The signs, in plain terms.

A crack following the mortar joints in a stepped, staircase pattern rather than running straight through the wall.

Often widest at one end and tapering to nothing at the other.

Common locations: the corners of the building, above or below window and door openings, along long uninterrupted runs of wall, and where an older section of the building meets an extension.

Sometimes matched by a crack in the same position on the internal wall of the same room.

In more advanced cases, doors or windows that stick, or gaps opening up at cornices and skirtings inside the house.

What makes a wall crack in a staircase pattern.

Stepped cracking is a movement crack. Something has pulled or pushed the brickwork apart, and the wall has failed along its weakest line, which is the mortar between the bricks. That is why the crack follows the joints in a staircase rather than breaking straight through the bricks themselves.

The most common cause in Sydney is footing movement driven by soil moisture change. Large parts of Sydney sit on reactive clay, which swells when it is wet and shrinks when it dries. When the ground under one part of the building moves more than the ground under another, the wall spanning between them cracks.

Several things commonly drive or worsen that moisture change: trees drawing moisture out of the soil near the footing, leaking or poorly directed stormwater and downpipes, drainage that discharges right next to the building, and a plumbing leak below ground that nobody has found yet.

A second common cause is differential settlement between an original building and a later extension. The two sections sit on separate footings, poured many years apart, and they move independently. The crack opens where they meet.

Finally, long unrelieved walls with no articulation joint can crack from ordinary thermal and shrinkage movement, because the wall has no built-in place to flex.

How it differs from other cracking.

Stepped or diagonal cracking

Follows the mortar joints in a staircase pattern and runs through the wall rather than following an opening. This is movement, and it is the subject of this page.

A horizontal crack above a window, door or garage opening

A crack sitting on the line directly above an opening is a corroding steel lintel, not footing movement, and it is a different repair. We cover it on our cracks above windows and doors page.

Fine vertical cracking at a corner or mid wall

If it is fine, stable over years, and not widening, it is usually thermal or shrinkage movement and often does not need structural repair at all.

Mortar joints crumbling with no crack line

That is failed pointing rather than movement, and it is repaired by repointing the wall, not by structural stitching.

When you need a structural engineer first.

Crack stitching is the right repair for a wall that has cracked and is now stable, or where the cause of the movement has been identified and addressed. It is not a substitute for a structural assessment where the movement is ongoing.

Get an engineer's assessment before any repair is quoted if any of these apply: the crack is wider than roughly 5mm, it has visibly widened over recent months, doors and windows are binding, floors feel out of level, or the crack runs through the footing or slab as well as the brickwork.

To be plain about where we sit: Remedial Brickworks does not provide engineering reports. Where one is needed, we will say so rather than quote a repair that treats the symptom, and the engineer's report is something you commission and supply. We would rather lose a job than stitch a wall that needed an engineer first.

The cause also needs addressing alongside the repair. That can mean redirecting stormwater, correcting drainage that discharges beside the footing, or dealing with a tree growing close to the building. Stitching a wall while the ground underneath keeps moving means the wall cracks again, either along the old line or next to it.

What crack stitching actually is.

Crack stitching reinforces the cracked wall from within its own mortar joints. Slots are cut into the horizontal bed joints across the line of the crack, at regular vertical spacing up the wall. A helical grade 316 stainless steel bar is then bedded into each slot in a cementitious grout.

The bars tie the brickwork on either side of the crack back into a single structural element. Just as importantly, they spread load away from the crack line, so stress is no longer concentrated at the one weak point that failed. The slots are then grouted flush and repointed in colour matched mortar, so the repair is largely invisible once complete.

Grade 316 stainless steel is used because anything less corrodes inside the wall, and a corroding repair recreates the problem it was installed to fix.

It is worth spelling out why simply filling or sealing the crack does not work. Filler has no tensile strength. It carries no load, so at the first movement the crack reopens, either through the filler or beside it. Filling a structural crack hides the problem rather than repairing it.

What the work involves, step by step.

Inspect and confirm. We look at the crack pattern, its width and taper, and the likely cause, and confirm stitching is the right repair before anything is cut.

Cut the slots. Slots are cut into the horizontal bed joints at the required vertical spacing across the line of the crack.

Clean and flush. Each slot is cleaned out and flushed so the grout bonds to sound mortar and brick.

Install the bars. Helical grade 316 stainless steel bars are bedded into the slots in a cementitious grout.

Grout flush and repoint. The slots are filled flush and repointed in colour matched mortar so the stitched joints read as part of the original wall.

Replace damaged bricks. Any individual bricks broken beyond repair along the crack line are cut out and replaced with matching units.

What affects the price.

Every job is priced individually, because these variables genuinely change the scope of work:

The length of the crack, which drives the number of stitching bars required.

Whether one or both faces of the wall need stitching.

Working height and access. Ground level work is simpler than stitching a gable end from scaffolding.

Whether damaged bricks along the crack line need cutting out and replacing.

Whether an engineer has specified a particular bar density or spacing that the repair must follow.

We quote a fixed price after inspecting the site, and the quote sets out exactly what is and is not included.

Think this is what you are looking at?

Send photos of the crack through the quote form, ideally with something in shot for scale, and we will tell you whether this looks like a stitching job or one that needs an engineer first. Free site inspection across Sydney Metro. Licensed contractor 498429C, fully insured.

Stepped or diagonal cracks running through brickwork.