Roofing Defects

Flashing Failures

Roof flashings are the transition details that seal junctions between roof surfaces, penetrations and adjacent walls or structures. They are consistently among the most common sources of roof leaks — a correctly installed primary roof covering can remain watertight while a failed flashing allows concentrated water flow directly into the structure. Flashing failure includes corrosion, displacement, failed sealant, inadequate lapping and the use of incompatible materials that react and deteriorate over time.

Common Signs

Water ingress at specific locations corresponding to wall abutments, chimneys or penetrations
Rust staining on the facade below flashing locations
Visible separation, lifting or displacement of flashing from the substrate
Failed or absent sealant at flashing laps and junctions
Corroded or holed metal flashing in older buildings
Daylight visible at abutment junctions when viewed from the roof space
Staining and moisture at the internal face of walls adjacent to roof abutments

Common Causes

Corrosion of steel flashings in coastal or humid environments
Galvanic corrosion from incompatible metals in contact
Failed sealant at flashing laps and wall junctions from age and UV
Flashing displaced by thermal movement, wind or tile movement
Inadequate lapping of flashing sections — minimum 75 mm required
Step flashings not correctly integrated with the roof tile courses
Lead flashings cracking from work hardening and thermal cycling

Risk of Neglect

Water ingress causing damage to internal ceilings, walls and timber framing
Structural timber rot at wall plates and rafters from prolonged moisture
Mould growth in wall cavities at junction locations
Corrosion of embedded structural elements near flashing failures
Significant remediation cost if timber framing is affected
Internal staining and finish damage from repeated ingress events
Difficulty in isolating the specific ingress point without experienced investigation

Inspection Requirements

Inspect all ridge and hip flashing details for correct installation, lapping and sealant condition.
Inspect step flashings at wall abutments for correct integration with tile courses and wall cladding.
Check all penetration flashings including skylights, pipes and exhaust fans for correct upstand height and sealant condition.
Assess the material condition of all metal flashings for corrosion, holes and galvanic attack.
Inspect the lapping of all flashing sections — minimum 75 mm lap required.
Check that flashings are correctly counter-flashed or tucked into mortar joints at wall abutments.
Conduct a hose test at suspected flashing locations to isolate ingress points.
Record all defective flashings with photographs and measurements for the repair scope.

Start Inspection Checklist

Create a project inspection record, add defect locations, upload photos, and save notes for scope writing.

Typical Repair Methodology

01.Conduct a hose test to confirm all defective flashing locations before committing to the repair scope.
02.Remove all corroded, holed or displaced flashings from the affected locations.
03.For step flashings at wall abutments — remove tiles in the affected zone, strip out the existing flashing and install a new continuous Colorbond or aluminium step flashing correctly integrated with each tile course.
04.Counter-flash all step flashings into the mortar joint of the adjacent wall at minimum 75 mm depth and seal with polyurethane.
05.For penetration flashings — remove the existing flashing, inspect the substrate and install a pre-formed or site-formed flashing collar with a minimum 150 mm upstand.
06.Seal all flashing laps, joints and terminations with a compatible polyurethane sealant.
07.Re-bed and point all disturbed ridge and hip capping after flashing works.
08.Conduct a post-repair hose test to confirm all locations are watertight.
09.Repair internal plaster and ceiling damage after confirming repairs are effective.

Related Repair Systems

Step and counter-flashing systems
Penetration flashing collar systems
Ridge and hip flashing replacement systems
Valley flashing systems
Polyurethane and silicone flashing sealant systems

Open Repair Systems →