Water is coming through a crack in my basement wall. Is it structural?

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Orientation is the fastest read, and it decides which trade you need first. Vertical or near-vertical cracks in a poured concrete wall are usually shrinkage cracks that formed as the concrete cured. They are common, they frequently weep water, and they are typically repaired by injecting polyurethane or epoxy from the interior, which fills the crack through its full depth and seals it. Diagonal cracks radiating from a window or door corner are usually stress at a natural weak point and are often in the same category. Horizontal cracks are different. A horizontal crack running along a mortar joint in a block wall, particularly in the middle third of the wall height, indicates lateral soil pressure pushing the wall inward. That is a structural condition, not a leak, and sealing it treats the symptom of a wall that is being loaded beyond what it can carry. Any visible bowing, a wall that is out of plumb, or stair-step cracking at the corners belongs in the same category. The order matters. Waterproofing a wall that is failing structurally means paying twice, because the structural repair will disturb whatever was installed. Get a structural evaluation first, then water management. Width is the second read. Hairline cracks under about a sixteenth of an inch that are not moving are generally cosmetic even when they weep. Cracks wider than a quarter inch, cracks with offset between the two faces, and cracks that have visibly grown warrant evaluation regardless of orientation. Monitoring is easy and worth doing: mark each end of the crack with a dated pencil line and measure the width, then check again in three months. A crack that has not moved is a very different problem than one that has. Greater Cincinnati sits on glacial till over Ordovician limestone and shale, with clay-rich soils that hold water and hillside slopes that concentrate it.