Mason or Structural Engineer? How to Tell What Your Cracked Wall Actually Needs

There's a crack in your brick. You have two very different phone calls available, and picking the wrong one first costs you either money or time — occasionally both.

Here's the distinction that governs everything: a mason repairs masonry that is wearing out. A structural engineer diagnoses a building that is moving. Those two conditions can look remarkably similar from the sidewalk and need completely different responses.

Paul Lally's Masonry has been working Chicagoland brick since 1988, and telling those apart is genuinely the first thing we do on any crack call. Sometimes the honest answer is "this isn't ours yet — call an engineer." Here's how to make that call yourself.

The core distinction

Deterioration is the material reaching the end of its service life:

• Mortar joints crumbling, receding, going soft and sandy
• Brick faces spalling — flaking, powdering, popping off
• Parging cracking and sheeting away
• Stone eroding, delaminating, losing its drip edge

Through all of that, the wall is still straight, still plumb, still in plane. It's doing its structural job; the surface and the joints have simply worn out. That's a mason's work, and it's most of what we do.

Movement is the wall going somewhere it shouldn't:

• Bowing or bulging outward or inward
• Leaning out of plumb
• Displaced across a crack — one side sitting proud of the other
• Horizontal cracking running across a wall
• Sections dropping relative to each other

That's an engineer's question first. Not because masons can't rebuild a wall — we can — but because rebuilding a wall that's still moving produces a new wall that moves the same way. The cause has to be identified and corrected before the masonry is worth touching.

The tests you can run yourself

1. The displacement test — the single most useful one

Run a finger across the crack, perpendicular to it.

Is it flush? Both sides in the same plane, just separated? That's typically thermal movement, historic settlement, or a joint failure — masonry territory.

Is one side proud of the other? The wall has moved out of plane. That's displacement, and it's structural until proven otherwise.

2. The movement test

Width matters far less than whether it's changing. A hairline crack that's wider this year than last is more concerning than a wide crack that hasn't moved in twenty years.

How to document it properly:

• Photograph the crack with a ruler or tape measure alongside
• Pencil-mark each end and write the date on the wall
• Re-check after a full freeze-thaw season, and again after a wet spring
• Note whether debris is falling from the joint (suggests active movement)

Give it a season. Chicagoland walls move seasonally with temperature and soil moisture, so a single snapshot tells you very little.

3. The pattern test

Crack pattern	Usually means	Who first
Stair-step through joints, flush	Settlement (often historic), thermal, or a lintel	Mason — diagnose the cause
Stair-step, widening, displaced	Active differential settlement	Engineer
Horizontal, across a wall, with inward bowing	Lateral pressure — soil, water, frost	Engineer, promptly
Horizontal, tight to an opening, with rust staining	Rust jacking from a corroding lintel	Mason
Vertical, at a corner or long wall	Thermal movement or missing expansion joint	Mason
Crumbling joints, no cracking	Mortar at end of service life	Mason
Bowing or bulging wall	Movement, or failed veneer ties	Engineer (solid) / Mason can assess (veneer)

4. The rest-of-the-house test

Masonry rarely moves alone. Look inside for corroborating evidence:

• Doors and windows sticking or out of square
• Fresh drywall or plaster cracks, especially at door and window corners on the same wall
• Floors sloping or noticeably springy
• Gaps opening between trim and walls, or at the top of baseboards
• A chimney separating from the house

Exterior crack plus multiple interior symptoms in the same area points strongly toward movement. An exterior crack with a perfectly normal interior is much more likely to be masonry wear or a localized cause.

The conditions that fool people

Three situations in Chicagoland look structural and usually aren't.

Rust jacking

A horizontal crack running along the joint just above a window, door, or garage opening — often with step cracks radiating from the top corners and orange-brown rust streaks below.

This looks alarming and is entirely a masonry problem. The steel lintel carrying the brick is corroding, and rust occupies several times the volume of the steel it came from, so it expands and lifts the masonry above. Not a foundation issue. See failing lintels and cracked brick above windows.

Bowing brick veneer

A bulging wall sounds structural by definition — but on a brick veneer wall it usually means the metal ties anchoring the veneer to the framing behind it have corroded and failed. The veneer carries no building load; it's a heavy skin that's lost its anchorage.

That's still serious — a veneer wall that isn't held flat can come away — but it's a masonry repair, not a foundation one. Knowing whether you have veneer or solid masonry changes the entire diagnosis, which is why our guide to brick veneer vs. solid masonry is worth five minutes.

Old, dormant settlement

Enormous numbers of Chicago-area homes have stair-step cracks from settlement that finished decades ago. The building found its position, stopped moving, and the crack has simply been sitting there ever since — letting water in, which is a real problem, but not a structural emergency.

Flush, stable, unchanged over years, no interior symptoms: repoint it properly and move on. Our guide to step cracks in brick walls covers how to read them.

When to call an engineer without waiting

Some conditions shouldn't wait for a mason's opinion:

• A wall visibly bowing, bulging, or leaning
• Horizontal cracking paired with any inward movement
• Significant displacement — one side of a crack well proud of the other
• Rapid change — a crack noticeably worse over weeks rather than years
• Multiple interior symptoms — sticking doors, sloping floors, fresh plaster cracks
• A chimney pulling away from the house
• Anything above an entrance or walkway that could fall — that's an immediate safety call regardless of cause

Why we tell people to call an engineer

We get asked why a masonry contractor would send work away. The answer is practical rather than noble: a wall that's still moving will reopen whatever we build.

If we rebuild a bowing section without the cause being corrected, that section bows again. You've paid for masonry twice and still have the original problem. That's a bad outcome for you and a worse one for a company whose family name is on the job.

So the sequence that actually works is:

1. Engineer diagnoses the cause and specifies the remedy.
2. The cause gets corrected — drainage, footing, framing, ties, whatever the diagnosis calls for.
3. The masonry gets rebuilt or repointed to that specification.

We're glad to work to an engineer's drawings, and having the plan before the wall opens up usually saves money rather than adding to it.

What each professional actually does

A structural engineer evaluates whether the structure is performing safely, determines why movement is occurring, and designs the remedy — footing work, drainage, reinforcement, wall anchoring, framing. They produce a specification. They generally don't perform the repair.

A mason repairs and rebuilds masonry: repointing, brick replacement, rebuilding sections, lintels, chimneys, parapets, stone, foundations at grade. We can tell you a great deal about what is happening and often about why — but where the question is whether your building is structurally sound, that determination belongs to an engineer.

A general home inspector documents observable conditions and recommends specialist evaluation. Their report is a starting point, not a diagnosis.

Chicagoland's particular contributions

Our region generates masonry cracking with unusual enthusiasm:

Expansive clay soils. Much of Chicagoland sits on heavy clay that swells when wet and shrinks when dry. That seasonal cycle moves foundations, and it's why so much local settlement cracking is genuinely seasonal rather than progressive.

Freeze-thaw cycling. Repeated hard cycles, sometimes several a week, driving water into masonry and expanding it roughly nine percent each time. This produces deterioration, and frost heave near grade can produce movement.

Century-old housing stock. The bungalows, greystones, and two-flats were built before modern footing practice, on soft brick and lime mortar. Most have settled — long ago, and stably.

Ungalvanized steel lintels throughout the postwar suburbs, now corroding on schedule and producing cracks that look structural and aren't.

Trees and drainage. Mature trees drawing moisture from clay soil at one corner, or a downspout that's been discharging against the foundation for fifteen years, both produce very convincing differential settlement.

What to do this week

1. Photograph every crack with a ruler alongside. Date them.
2. Run the displacement test — flush or proud?
3. Walk the interior looking for sticking doors, sloping floors, fresh plaster cracks.
4. Check the water management — gutters, downspout discharge, grade. A remarkable share of "structural" cracking turns out to be a downspout that's been soaking one corner for years.
5. Look above every crack for a lintel, a sill, a failed joint.
6. Then make the call — engineer if there's displacement, bowing, or interior symptoms; mason otherwise. And ask the mason directly whether they see anything suggesting movement.

Related services

Where the answer is masonry: tuckpointing and repointing, brick repair, brick replacement, lintel repair and replacement, foundation masonry repair, parapet wall repair, limestone and sill repair, chimney repair and rebuilds, residential masonry restoration, or historic masonry restoration.

Worth reading alongside: bowing and bulging brick walls, step cracks in brick walls, and when masonry repair becomes urgent.

The bottom line

Flush crack, straight wall, crumbling mortar → mason. Displaced crack, bowing wall, sticking doors → engineer first.

Width is the least useful measurement people reach for. Displacement, change over time, and corroborating interior symptoms are what actually separate a wall that's wearing out from a building that's moving.

And if you're not sure, ask a mason to look and to tell you honestly which one you have. Any masonry contractor worth hiring will say "call an engineer" when that's the real answer — because rebuilding a moving wall is a job that comes back.

Paul Lally's Masonry Inc. is a family-owned, insured masonry contractor serving Chicago and the Chicagoland suburbs since 1988 — tuckpointing, brick repair and replacement, chimney repair and rebuilds, lintel replacement, masonry restoration, and waterproofing for residential and commercial properties. Built on Craftsmanship. Backed by Experience.

We'll walk your wall and tell you plainly whether you're looking at masonry wearing out or a building that's moving — and if it's the second, we'll say so before you spend anything with us. Our family name is on every job.

Free on-site estimates — call (708) 448-8866 or request an estimate online.