Failed cavity flashing is one of the most misdiagnosed problems in Sydney brickwork. Most people treat the symptom. We fix the cause.
What is cavity flashing?
A cavity wall is two separate skins of brickwork, an outer weather-exposed leaf and an inner structural leaf, with a 40–75mm gap between them. The cavity provides insulation and, more importantly, a drainage path for any water that gets through the outer leaf during rain.
Cavity flashing is a waterproof membrane built into the base of that cavity, and over every opening cut into it, windows, doors, vents, and pipe penetrations. Its job is to catch water that has tracked through the outer skin and redirect it back outside through small openings called weep holes, before it reaches the inner leaf or the building behind.
In Sydney’s older brick buildings, particularly stock built between 1960 and 1995, the original flashings were lead, bitumen-coated felt, or galvanised metal. All three deteriorate. They crack, corrode through, get punctured during plumbing or HVAC works, or get bridged by mortar droppings during the original construction. When that happens, the water that the flashing was supposed to redirect outside ends up trapped against the inner leaf.
Common in Sydney buildings built between 1960 and 1995, especially those within 5km of the coast where salt-laden air accelerates deterioration.
Signs your cavity flashing has failed
Not sure if it’s cavity flashing or something else?
Send us photos via our Project Brief form, we’ll give you a preliminary assessment within 24 hours. No site visit needed.
Send Photos for Assessment →Our replacement process
We inspect the wall internally and externally, identify the failure point, and confirm the flashing is the cause, not a roof leak, rising damp, or a separate plumbing issue. Misdiagnosis is the most expensive mistake in this category of work.
We carefully remove the affected course or courses of brickwork above the flashing line, supporting the wall as we go. Salvageable bricks are set aside for reinstatement.
The failed flashing material is fully removed, the cavity is cleaned out, and any mortar bridges or rubble that have built up across the cavity are cleared away.
Modern alkathene, EPDM, or stainless step flashing, selected for the location, is bedded into the cavity, correctly lapped, and dressed so water sheds outward, not in.
New weep holes are formed at correct centres, typically 600–1200mm, so the cavity drains properly going forward.
Removed bricks are relaid using mortar matched to the existing wall. Where bricks have been damaged during removal, we source matching units before reinstatement.
Surrounding mortar joints are repointed for visual continuity, and the work is cleaned down so the repair is invisible from across the street.
Why Sydney is particularly susceptible
Sydney’s coastal location means salt-laden air attacks original lead and metallic flashings from inside the cavity. Coastal homes and unit blocks experience flashing failure at significantly faster rates than equivalent buildings inland. The same flashing that lasts 60 years in Parramatta might last 30 in Coogee.
Beyond climate, the high concentration of 1960s–1980s brick strata buildings in Sydney’s inner suburbs means cavity flashing replacement is one of the most common remedial scopes in the city, particularly in the Eastern Suburbs, Inner West, and lower North Shore. We work on these buildings constantly and know the failure patterns by suburb and era.
For builders and strata managers
Cavity flashing failure is one of the most common defects identified in strata building condition reports and pre-purchase building inspections. We work directly with strata managers requiring a written scope of works, builders who encounter flashing failures during renovation work, and inspectors who need a reliable specialist to refer their clients to.
Areas we service
We carry out cavity flashing replacement across all Sydney Metro, with particular experience in:
Eastern Suburbs
Randwick · Coogee · Maroubra · Bronte · Bondi
Inner West
Leichhardt · Marrickville · Newtown · Annandale · Glebe
North Shore
Neutral Bay · Cremorne · Mosman · Kirribilli
CBD Surrounds
Surry Hills · Redfern · Erskineville · Waterloo
Northern Beaches
Manly · Dee Why · Narrabeen
Also serviced
Sutherland Shire · Western Suburbs · Hills District
FAQ
Ready to fix the problem?
Send photos via our Project Brief form and we’ll assess your cavity flashing issue without a site visit.
Further reading
Get a detailed quote within 24 hours. Photos accepted via our Project Brief form.