The signs, in plain terms.

A horizontal crack running along the mortar line directly above the opening, following the top of the window, door or garage frame.

The crack often steps upward and outward at one or both ends of the opening, climbing through the mortar joints away from the corners.

The brickwork above the opening may look like it is sagging slightly, or sitting lower than the courses either side.

Rust coloured staining bleeding out of the mortar joint above the opening, sometimes running down the brick face below it.

In worse cases, the window or door frame binds when you open it, or the brick course directly above the opening has visibly lifted.

If several of these match what you are seeing, keep reading. If your crack runs diagonally through the wall and does not follow an opening, it is more likely a movement crack, and we cover that on a separate page below.

What is actually happening inside the wall.

A lintel is the horizontal support that carries the brickwork above every opening in a brick wall. You cannot see it from outside, but it is doing the structural work over every window, door and garage opening in the house. In most Sydney homes built before the mid 1990s, that lintel is a galvanised steel angle.

Galvanising is a protective zinc coating, and it does not last forever. When it fails, the steel underneath starts to rust. The important part is what rust does physically: it occupies significantly more volume than the steel it replaces. As the rust forms along the top face of the lintel, it pushes the brickwork sitting on it upward and outward. That is why the crack is horizontal, and why it sits right on the lintel line above the opening rather than wandering through the wall.

The pressure is slow and constant. It does not stop on its own, and it does not stabilise, because the steel keeps rusting for as long as it is exposed to air and moisture.

Sydney adds its own factor. Coastal and near-coastal suburbs see this problem far earlier and far more severely, because salt laden air accelerates the corrosion. Homes within a kilometre of the surf coast are the worst affected, and it is common to find every opening on the weather side of one of these houses in some stage of the same failure.

Water makes everything faster. If the cavity flashing above the lintel has failed, water reaching the steel accelerates the whole process, which is why the two problems often appear together. If you also have a damp patch on the inside of the wall, it is worth reading that page as well.

How to tell it apart from other cracking.

Not every crack near a window is a lintel problem, and the wrong repair wastes money. The pattern of the crack is the giveaway.

Lintel failure

Horizontal, sitting directly on the line above an opening. Often with rust staining in the joint, and sometimes a slight sag in the brickwork above. The crack belongs to the opening: it starts there, and it is worst there.

Settlement or footing movement

Usually diagonal or stepped through the brickwork. It runs through the wall rather than following an opening, and it is not associated with rust staining. This needs a structural engineer's assessment rather than a lintel replacement. We cover it on our stepped cracks page.

Thermal or shrinkage cracking

Fine, often vertical, typically at a corner or along a long uninterrupted run of wall. Generally stable over time, and generally not structural.

To be clear and honest about it: if the crack does not follow an opening, a lintel replacement is not the answer, and we will tell you that rather than quote it.

What happens if you do nothing.

This is not a scare story, just the mechanics of it. The corrosion continues, the crack widens, and more of the brickwork above the opening becomes displaced. What starts as a lintel replacement to one opening becomes a lintel replacement plus rebuilding the brickwork above it, which is a larger and more expensive job.

Once the joint above the lintel has opened up, water tracks freely through it into the wall cavity, and from there it can reach the internal leaf of the wall. At that point you are dealing with moisture damage inside the house as well as the structural repair outside.

In our experience it is rarely an emergency. Brickwork fails slowly, and a cracked lintel line does not mean the wall is about to come down. But it is never self correcting, and the repair does not get cheaper by waiting.

What a proper lintel replacement involves.

Needle propping. The brickwork above the opening is supported with props before anything is removed, so the load never rests on the window frame or the damaged lintel during the work.

Careful removal of the brick courses over the lintel. Bricks are taken out by hand and set aside for reuse wherever they are sound.

Cutting out the corroded lintel. The old steel is cut free and removed, and the bearing points either side of the opening are cleaned up.

Installing a new, correctly specified lintel. Galvanised steel or precast concrete suits most locations. For homes within roughly one kilometre of the surf coast, the correct specification is R4 duplex coated or grade 316 stainless steel, which meets the AS 2699.3 durability requirements for severe marine exposure. Fitting a standard galvanised lintel in that environment simply restarts the clock on the same failure.

New cavity flashing over the new lintel. This matters more than it sounds. Reinstating a lintel without new flashing above it recreates the exact failure mechanism, and the new lintel corrodes the same way the old one did. Remedial Brickworks includes new flashing over the lintel by default.

Rebuilding and repointing. The brickwork is rebuilt and the joints repointed in mortar matched to the existing wall, so the repair reads as part of the original wall.

Removing the propping and cleaning down. Props come out once the new work has taken its load, and the site is cleaned before we leave.

What affects the price.

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

The width of the opening. A garage opening carries far more brickwork than a bedroom window.

How many openings are affected. On coastal homes it is often more than one.

How much of the brickwork above has been displaced and needs rebuilding.

Whether the wall is single or double skin.

Access and working height. Ground floor openings are simpler than second storey work needing scaffolding.

The lintel specification the exposure requires, from galvanised steel through to grade 316 stainless.

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

Cracks above a window, door or garage opening.