be closed for a week, and the loads it carries after repair are far heavier than a residential vehicle. Loading bays’s industrial parks along Merivale Road and Hunt Club see forklifts at 8,000 to 12,000 kg gross vehicle weight, with hard polyurethane wheels that concentrate that load into a contact patch smaller than a boot heel. Any spall patch or crack fill that is not fully bonded to the surrounding substrate will shatter under that load within weeks.

For commercial slab repair, we use a two-part epoxy mortar system with a compressive strength above 70 MPa after cure, well above the 25-35 MPa compressive strength of standard ready-mix concrete. In food-processing facilities and commercial kitchens across where steam cleaning at high temperature is part of the daily routine, we specify a novolac epoxy mortar rated for continuous chemical exposure rather than a standard bisphenol-A epoxy.

Scheduling is a real constraint on commercial repair jobs. Most Kanata and Nepean warehouse operators cannot take a production floor offline for two or three days. We work in sections, isolating 20 to 30 percent of the floor at a time, repairing and priming each section overnight, and returning it to service before closing off the adjacent zone. Rapid-set polyurea crack fillers cure to full vehicle load capacity in 30 to 60 minutes, which allows us to complete crack repair in one section and have forklifts back on it before the crew moves to the next bay. We provide a repair sequencing plan in writing before work starts so the operations team can coordinate movement without guessing when each zone will be ready.

Questions Property Owners Ask

How do I know if my garage floor cracks need stitching or just filling?

Cracks wider than 3 mm, cracks with visible vertical or horizontal displacement between the two sides, and any crack that has grown measurably over one or more winters should be stitched with carbon fiber staples before filling. Hairline cracks under 1 mm in an otherwise stable slab can be filled with a semi-rigid polyurea without stitching. If you are unsure, a contractor who skips an assessment and quotes fill-only on sight should be a red flag.

What does concrete spall repair cost

Spall repair using a two-part epoxy mortar runs approximately $12 to $22 CAD per square foot of affected area for residential work, depending on depth and access. A typical two-car garage with moderate spalling across 15-20 percent of the slab might cost $600 to $1,400 CAD for the repair work alone, before any coating. Commercial floors with widespread industrial spalling are priced per square foot on a project basis.

How long does a full concrete repair and recoat take for a two-car garage?

A two-car garage with moderate cracking and patching needs, followed by a full epoxy coating system, typically takes two days plus cure time. Day one covers crack preparation and stitching, epoxy mortar patching, and diamond grinding. Day two covers primer, broadcast basecoat, and topcoat. The floor is ready for light foot traffic 12-24 hours after the final coat, and ready for vehicle traffic at 72 hours.

Does concrete repair before coating affect the warranty on the epoxy floor?

Yes, it protects it. Coating manufacturers and professional installers void warranties on systems applied over substrates that were not properly prepared. When we perform substrate repair as part of a coating installation, that repair work is documented in the project file and the coating warranty covers the entire installed system. Skipping substrate repair to save $300 on a $2,000 floor installation is how homeowners end up with a failed floor and no warranty claim to make.