Yes, you can spot many of the common warning signs of faulty roof flashing without needing a professional inspector — at least from a safe vantage point. While a licensed building inspector will always give you a more thorough assessment, knowing what to look for can help you catch problems early and avoid costly water damage to your home.
What Is Roof Flashing and Why Does It Matter?
Roof flashing is the thin metal (usually aluminium, zinc, or galvanised steel) or sometimes butyl rubber sheeting installed at joints and transitions on your roof — around chimneys, skylights, valleys, parapet walls, and where the roof meets vertical walls. Its job is to direct water away from these vulnerable junctions and into the gutters or off the roof surface.
When flashing fails, water can penetrate your roof structure, leading to rot, mould, damaged insulation, and even structural issues. Under the NZ Building Code, roofs must comply with Clause E2 (External Moisture), which requires buildings to be protected from water ingress. Faulty flashing is one of the most common causes of E2 failures.
Signs You Can Check From the Ground or Inside Your Home
You don't need to climb on the roof to spot many warning signs. Always prioritise your safety — never walk on a roof unless you are trained and have the right equipment.
Inside the House
- Water stains on ceilings or walls — Brown or yellowish rings, especially near chimneys, skylights, or exterior walls, are a classic sign of water getting in through failed flashing.
- Damp or musty smells in the ceiling space or upper rooms, which can indicate ongoing moisture intrusion.
- Peeling paint or bubbling plasterboard on interior walls or ceilings near roof junctions.
- Mould growth on ceiling surfaces, particularly in corners or around light fittings near the roofline.
- Daylight visible through the ceiling space — if you can safely access your roof cavity, look for any gaps where light comes through around flashings.
From the Ground (Using Binoculars)
A good pair of binoculars lets you inspect your roof from the ground safely:
- Lifted, bent, or missing flashing — Look for metal that has pulled away from walls, chimneys, or skylights.
- Rust or corrosion on metal flashing, which can indicate the material is breaking down and no longer watertight.
- Gaps or cracks where flashing meets masonry, tiles, or roofing iron.
- Failed sealant — Cracked, shrunk, or missing sealant beads along flashing edges are a common failure point.
- Debris build-up in roof valleys, which can cause water to back up behind flashing.
- Loose or displaced roofing material near flashing junctions.
Common Flashing Locations to Check
| Location | What to Look For |
|---|---|
| Chimney | Rust, gaps between flashing and masonry, lifted step flashing |
| Skylights | Cracked sealant, pooling water, lifted edges |
| Roof valleys | Debris, corrosion, gaps in valley iron |
| Parapet walls | Capping pulled away, water stains on interior walls below |
| Roof-to-wall junctions | Flashing lifted or missing, rust streaks on cladding |
After Heavy Rain: The Best Time to Check
One of the most reliable ways to spot flashing issues is to check your ceiling and roof space during or shortly after heavy rain. Active drips or wet patches that appear only during rain are a strong indicator of flashing failure rather than condensation. Note exactly where the water appears inside — this helps a tradesperson pinpoint the source.
What You Should NOT Do
- Do not walk on your roof unless you are a trained professional with appropriate safety equipment. Falls from roofs are a leading cause of serious injury in New Zealand — WorkSafe NZ has clear guidelines on working at height.
- Do not attempt to re-seal or re-fix flashing yourself without understanding the correct materials and methods, as a poor repair can make things worse.
- Do not ignore signs of water ingress — even small leaks can cause significant structural damage and mould issues over time, which is also relevant under the Healthy Homes Standards if you are a landlord.
Keeping Records
If you spot any of these warning signs, take dated photos from a safe position. This documentation is useful when talking to a tradesperson or building inspector, and can be important for insurance claims.
When to Call a Professional
If you notice any of the signs above, it's time to call in a qualified professional. A licensed building inspector or experienced roofing tradesperson can safely access the roof, identify the exact source of the problem, and advise on the correct repair. Roof flashing repairs are not restricted work under the Building Act, but they do need to comply with the NZ Building Code (Clause E2) and relevant standards. Depending on the extent of the work, a building consent may or may not be required — always check with your local council if you're unsure.
For significant repairs or full flashing replacement, it's well worth getting a qualified tradesperson to do the job properly. You can find experienced local building inspectors and roofing tradespeople on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
BCITO Qualified
