Concrete Repair & Restoration in Ottawa & the National Capital Region - Crack Stitching & Slab Professionals

Why Concrete Repair Comes Before Every Coating

Any coating is only as reliable as the slab under it. Cracks that move, spalls left unpatched, and slabs that are out of plane are the leading reasons epoxy floors fail. Most contractors skip this work to keep the quote low.

We do not. The substrate repair the slab actually needs is line-itemed into every coating quote, so the floor we install lasts the full warranty. As Ottawa’s full-spectrum epoxy flooring contractor, prep is never an afterthought. Concrete repair is also offered as a stand-alone service for owners who want raw concrete restored without a coating 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 Freeze-Thaw Cycling and Concrete Damage

Few Ontario climates hit concrete as hard as Ottawa. Between 80 and 100 freeze-thaw cycles land here per winter, compared with 45 to 55 in the southern Ontario corridor. Water enters hairline cracks in autumn, freezes and expands through winter, and each cycle opens the crack a measurable amount. What was a 0.3 mm crack after one summer becomes a 1 mm-plus structural concern after five Ottawa winters.

Road salt makes it worse. Calcium chloride and sodium chloride tracked into garages and warehouses migrate 3 to 5 mm into the concrete, accelerating the freeze-thaw spalling cycle and leaving chloride contamination that undermines coating adhesion. Any Ottawa concrete repair has to account for that salt penetration during prep by grinding past the contaminated layer before any repair product or coating primer is applied.

Then Leda clay adds a third layer: seasonal heave. As the clay absorbs and releases moisture through freeze-thaw, its volume changes measurably, applying lateral and vertical stress on slabs that were poured over inadequate sub-base preparation. Homes built between the 1950s and 1970s in Centretown, The Glebe, and Old Ottawa South are especially affected, and their basement and garage slabs often show a signature pattern of multiple parallel cracks running perpendicular to the longest slab dimension.

Crack Repair: Stitching vs Fill-Only

Every cracked slab starts with classifying the crack. Dormant hairline cracks under 1 mm are opened slightly with a crack-chaser blade and filled with a rapid-set semi-rigid polyurea. Active cracks, ones with measurable seasonal movement, require mechanical stitching using carbon-fibre staples spaced 6 to 10 inches apart perpendicular to the crack axis, then a flexible polyurea fill on top. Staple layout follows ICRI Technical Guideline 310.3 for structural crack repair.

Skip the staples and lean on fill alone, and the crack re-opens on the next thermal cycle. We have redone other contractors’ polyurea-only work in Kanata and Barrhaven garages after a single winter because the fill split back open the moment the slab moved through its seasonal range.

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

Self-Levelling and Substrate Correction

Not every concrete problem is a crack. A meaningful share 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 any surface irregularity directly to the finished floor.

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

High spots are the opposite problem. A slab carrying prominent aggregate exposure, trowel ridges, or heaved zones from Leda clay movement is ground with a planetary grinder running diamond cup wheels. Grinding also improves adhesion by opening the pores of the concrete, moving 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 get their own treatment. Fill an expansion joint with rigid epoxy and the coating cracks directly over the joint line as the slab moves seasonally. The correct approach is to honour the joint: clean it out, insert a backer rod if it is deep, and fill with a flexible polyurea joint filler that stays pliable after cure. Expansion-joint repair on a two-car garage floor typically adds $150 to $350 CAD, a small line item that heads off a big cosmetic problem later.

Concrete Repair on Commercial and Industrial Floors

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

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

Scheduling is a real constraint on commercial jobs. Most Kanata and Nepean warehouse operators cannot pull a production floor offline for two or three days. Work runs in sections, isolating 20 to 30 percent of the floor at a time, repairing and priming each section overnight, and handing it back to service before the adjacent zone closes. Rapid-set polyurea crack fillers cure to full vehicle load capacity in 30 to 60 minutes, which lets us finish crack repair in one section and have forklifts back on it before the crew moves to the next bay. A written repair sequencing plan lands before work starts so the operations team can coordinate movement without guessing when each zone reopens.

Questions Property Owners Ask

Do my garage cracks need stitching, or just filling?

Cracks wider than 3 mm, cracks with visible vertical or horizontal displacement between the two faces, and any crack that has grown measurably over one or more winters should be stitched with carbon-fibre staples before any fill goes in. 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 the assessment and quotes fill-only on sight is a red flag.

What does concrete spall repair cost

Spall repair using a two-part epoxy mortar runs roughly $10 to $20 CAD per sq ft of affected area on residential work, driven by depth and access. A typical two-car garage with moderate spalling across 15 to 20 percent of the slab might cost $550 to $1,300 CAD for the repair alone, before any coating. Commercial floors with widespread industrial spalling are priced per sq ft on a project basis.

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

A two-car garage with moderate cracking and patching, followed by a full epoxy coating build, typically takes two days plus cure time. Day one is crack preparation and stitching, epoxy mortar patching, and diamond grinding. Day two is primer, broadcast basecoat, and topcoat. Light foot traffic is safe 12 to 24 hours after the final coat. Vehicle traffic is safe at 72 hours.

Does the concrete repair actually protect the coating warranty?

Yes, that is precisely why we do it. Coating manufacturers and professional installers void warranties on systems laid over substrates that were not properly prepared. When substrate repair is performed as part of a coating installation, that repair 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.