Cracks in Your Masonry: 
Which Ones Should You Worry About?

It’s one of the most common questions building owners and facility managers ask:
“Is this crack something to worry about?”

The truth is, cracks in masonry and concrete are normal to some extent. Buildings move. Materials expand and contract. Over time, small imperfections show up. But while some cracks are harmless, others can be early warning signs of structural issues or water intrusion.

Understanding the difference is key to protecting your building and your budget.

Why Cracks Happen in the First Place

Before diving into specific types of cracks, it’s important to understand why they occur at all.

Buildings are constantly under stress from:

  • Temperature changes (expansion and contraction)
  • Settling of the foundation
  • Moisture infiltration
  • Structural loads and shifting
  • Material shrinkage over time

Because of this, cracks are not unusual. The goal isn’t to eliminate all cracks—it’s to identify which ones matter.

Common Types of Cracks (and What They Might Mean)

Hairline Cracks in Concrete

These are thin, shallow cracks that often appear in concrete surfaces like walls, slabs, or foundations.

In many cases, these are caused by shrinkage as the concrete cures or minor temperature changes. They’re typically cosmetic and don’t indicate structural problems.

However, if these cracks begin to widen over time or allow water to seep through, they may need attention.

Stair-Step Cracks in Brick

These cracks follow the mortar joints in a step-like pattern, usually along one section of a wall.

This pattern often points to foundation movement or settling. While some minor settling is normal in buildings, larger or growing stair-step cracks may indicate uneven movement that should be evaluated.

If you notice this type of crack widening or spreading, it’s worth taking a closer look.

Vertical Cracks

Vertical cracks can appear in both masonry and concrete walls.

In many cases, these are related to normal building movement or thermal expansion and contraction. If they are narrow and consistent, they may not be a major concern.

However, wider vertical cracks, especially those that extend through multiple materials or levels, can suggest deeper movement issues.

Horizontal Cracks

Horizontal cracks are one of the more serious types to watch.

These often occur due to pressure or failure within the wall system, such as a corroding steel lintel or shelf angle expanding behind the masonry. As the steel rusts, it pushes outward, causing the masonry above to crack.

In other cases, horizontal cracks in concrete walls may indicate lateral pressure from soil or water, especially in below-grade conditions.

These cracks should not be ignored.

Diagonal Cracks

Diagonal cracks often run at an angle across walls or between openings like windows and doors.

These can be a sign of structural movement or uneven settling, particularly if they appear suddenly or grow over time.

When diagonal cracks are large or continue to change, they may require further evaluation to determine the underlying cause.

When a Crack Is a Red Flag

While not every crack is cause for concern, there are a few signs that should prompt closer attention:

  • The crack is getting wider over time
  • The crack allows water to enter the building
  • Multiple cracks are forming in the same area
  • The crack is accompanied by bulging, displacement, or loose materials
  • Doors or windows near the crack begin to stick or shift

If you notice any of these conditions, it’s best not to assume it’s cosmetic.

Why Patching Alone Isn’t Enough

One of the most common mistakes is simply sealing or patching a crack without addressing the underlying cause.

While patching may improve appearance temporarily, it doesn’t stop movement, water intrusion, or structural stress. In many cases, the crack will simply return, often worse than before.

Effective repairs start with understanding why the crack formed in the first place, and then applying the right solution to address both the cause and the symptom.

A Simple Way to Monitor Cracks

If you’re unsure whether a crack is active or stable, one of the best things you can do is monitor it over time.

A few simple steps:

  • Take clear photos of the crack
  • Mark the ends of the crack or measure its width
  • Re-check periodically (monthly or seasonally)
  • Note any changes in length or width

This helps determine whether the crack is static or continuing to move and provides valuable information if a professional evaluation is needed.

When to Call in an Expert

If a crack raises concern, especially if it involves movement, water intrusion, or structural elements, it’s worth bringing in a professional.

At Mid-Continental Restoration, we help building owners and facility managers assess masonry and concrete conditions, identify root causes, and recommend the right course of action. In some cases, that may involve a simple repair. In others, it may require coordination with an engineer.

The key is getting clarity early before a small issue turns into a major repair.

Don’t Ignore What Your Building Is Telling You

Cracks are one of the ways buildings communicate stress and change. Some are minor and expected. Others are early warning signs of bigger problems.

Knowing the difference and acting accordingly can save significant time, money, and risk down the road.

If you’re seeing cracks and aren’t sure what they mean, now is the right time to take a closer look.