From the beachside suburbs of Cottesloe and Scarborough to the established properties up in Joondalup, living near the Perth coastline is a massive part of the WA lifestyle. However, the exact same sea breeze that cools your home on a hot January afternoon carries a silent threat to your roof’s structural health: airborne sodium chloride particles.
Coastal salt exposure, combined with our intense winter downpours, creates a highly corrosive environment for metal roofing components, particularly your roof valleys. A roof valley is the V-shaped metal tray running down the internal junctions where two different slopes of your roof meet. Think of your valleys as the main highways of your roof drainage system; during a severe storm, they channel five to ten times the volume of water handled by the rest of your roof.
When salt particles settle on these metal valleys, they mix with morning dew to form a highly concentrated corrosive solution that slowly eats away at the protective zinc or paint coatings. Once this barrier fails, raw steel is exposed, and rust takes hold. Because valleys sit deep beneath the edges of your roof tiles or metal sheets, this corrosion usually happens completely out of sight.
The danger of a rusted valley is that it cannot handle the high-velocity water flow of a winter downpour. The rushing water will find any pinhole rust leak, pouring directly into your ceiling cavity. To spot these early warning signs, do a ground-level visual check around your home. Look closely at the valleys for any flaky, orange-brown discolouration or bubbling paint work along the underside of your eaves. If the metal looks rough or uneven, the structural integrity of the valley tray is compromised. Replacing an aged, corroded valley tray during the dry autumn months is a straightforward maintenance task that completely eliminates the nightmare of a sudden, middle-of-the-night ceiling flood.