Mortar fails before bricks do. On most Sydney homes, the bricks themselves will outlast everyone in the building, but the mortar joints holding them together typically need replacing every 60 to 100 years. The longer failed mortar is left, the more damage it causes: damp ingress, fretting bricks, corroded wall ties, lintel rust, and structural cracking all start with the same root cause.
The good news is that mortar failure is one of the easier remedial problems to spot from the ground. Here are five signs that your brickwork needs repointing, and what to do once you’ve spotted them.
1. Crumbling or sandy mortar
The fastest test takes about ten seconds. Take a screwdriver or a key and drag the tip across a mortar joint. If the mortar comes away as sand or fine powder, it has lost its binding strength and is no longer doing its job. Healthy mortar will resist the scratch, leaving only a faint scuff.
The same test on a section of joint behind a downpipe or in a sheltered spot is a useful comparison, if those joints feel firm but the exposed elevations crumble, weathering has overtaken the mortar.
2. Visible gaps and open joints
Once mortar has fallen out, the gap can’t shed water properly. Rain runs straight in, gathers behind the brick face, and tracks down through the wall, into the cavity, the inner leaf, and eventually the building behind. Look for missing chunks of mortar, hollows at the centre of joints, or light visible through the wall in extreme cases.
South and west-facing elevations weather fastest in Sydney. Walls below window sills and around chimneys are the next most exposed. These are the spots to inspect first.
3. Damp patches inside the building
Damp on internal walls almost always traces back to a failed external surface. Brown stains around skirtings, peeling paint on the chimney breast, or a musty smell in a cupboard backing on to an external wall are all signs that water is getting in, and failed mortar is the most common entry point.
Internal damp is the point at which most owners finally call someone, but it’s rarely the earliest sign. By the time you’re seeing it inside, the joint outside has probably been failing for several years.
4. White staining (efflorescence)
Efflorescence is the white crystalline deposit that forms on a brick face when soluble salts are carried out of the wall by water. It’s a clear signal that water is moving through the brickwork, and that movement is what triggers fretting bricks, salt attack, and ongoing brick face damage. Repointing closes the entry point so the wall can dry out.
You can clean efflorescence off with a stiff brush, but it’ll come back if the underlying water ingress isn’t addressed.
5. Loose or rocking bricks
The most serious sign. Once the surrounding mortar is gone, individual bricks have nothing holding them in place. Push gently on any suspect brick, if it moves, it’s structurally compromised. On chimneys, parapets, and the top courses of older walls, this can be a safety issue and warrants immediate attention.
What to do next
If you’ve seen one or two of these signs in a localised area, you’re probably looking at partial repointing, perhaps a single elevation or the bottom three or four courses. If you’re seeing them across multiple elevations, a full repoint is more cost-effective than a piecemeal repair.
Either way, the wrong mortar mix is just as damaging as no repair at all. Hard cement-rich mortars trap moisture in the brick instead of letting the joint breathe, and on heritage stock that can destroy the bricks themselves within a decade. A specialist will sample your existing mortar and match the binder, sand, and colour before any rake-out begins.
If you’d like a written diagnosis with photos and a quote, we offer a free site visit across all Sydney Metro, or you can send us photos through our Project Brief form and get a quote without a site visit.