A flashing is a strip of metal or membrane that sheds water away from a junction: over a window head, along a parapet capping, where a roof meets a wall or at the edge of a balcony. When a unit leaks after heavy rain, the sealant or the membrane usually gets the blame, but a failed flashing is a common cause. This guide covers where flashings are found on a multi-storey building, the signs that one is failing and how leaks are traced and repaired.
Where flashings are found on an apartment building
- Window and door heads, to throw water clear of the frame.
- Parapet cappings, covering the top of the wall at roof level.
- Roof-to-wall junctions, such as apron and counter flashings where a roof meets a lift overrun, plant room or higher wall.
- Balcony edges and door thresholds, where the floor finish meets the façade.
- Penetrations, where pipes, brackets or ducts pass through the wall or roof.
Signs that a flashing is failing
- Water marks or bubbling paint above or beside a window after rain.
- Damp or stained ceilings close to an external wall on the top floor.
- Rust streaks running down the façade below a metal capping.
- Flashings that look lifted, bent or loose from the street or a balcony.
- Leaks that only appear in wind-driven rain from one direction.
Leaks in wind-driven rain are common on exposed Sydney buildings. Our guide to building leaks in wind-driven rain explains why.
Why flashings fail
- Sealant at the laps and fixings has aged and cracked.
- Fixings have corroded or worked loose, so the flashing lifts in wind.
- The flashing falls back towards the wall instead of away from it.
- Stop-ends are missing, so water runs off the end and into the wall.
- Corrosion from salt air or from contact between different metals.
- Damage from later work, such as new air-conditioning brackets, antennas or cabling.
Find the leak before replacing anything
Water can travel a long way inside a wall, so the stain inside is not always below the entry point. A proper investigation looks at the façade up close, then tests one area at a time with water while someone checks inside, working upwards from the lowest likely point. Moisture readings and thermal images help confirm the path. The result should be a short report with photos that shows where water got in and what needs repairing. See what happens during façade water testing and our high-rise leak detection service.
How flashings are repaired
- Reseal and refix laps and fixings where the flashing itself is sound. This is often a short-term fix if the design is the problem.
- Replace sections that are corroded, damaged or too short.
- Install new flashings or cappings with the right falls, laps and stop-ends.
- Repair the surrounding work, such as sealant around windows and render or paint damaged by the leak.
On a multi-storey building most of this can be done by rope access from the roof, without scaffolding. Where the repair involves waterproofing on a Class 2 apartment building in NSW, the work may fall under the Design and Building Practitioners rules for remedial building work. The NSW Government explains when a regulated design is needed, and your strata manager or engineer can confirm it for your building.
Frequently asked questions
Can flashings be repaired without scaffolding?
On many multi-storey buildings, yes. Window head flashings, parapet cappings and roof junctions can usually be reached by rope access from roof anchors.
How do you know the leak is the flashing and not the window?
By testing one area at a time with water while someone checks inside. Testing the window frame, the sealant and the flashing separately shows which one lets water in.
Is resealing a flashing enough?
Sometimes. If the flashing is sound and only the sealant at the laps or fixings has failed, resealing can work. If the flashing is too short, falls the wrong way or has no stop-ends, it needs to be replaced.
Leak after heavy rain? Request a free quote or call 1300 926 176. We provide rope access services in Sydney, Wollongong and the Central Coast.
