Stair-Step Cracks in Brick: Foundation or Mortar?

Quick Answer

Stair-step cracks in brick follow the mortar joints in a zigzag pattern and are the classic exterior sign of differential foundation settlement. However, stair-step cracks in brick veneer (a decorative facing that carries no structural load) are often cosmetic — the critical distinction is whether the bricks themselves have displaced out of plane.

Quick Facts

Stair-Step Cracks in Brick Exterior Wall — Serious or Just Mortar?

You are walking along the outside of your house and you see a crack climbing the brick wall in a jagged staircase pattern — one step horizontal along a mortar bed joint, then one step vertical along a head joint, repeating upward. The crack may start near a window corner or at the base of the wall and zigzag toward the roofline. The mortar in the cracked joints is crumbling or missing entirely, and you can push a fingertip into the gap.

Run your hand across the bricks on either side of the crack. In a cosmetic mortar crack, both sides feel flush — the brick faces are in the same plane. In a structural crack, one side has shifted outward or inward relative to the other. This displacement is the difference between a $300 mortar repair and a $15,000 foundation project. Even 1/8 inch of displacement that you can feel with your fingertips matters more than a 1/4-inch-wide crack where both sides remain flush.

Check how far the crack extends. A stair-step crack that spans only 2–3 brick courses near a window may be localized stress from the lintel above. A crack that runs from the foundation up to the eaves — or one that continues around a corner — follows the path of differential movement through the entire wall section. Count the courses it crosses and measure the width at the widest point. Note whether the crack is wider at the top (settlement below) or wider at the bottom (heave below). On homes built with expansive clay soils (50% of US homes sit on expansive soils, per ASCE), these cracks frequently appear during or after drought cycles when the soil shrinks 10–30%.

Why This Happens

Step 1 — The foundation settles unevenly, and the rigid brick wall above must follow. Unlike wood-framed walls that can flex slightly, brick masonry is brittle. When one section of foundation drops even 1/4 inch relative to an adjacent section, the brick wall above cannot bend — it must crack.

Step 2 — The crack follows the mortar joints because mortar is weaker than brick. Mortar compressive strength is typically 750–2,500 PSI, while brick compressive strength exceeds 3,000 PSI. The fracture path takes the easiest route — stepping along the weaker mortar joints in the characteristic staircase pattern. Cracks wider than 1/2 inch indicate a 35% structural integrity failure risk (ACI 224R-01).

Step 3 — Continued movement displaces bricks out of their original plane. As differential settlement increases beyond 1/4 inch, the shear force pushes bricks on the settling side outward or downward relative to the stable side. This displacement — not the crack width — is the most reliable indicator of structural significance. A flush crack is a broken mortar joint; a displaced crack is a broken wall.

What To Do Next

1. Inspect the crack closely for free. Run your hand across both sides of the crack to check for displacement. Measure the crack width at its widest point using a ruler. Photograph the full crack from a distance to show the pattern, then close up to show width and any brick displacement. Date all photos.

2. Check interior walls behind the cracked exterior for matching symptoms. Go inside and examine the drywall on the same wall. Diagonal cracks above doors or windows on the interior, corresponding to the exterior stair-step pattern, confirm the movement is going through the full wall assembly — not just affecting the surface brick.

3. Get a professional evaluation based on what you find. If bricks are flush and the crack is under 1/4 inch, a mason can repoint the mortar joints for $250–$800 (Angi, Dec 2025). If bricks are displaced or the crack exceeds 1/4 inch, hire a structural engineer ($300–$780, HomeAdvisor, April 2025) to determine if foundation piers are needed. Push piers run $1,000–$3,000 each (Angi/HomeAdvisor, 2025), with typical projects requiring 5–10 piers.

When You Don't Need Repair

Stair-step cracks in brick veneer (decorative facing, not structural brick) that are under 1/4 inch wide, with no brick displacement, and no corresponding interior cracks are cosmetic mortar failures. Save your money. Brick veneer is attached to the wood-framed wall behind it with metal ties — it carries no structural load and does not support the roof or floors. Mortar shrinkage, thermal expansion, and minor settling commonly produce hairline stair-step cracks in veneer within the first 5–10 years of construction. These cracks can be repointed for appearance whenever you choose, but they do not require urgent attention or foundation repair. If the crack has not grown in 12 months of monitoring, it is stable.

Related Issues to Check

• Gaps between the brick veneer and window or door frames. When foundation settlement displaces the brick wall, the rigid window and door frames stay anchored to the wood framing behind the veneer. This creates a widening gap between the brick and the frame — a gap that allows water intrusion and accelerates mortar deterioration.

• Efflorescence (white mineral deposits) along the mortar joints near the crack. White powdery residue along the cracked mortar joints means water is migrating through the wall from behind. The stair-step crack has opened a path for moisture, and the dissolved minerals deposited on the surface confirm active water movement through the masonry.

• Chimney separation from the main structure. Chimneys built on independent footings sometimes settle at a different rate than the house foundation. A gap between the chimney brick and the house wall, combined with stair-step cracking in the chimney itself, indicates the chimney footing is moving independently.

Frequently Asked Questions

Is all stair-step cracking in brick caused by foundation problems? No. Stair-step cracks can also result from thermal expansion, original mortar shrinkage, or corrosion of the metal lintels above windows. Foundation-caused stair-step cracks are distinguished by brick displacement, matching interior symptoms, and crack widths that increase over time. A short crack near a window lintel with no displacement is likely lintel-related, not foundation-related.

What is tuckpointing? Tuckpointing is the process of removing damaged mortar from brick joints and replacing it with fresh mortar. A mason grinds out the old mortar to a depth of about 3/4 inch, then packs new mortar into the joint. This is appropriate for cosmetic stair-step cracks where bricks are flush and the foundation is stable. It does not address ongoing movement.

Can stair-step brick cracks cause water damage? Yes. Open mortar joints allow rain to penetrate into the wall cavity behind the brick. In homes with brick veneer over wood sheathing, this moisture reaches the sheathing and framing, causing rot and mold. Mold can establish within 24–48 hours of sustained moisture. Repointing cracked joints restores the water barrier.

How can I tell if my bricks are displaced? Place a straightedge (a 4-foot level works well) across the crack, spanning bricks on both sides. If the straightedge rocks or shows a gap on one side, the bricks are displaced. You can also run your hand across the crack — any step or lip between adjacent bricks is displacement. Displacement as small as 1/8 inch is significant.

Last reviewed: March 2026 · Sources verified against current industry data

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