Foundation Crack Types — Which Are Serious?
A Long Island homeowner's guide to the four main foundation crack types and what each one means structurally.
Not every crack is a structural emergency. But not every crack is cosmetic either. The difference between a $500 injection and a $20,000 pier job starts with identifying which type of crack you're looking at.
VERTICAL HAIRLINES: Usually cosmetic. Under 1/8 inch wide, running straight up-and-down, consistent in width top to bottom. Caused by normal settlement or minor concrete shrinkage. Monitor with a dated photo; injection only if seeping water.
HORIZONTAL CRACKS: Structural. Almost always indicate lateral pressure from saturated soil pushing the wall inward. Do NOT inject — the wall is moving and injection will fail. Calls for carbon fiber reinforcement or wall anchors.
STAIR-STEP CRACKS: Structural. Diagonal cracks following mortar joints in concrete block walls. Indicate settlement on one side of the wall or lateral pressure from one corner. Needs pier stabilization OR carbon fiber depending on cause.
DIAGONAL CRACKS: Usually settlement. From a corner of a window or door running down and out. Indicates one side of the foundation is moving downward relative to the other. Pier systems are the typical fix.
When in doubt, send us a photo. We'll tell you what type of crack you have, whether you need us, and what the repair would run.