About Cracks in Basement Walls
How Foundation Wall Cracks Develop
All houses settle. Because of variations in soil properties, not every point on a foundation settles uniformly, which may cause racking doorframes and cracking walls. Good construction prevents differential settlement and minimizes the overall settlement.
Cracks in poured concrete walls can be found in almost all residential foundations. Most often, they occur in corners, from corners of windows, pour lines, holes for service lines or rod ties.
Over time, even minor cracks can grow larger and cause big headaches, such as loss of structural integrity. Repair all cracks exposed to moisture as quickly as possible to avoid more extensive damage The various causes include:
- Improper Concrete Mix (high water content)
- Rapid Concrete Curing
- Improper Expansion Control Joints
- Premature Removal of Concrete Forms (2 days instead of 7)
- Compressible Soil
- Premature Backfilling
- Improper Compaction of Fill Soil
- Expansive Clay Soils
- Uneven Moisture Around the Foundation
- Plumbing Leaks
- Poor Drainage
- Hydrostatic Water Pressure
Types of Foundation Wall Cracks
HAIRLINE – Hairline cracks typically develop within the first month and most foundations cracks appear within the first year. In most cases, the common wall cracks pose no structural concerns of foundation failure. The biggest problem they cause is water leakage.
Most foundation cracks will run vertically or at an angle. It is often caused by shrinkage of the concrete as it cures. Settlement cracks are also nearly always vertical. Such non-structural foundation cracks can be easily repaired by low-pressure injection.
HORIZONTAL – Clay soils in some areas are highly expansive. As the soil gets repeatedly wet and dry, it expands and shrinks, exerting lateral pressure on the foundation walls. If you have horizontal cracks along the midpoint of the wall, the wall is subjected to lateral pressure, which could bow and structurally damage the wall.
Cracks more than 1/4-inch wide, horizontal cracks in walls, cracks with misaligned edges or continuing movement may require professional assessment. You can monitor the crack’s length and movement by marking off the ends of the crack and making several “alignment marks" across the crack at various points. Foundation repair contractors can fix failed foundations by:
- Slab Jacking – Involves pumping a cement grout through small holes in the concrete slab
- Piering – Involves strategically placed mechanical jacks for lifting the settled beam to grade
Low-Pressure Injection for both the Pros and Homeowners
Polyurethane Injection – Crack injection works by filling the full length and depth of the crack with expandable polyurethane foam or epoxy. It forms permanent waterproofing seal so the process never needs to be repeated. Unlike surface repairs, the injected polymer is not vulnerable to weathering, ultraviolet rays, or traffic.
Filling the full depth of the crack rather than just bridging it on the surface prevents further deterioration of the concrete by groundwater. In addition, the injected polymer coats reinforcing steel and starves the corrosion process.
But most importantly, crack injection prevents future expensive problems. The potential damages done by water leaks to the finished basement or the cost of repairing concrete spalls caused by corrosion of reinforcing steel make clear the advantages of permanent crack repair.
Epoxy Injection is appropriate when structural strength of the repair is needed.
Repairing Cracks in Concrete Blocks Walls
While crack injection is best used for sealing cracks in poured concrete wall, it is not suitable for hollow concrete blocks. The reason is that the foam or epoxy would leak and wastefully expand in the hollow cores of the blocks. The proper repair would be routing out the crack with a hand-held grinder and then fill it with our ElastiPoxy Joint & Crack Filler Kit mixed with sand.
Need to Repair a Floor Crack? Use CrackWeld® Floor Repair Kit.