How to repair hairline cracks in poured concrete foundations
1. Diagnostics: Is It Truly a Hairline Crack?
Before you reach for the repair kit, you must categorize the crack.
- Hairline Cracks: Usually vertical or diagonal, following a straight or slightly jagged path. These are perfect for DIY repair.
- Structural Cracks: If a crack is wider than 1/4 inch, runs horizontally across the wall, or if one side of the crack is pushing inward further than the other (offset), you should consult a structural engineer. These often indicate soil pressure issues that an injection kit cannot fix.
2. Choosing Your Material: Epoxy vs. Polyurethane
When repairing foundation cracks, you have two primary chemical options. Choosing the right one depends on the “status” of the crack.
Epoxy Injection
- Best for: Structural reinforcement.
- How it works: Epoxy is incredibly strong—stronger than the concrete itself once cured. It bonds the two sides of the crack together.
- Downside: It cures slowly and must be
