Foundation Crack Injection: The Science of Permanent Repair
Foundation crack injection is the gold standard for repairing poured concrete foundation cracks. Whether you call it cement crack repair or concrete crack repair, the science is the same: unlike surface sealers, hydraulic cement patches, or caulk, injection fills the entire crack from interior surface to exterior soil, creating a complete seal that lasts the lifetime of your home.
Most homeowners notice water in the basement after rain, white powder on basement walls (efflorescence), or a musty smell in the basement — all signs that a foundation crack is allowing water infiltration. Crack injection addresses the root cause, not just the symptom.
How Crack Injection Works
The Problem Foundation cracks aren’t surface issues — they extend through the entire wall thickness (typically 8-10 inches of concrete). Surface repairs only address what you can see, leaving the rest of the crack open to water seeping through from saturated soil. Basement floor cracks leaking water are often caused by the same hydrostatic pressure that drives water through wall cracks.
The Solution Crack injection fills the complete crack void using either polyurethane foam or epoxy resin. Under controlled pressure, specialized resin is forced through injection ports spaced every 8-10 inches, filling the crack completely from interior surface through to the exterior soil. The result is a solid, permanent repair that’s stronger than the original concrete.
Our Injection Process
Step 1: Crack Assessment We evaluate each crack to determine:
- Cause of cracking
- Whether it’s active (still moving) or dormant
- Structural vs. non-structural nature
- Appropriate injection material
Step 2: Diamond Saw Preparation We use a diamond saw blade to grind a precise groove along the crack—1/2 inch wide and 1/4 inch deep. All debris is cleared. This creates a clean channel for port placement and ensures the finished repair sits flush with the wall.
Step 3: Copper Port Installation We install copper injection ports spaced 8-10 inches apart along the entire crack length. Each port is sealed in place with hydraulic cement. Unlike the plastic ports many contractors use, copper ports are stronger, seal better, and don’t leave unsightly bumps on your wall.
Step 4: 100 PSI Injection Starting from the lowest port, we inject resin at 100 PSI—far more than the industry standard. This isn’t low-pressure surface filling. Our pressure forces material through the complete wall thickness—8 to 10 inches—from the interior surface through to the exterior soil and down to the footer level. As each port fills, we move to the next, ensuring complete saturation.
Step 5: Finishing Each port is crimped off after injection. A specialized surface patch is applied over the groove, leaving a clean, polished finish. No ports sticking out, no rough patches—just a clean repair backed by our lifetime guarantee.
Injection Material Options
Flexible Polyurethane Foam
- Expands up to 20x original volume to fill voids completely
- Remains flexible after curing — accommodates seasonal movement
- Reacts with water to accelerate cure (ideal for active leaks)
- Meets ASTM C-920 performance standards for joint sealants
- Best for: Waterproofing, active cracks, moving cracks
Structural Epoxy Resin
- Creates bond stronger than the original concrete
- Rigid when cured — restores full structural integrity
- Best for: Structural cracks, load-bearing walls, cracks requiring maximum strength
Hybrid Approach Some cracks benefit from both materials — structural epoxy resin for strength at critical points, flexible polyurethane foam for expansion and waterproofing throughout. We select the right material (or combination) based on 20+ years of diagnosing New England foundations.
Why Injection Beats Other Methods
| Method | Fills Complete Crack | Flexible | Structural | Permanent |
|---|---|---|---|---|
| Injection | Yes | Available | Available | Yes |
| Surface Seal | No | Varies | No | No |
| Hydraulic Cement | No | No | No | No |
| Caulk | No | Yes | No | No |
Types of Cracks We Inject
- Vertical shrinkage cracks — the most common type in poured concrete foundations
- Diagonal settlement cracks — often caused by soil settlement or frost heave
- Cracks around windows and doors — stress concentration points
- Floor-to-wall joint cracks (cove joints) — where the slab meets the footing
- Cracks at cold joints — where concrete pours met during original construction
What Crack Injection Costs
Most foundation crack injection repairs cost $800-$1,200 per crack, depending on length, accessibility, and material required. This is a fraction of the cost of exterior excavation ($3,000-$8,000+) and provides a superior seal. Every repair includes our lifetime guarantee.
When Injection Isn’t the Answer
We believe in honest assessment — we’ll tell you when injection isn’t the right fix. Some situations require different approaches:
- Severely deteriorated concrete: Crumbling or spalling concrete may need section replacement
- Bowing walls: Require stabilization (often with carbon fiber staples or steel reinforcement) before crack repair
- Active structural movement: Must address the cause first — soil pressure, drainage, or footing issues
- Block wall cores: May need interior drainage instead of injection
- Cracks wider than 1/2 inch with displacement: May indicate a structural issue requiring engineering assessment
We’ll always recommend the right solution — even if it means referring you to a structural engineer or another specialist. That honesty is how we’ve built our reputation over 20+ years. Text us a photo for a free assessment.
The Attack A Crack Injection Guarantee
- Lifetime warranty on all injection repairs
- 100 PSI injection pressure — far above industry standard
- Complete crack filling — we don’t stop until it’s done
- Clean, professional work — your basement stays clean
- 20+ years of New England foundation experience
