Almost every rendered or concrete façade in Sydney has cracks. Most are cosmetic, but even a fine crack lets water into the wall, and some cracks are a sign of movement or corroding steel that needs an engineer. This guide explains the common types, the warning signs and how cracks are usually repaired before a building is repainted.
Common types of façade cracks
- Hairline and craze cracking in render. A fine network of surface cracks, often from shrinkage as the render cured. Usually cosmetic, but it holds dirt and lets water reach the substrate.
- Cracks at the corners of windows and doors. Openings concentrate stress, so cracks often run diagonally from the corners. They can reopen if the wall keeps moving.
- Cracks along slab edges and lintels. Horizontal cracks at floor levels or above openings in brick buildings can come from slab movement or corroding steel. These need a closer look.
- Cracks with rust stains or spalling. Brown staining or concrete breaking away points to corroding reinforcement, often called concrete cancer.
- Cracks where different materials meet. Render over a junction between brick and concrete, or a wall with no movement joint, will often crack along that line.
- Cracks in parapets and cappings. Parapets take the most sun and weather, and water entering from the top can crack the render and leak into the floor below.
Why small cracks still matter
Water that gets into a crack can reach the steel in concrete, soak the substrate behind render and travel inside to ceilings and window heads. New paint over an unrepaired crack usually splits again along the same line within a season or two. Fixing cracks before painting is part of getting a repaint to last. Our article on why façade paint fails early covers this in more detail.
When to get an engineer involved
Ask an engineer to look at the building if you see:
- cracks that are wide, or getting wider over time
- stepped cracking through brickwork, or one side of a crack sitting proud of the other
- cracks with rust staining, or concrete breaking away
- doors or windows near the crack that have started to stick
- cracks that come back soon after they were repaired
A simple record helps: photograph the crack with a ruler or coin beside it and note the date, then repeat a few months later. That gives the engineer something to compare.
How façade cracks are usually repaired
The right repair depends on the cause, so the first step is an inspection. In general terms:
- Fine, stable cracks are opened slightly, cleaned and filled with a flexible filler, then covered by the coating system. Some systems include a crack-bridging membrane coat.
- Cracks that keep moving are treated like a joint: cut to a set width and sealed with a flexible sealant, or a proper movement joint is formed.
- Cracks caused by corroding steel need a concrete repair: the damaged concrete is removed, the steel is treated and the section is reinstated, following the engineer’s specification where one is needed.
- Cracked or drummy render that has lost its bond is cut back to sound material and patched.
On multi-storey buildings this work is often done by rope access, so every crack on an elevation can be reached from one set of anchors. See building remedial works and façade repairs for the full range of repairs we carry out.
Cracks and the next repaint
A repaint is the best time to deal with cracks, because the façade is already being accessed and prepared. Ask for crack repairs to be listed in the painting scope by type and location, with photos, so you can see what was done. Our strata painting page explains how a repaint is planned.
Frequently asked questions
Can I just paint over façade cracks?
Fine hairline cracks are often filled and covered by a suitable coating, but wider or moving cracks usually split new paint along the same line. They need to be repaired first, and some need an engineer to find the cause.
Who is responsible for cracks on a strata building’s façade?
External walls are usually common property, and in NSW the owners corporation must maintain and repair common property under section 106 of the Strata Schemes Management Act 2015. Check the strata plan and by-laws for your building.
Can façade cracks be repaired by rope access?
Yes. On multi-storey buildings rope access lets technicians reach cracks across a whole elevation from roof anchors, without full-height scaffolding. Larger structural repairs may need a different access method.
Source: Strata Schemes Management Act 2015 (NSW), section 106.
Seeing cracks on your building? Request a free quote or call 1300 926 176. We provide rope access services in Sydney, Wollongong and the Central Coast.
