Whether you’re working with steel roofing or another material, flashing is one of the most important components in keeping a roof weatherproof. These angled metal pieces seal joints, edges, and penetrations — such as chimneys, skylights, and roof valleys — to help direct water safely away. In steel roof systems specifically, flashing includes ridge, barge, verge, eaves, and corner flashings, all custom-shaped to cover exposed sections and prevent leaks.
Over time, even the most well-installed flashings can start to fail. Here’s how to spot the warning signs — and what to do next.
Rust or Corrosion
With metal flashings — especially steel — rust is a common issue, often due to scratches, pooling water, or worn coatings. Early signs include discolouration, flaking, or bubbling under the paint layer. While minor surface rust can sometimes be treated, deeper corrosion usually means it’s time to replace the section.
Leaks or Damp Patches
Unexpected moisture indoors — whether near a skylight, along a wall, or beneath a ceiling corner — can point to flashing failure. In both traditional and steel roofing systems, flashing helps guide water away from vulnerable points. Ridge, verge, and eaves flashings on a steel roof, for example, all work together to maintain drainage. If water’s sneaking in, it’s worth having your flashing professionally inspected.
Gaps, Lifting or Loosened Sections
Flashing should sit tightly sealed to the roofline. If you notice lifting edges or visible gaps, water and debris can work their way underneath. This can be caused by thermal movement, but also by loose fixings, poor sealing, or even poor installation. Any movement or separation is a clear sign that replacement may be needed.
Cracks or Splits
Temperature changes cause all flashing materials to expand and contract. If flashings were installed without proper allowances for thermal movement — particularly on steel roofs — the resulting stress can cause cracks or splits over time. These small breaks can let in moisture and worsen quickly with weather exposure.
General Wear and Tear
Even if your flashings look fine from the outside, age and long-term weather exposure take their toll. After around 20 years, flashing materials — whether steel, lead, or aluminium — may start to degrade, become brittle, or lose their seal. If your roof is approaching that age, it may be wise to proactively upgrade the flashings to avoid future issues.
What To Do Next?
If you spot any of these signs, don’t panic. Replacing flashings is a lot easier (and more cost-effective) than repairing water damage. And if you're already replacing steel sheets or other roofing accessories, it’s the perfect time to upgrade your flashings too.
Southern Sheeting offers a full range of steel flashings and steel roofing accessories, with expert advice to help you find exactly what you need — whether you're replacing a single section or upgrading your full system.
