BrickByBit

28 March 2026

Lintels explained: how openings in brickwork are spanned

Every window and door in a brick wall has a problem to solve: something has to hold up the bricks above the opening. That something is a lintel, and while you rarely see it, it is doing a lot of work.

What a lintel is

A lintel is a beam that spans the top of an opening and carries the weight of the brickwork (and sometimes the roof load) above it down to the brick on either side. Without it the bricks over a window would have nothing to sit on and would sag or collapse into the gap. Common types include:

  • Galvanised or stainless steel angle, very common behind the brick over windows and doors.
  • Concrete lintels, precast or poured.
  • Brick arches, where the bricks themselves are arranged to span the opening.

Why the right lintel matters

A lintel has to be sized for the span and the load above it, and it has to bear far enough onto the brickwork at each end. Get that wrong and the wall tells you over time. The bearing at each end is just as important as the beam itself, because that is where the load is handed back to the wall.

Signs a lintel is failing

Most lintel trouble comes from steel rusting. Older steel lintels can corrode, and as the steel rusts it swells and lifts the brickwork above it. This is common in older Melbourne homes where the original steel was not well protected. Watch for:

  • Cracking in the brickwork directly above a window or door.
  • A row of brickwork lifting or stepping just above an opening.
  • Rust staining bleeding down the brick or the mortar joint.
  • Mortar joints opening up above the opening.
  • Render cracking in a line over a window in a rendered wall.

Why you do not ignore it

A failing lintel does not get better on its own. The rust keeps growing, the brickwork keeps lifting, and what starts as a hairline crack can turn into loose, unsafe brickwork above an opening people walk under. Caught early it is often a manageable repair. Left for years it can mean taking down and rebuilding a section of wall.

Replacing a lintel

Replacing a lintel means carefully supporting the brickwork above, removing the old beam, fitting a properly sized and protected new one with the right bearing, and making good the brick around it. It is skilled work and not a job to improvise, because the wall above has to stay supported the whole time.

If you have cracking or rust staining above a window or door, send us a photo of the opening and your suburb and we will tell you whether the lintel is the likely cause and what it would take to put right.