Colorbond and Zincalume metal roofing is a fantastic product to protect your home against the elements. Not only does it look great, it does a better job than tiles of keeping dust and debris out of your ceiling cavity. Like anything though, you should periodically check it for signs of wear or degradation.
The most common source of metal roof leaks is rust. Colorbond and Zincalume are essentially steel sheet coated with corrosion preventing materials. Over time, these coatings break down, exposing the steel underneath. Once the steel begins to rust or oxidise, the sheets become thinner and thinner until they develop a hole.
Look for discoloured areas and incorrectly installed evaporative air conditioner drains.
Older roofs were fixed using nails instead of screws. Over time, the expansion and contraction of the wooden battens underneath can push the nails away from the roof. This creates a gap where water can enter the ceiling space around the nail hole.
Look for raised or missing nails.
Flashings seal the edges of roof sheets and prevent water from entering the roof. Sometimes flashings are incorrectly installed, resulting in the flashing moving and no longer covering the roofing sheets.
Look for broken rivets, loose flashings and raised screws.
Different roof sheets require different minimum pitches to effectively drain water. As the roof ages, the battens can sink creating different pitches within a roof. As a result, some roofs cannot drain enough water in heavy rain. The water pools up and can ingress around flashings and low points. As a rule of thumb, Kliplock roofs require a minimum of 1 degree pitch, and corrugated roofs require 5 degrees.
Look for pooling water, soft battens and areas where the pitch is below minimum.