Homeowner Guide

Are Stair-Step Cracks Serious?

Stair-step cracks follow the mortar joints of brick or block construction in a zig-zag, staircase-like pattern rather than cutting straight through the material. They're one of the more recognizable foundation warning signs Missouri homeowners ask us about, but the presence of a stair-step crack alone doesn't tell the whole story.

What Determines the Severity

A handful of specific details matter far more than whether the crack exists at all:

• Width — hairline cracks under roughly 1/8 inch are common as masonry cures and settles slightly, and are usually not urgent on their own
• Whether it's still moving — a crack that measures the same today as it did a year ago is a different situation from one that's visibly widening
• Location — cracks near corners, above window or garage door openings, or appearing on more than one side of the house carry more weight than a single isolated crack
• Whether it's uniform or tapers — a crack that's narrower at one end than the other usually points to differential settling, meaning one section of the foundation is moving more than the rest

What We Actually Check

When we assess a stair-step crack, we measure width at several points, check whether similar cracking is showing up elsewhere on the house, and look for other symptoms alongside it — sticking doors, sloping floors, gaps opening along window trim. A single narrow crack with nothing else going on is often not urgent. Multiple cracks, a widening crack, or a crack paired with other symptoms is worth a real assessment rather than a guess based on a photo or description.