What does a stair-step brick crack wider at the bottom mean?

Reviewed by Preston, Oklahoma foundation repair consultant · Updated 2026-10-14

In short: A stair-step crack in brick that is wider at the bottom than the top suggests the wall has been pushed apart from below. On Oklahoma's expansive clay, that often means part of the foundation has risen as the soil swelled, but a neighboring section settling can look similar, so the reading is confirmed with a floor elevation survey.

What does this crack look like?

The crack steps through the mortar joints in a staircase line, usually from a corner, window or door, and it opens widest near its lower end, closing to a hairline higher up. Stair-step cracking in brick veneer is a well-documented distress pattern on expansive soils ¹.

What does the taper tell you?

Movement cracks in brick taper, wide at one end and hairline at the other ³⁴. The wide end marks where the wall has separated most. When the bottom is wider, the base of the wall has spread apart, which fits the area under one side of the crack pushing up, or the area on the other side dropping. Neither source gives a single rule for taper direction, so the floor survey decides. For the opposite pattern see stair-step crack wider at top.

What are the common causes?

Edge lift from swelling clay

Heave is upward movement of a foundation caused by soil swelling. Expansive clay absorbs water and swells, and upward movements of 6 to 8 inches or more have been reported in central Texas clays ¹. Under a slab, the perimeter can rise when the soil swells and drop when it shrinks ¹. Because the corners of a uniformly loaded slab press down on the soil less than the middle, they tend to lift relative to the center ². Poor drainage and lawn watering that wet the soil unevenly are named contributors ¹². See perimeter wetting heave (edge lift) and water ponding near the foundation.

Heave after a tree is removed

Trees draw water out of clay. Soil where a tree was removed shortly before construction may be drier than its surroundings and subject to localized heave ⁵. Repair guidance notes that removing a tree can halt or partly reverse settlement but can also cause heave, especially for trees that predate construction, and that a waiting period may be recommended ⁶. See post-tree-removal heave.

Movement after a pier repair

Inadequately anchored piers can be lifted by swelling clay, and insufficient vertical reinforcement can let uplift pull a pier apart; even the full weight of the structure is usually not enough to resist expansive forces ¹. A crack that reopens after a repair is covered under pier uplift or movement after repair.

How is heave or settlement confirmed?

• Elevation survey. A relative floor elevation survey, drawn on a plan, is the engineering step beyond a visual first impression ⁶. See elevation surveys.
• Crack activity. A clean crack edge suggests recent movement; a dirty or previously filled crack may be inactive ⁴.
• Monitoring. Cyclical movement may take six months or more to measure with a crack monitor ⁴.

The distinction matters because the two are managed differently; see heave vs settlement.

Related

• Stair-Step Brick Crack Wider at Top
• Perimeter Wetting Heave (Edge Lift)
• Post-Tree-Removal Heave
• Heave vs Settlement
• Cracks That Open and Close Seasonally