---
title: "Concrete Crack Repair Structural Cosmetic | AVANORTH"
canonical_url: "https://avanorth.ca/blog/concrete-crack-repair-methods-structural-cosmetic"
last_updated: "2026-03-10T07:33:42.379Z"
locale: en
meta:
description: "Concrete crack repair guide: types of cracks, causes, when to worry, repair methods, epoxy injection procedure, and structural vs cosmetic repairs."
"og:description": "Concrete crack repair guide: types of cracks, causes, when to worry, repair methods, epoxy injection procedure, and structural vs cosmetic repairs."
"og:title": "Concrete Crack Repair Structural Cosmetic"
"twitter:description": "Concrete crack repair guide: types of cracks, causes, when to worry, repair methods, epoxy injection procedure, and structural vs cosmetic repairs."
"twitter:title": "Concrete Crack Repair Structural Cosmetic"
---
AVANORTH Home
**Construction Tips**·April 26, 2026· 4 min read
# **Concrete Crack Repair Methods: Structural and Cosmetic**
Cracks in concrete are inevitable, but not all cracks are equal. Understanding the difference between structural and non-structural cracks, their causes, and the appropriate repair methods is essential for maintaining building integrity.
**AVANORTH Team**
AVANORTH Construction
Concrete cracks. It is one of the fundamental truths of construction. The question is not whether concrete will crack, but where, when, and how much. Some cracks are purely cosmetic. Others indicate structural distress that, if left unrepaired, can compromise the integrity of the structure. Correct diagnosis of the crack type is the essential first step before selecting a repair method.
---
## Types of Cracks and Their Causes
| Crack Type | Appearance | Width | Cause | Structural? |
| --- | --- | --- | --- | --- |
| Plastic shrinkage | Random pattern on surface, appears within hours of pour | Hairline to 1 mm | Rapid moisture loss from surface before concrete sets | No |
| Drying shrinkage | Linear cracks at corners, re-entrant corners, or mid-span | 0.1-1.0 mm | Volume reduction as concrete cures and dries over weeks/months | Usually no |
| Settlement / subsidence | Follows the line of reinforcement or changes in section depth | 0.5-3 mm | Concrete settling around reinforcement after placement | Potentially |
| Thermal | Regular pattern, often in mass concrete or large pours | 0.5-5 mm | Temperature differential between interior and exterior of mass concrete | Potentially |
| Structural (flexural) | Vertical cracks at mid-span of beams/slabs, widening at bottom | 0.3-5+ mm | Exceeding the flexural capacity of the member | Yes |
| Structural (shear) | Diagonal cracks near supports of beams | 0.5-5+ mm | Exceeding the shear capacity of the member | Yes (critical) |
| Corrosion-induced | Cracks along reinforcement lines, rust staining | Variable, growing | Expanding rust from corroding reinforcement | Yes (progressive) |
| Alkali-silica reaction (ASR) | Map cracking (three-way pattern), gel exudation | Variable | Chemical reaction between alkali cement and reactive aggregate | Yes (progressive) |
---
## When to Worry
> **General Rule:** Cracks wider than 0.3 mm (the width of a credit card edge), cracks that are growing, cracks that follow reinforcement lines, diagonal cracks near supports, and any crack accompanied by spalling, delamination, or rust staining should be evaluated by a structural engineer before repair. Do not simply seal them and assume the problem is solved.
---
## Repair Methods
### Non-Structural Crack Repair
| Method | Crack Width | Application | Material |
| --- | --- | --- | --- |
| Surface sealing | Hairline (less than 0.1 mm) | Brush-applied sealer over crack | Epoxy or methacrylate sealer |
| Routing and sealing | 0.1-5 mm | Widen crack with router, fill with flexible sealant | Polyurethane or silicone sealant |
| Crack injection (flexible) | 0.1-5 mm, active (moving) | Inject flexible polyurethane foam or gel into the crack | Polyurethane resin (flexible) |
| Gravity fill | 0.1-2 mm, horizontal surfaces | Pour low-viscosity resin over the surface, capillary action fills crack | Low-viscosity epoxy or methacrylate |
### Structural Crack Repair
| Method | Application | Material | Result |
| --- | --- | --- | --- |
| Epoxy injection | Inject structural epoxy under pressure into the crack. Ports placed along the crack, sealed between ports. | Two-part structural epoxy (higher strength than concrete) | Restores monolithic structural integrity |
| Stitching | Drill holes across the crack, insert U-shaped steel staples or carbon fibre plates, fill with epoxy | Steel or CFRP staples + epoxy | Prevents further crack opening, redistributes stress |
| External reinforcement | Bond FRP (fibre-reinforced polymer) plates or sheets over the cracked area | Carbon or glass FRP + epoxy adhesive | Increases structural capacity, confines crack |
| Full-depth repair | Remove damaged concrete, expose and treat reinforcement, replace with new concrete or repair mortar | Concrete or polymer-modified repair mortar | Complete renewal of the damaged section |
---
## Epoxy Injection Procedure
1. **Surface preparation:** Clean the crack and surrounding surface. Remove loose material, dirt, grease, and laitance.
2. **Install injection ports:** Bond injection ports (T-ports or surface-mounted) every 150-300 mm along the crack. Closer spacing for narrow cracks, wider for larger cracks.
3. **Seal the surface:** Apply epoxy paste seal along the crack surface between ports to prevent leakage during injection.
4. **Inject epoxy:** Start from the lowest port (gravity works with you). Inject until epoxy flows from the next port. Cap the injected port and move to the next one. Continue until the entire crack is filled.
5. **Cure:** Allow the epoxy to cure per manufacturer's instructions (typically 24-72 hours for full strength).
6. **Remove ports and seal:** Remove injection ports and grind the surface smooth.
> **AVANORTH Quality:** We diagnose before we repair. Every concrete crack on our projects is photographed, measured, and monitored over time before a repair method is selected. For structural cracks, we engage the structural engineer to determine the cause and specify the repair. We use only certified applicators for epoxy injection and FRP reinforcement. Band-aid repairs that mask a structural problem are never acceptable.
#concrete-repair #crack-repair #structural
### **Share this article**
[Share on X (Twitter)](https://twitter.com/intent/tweet?text=Concrete%20Crack%20Repair%20Methods%3A%20Structural%20and%20Cosmetic&url=https%3A%2F%2Favanorth.ca%2Fblog%2Fconcrete-crack-repair-methods-structural-cosmetic) [Share on LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Favanorth.ca%2Fblog%2Fconcrete-crack-repair-methods-structural-cosmetic) [Share on Facebook](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Favanorth.ca%2Fblog%2Fconcrete-crack-repair-methods-structural-cosmetic) [Share on WhatsApp](https://wa.me/?text=Concrete%20Crack%20Repair%20Methods%3A%20Structural%20and%20Cosmetic%20https%3A%2F%2Favanorth.ca%2Fblog%2Fconcrete-crack-repair-methods-structural-cosmetic)
## **Related Articles**
- [**Construction Tips****Elevator Installation in Mid-Rise Buildings: A Practical Guide**
Elevator installation is a critical path item in mid-rise construction. Understanding elevator types, shaft requirements, lead times, and coordination with other trades prevents costly delays.4 min read](https://avanorth.ca/blog/elevator-installation-mid-rise-buildings-guide)
- [**Construction Tips****Underpinning Methods: Strengthening Existing Foundations**
Underpinning deepens or strengthens an existing foundation to support additional loads, increase basement depth, or remediate settlement problems. Understanding the methods helps owners choose the right approach.3 min read](https://avanorth.ca/blog/underpinning-methods-strengthening-existing-foundations)
- [**Construction Tips****Quality Control Inspection Checklist for Construction**
Quality control in construction prevents defects, reduces rework costs, and ensures the finished building meets design specifications. Systematic inspection at each construction phase catches problems when they are cheap to fix.4 min read](https://avanorth.ca/blog/quality-control-inspection-checklist-construction)
- [**Construction Tips****HVAC System Selection for Commercial Buildings**
Choosing the right HVAC system affects occupant comfort, energy costs, and building flexibility for decades. Understanding the options helps owners and designers make informed decisions for commercial projects.4 min read](https://avanorth.ca/blog/hvac-system-selection-commercial-buildings)
### **Have a project in mind?**
Let's discuss how AVANORTH can bring your construction project to life — on time and on budget.
[**Get in Touch**](https://avanorth.ca/contact)
[** Back to Blog**](https://avanorth.ca/blog)