FREE QUOTEAsk most people what determines how long a commercial roof lasts, and they will talk about the sheeting, the coating, or the thickness of the steel. Very few mention the fasteners, yet these small components are involved in a disproportionate number of the roof problems we get called out to fix. On a large commercial roof, there can be thousands of individual fixing points, and each one is a potential entry point for water if it is not the right type, correctly installed, or properly maintained over time. This article looks at why fasteners deserve more attention than they usually get.
What a Fastener Is Actually Doing
Every screw or fixing on a Colorbond roof has one job beyond holding the sheet in place: keeping water out at that exact point. This is usually achieved with a sealing washer that compresses against the sheet as the screw is driven in, creating a watertight seal around the hole. When that seal is compromised, whether through the wrong screw, poor installation, or simple age, water has a direct path underneath the roof at that point, often well before any visible sign shows up from below.
Choosing the Right Fastener for the Job
Not every fastener suits every application. Factors that determine the correct choice include:
- The type of substrate being fixed into, whether steel purlins, timber battens, or an existing roof structure during a re-roof
- The gauge and length required to achieve proper penetration without over-driving
- Corrosion resistance suited to the site’s environment, particularly for coastal or industrial buildings
- Compatibility with the sheeting material, since mismatched metals can accelerate corrosion at the fixing point
- The correct washer type to maintain a reliable seal over the roof’s expected lifespan
Using a generic fastener because it happens to be on hand, rather than the one specified for the job, is a common shortcut that tends to show up as leaks years later rather than immediately.
Installation Technique Matters as Much as Fastener Choice
Even the right fastener can fail if it is not installed correctly. Over-driving crushes the sealing washer and destroys its ability to seal properly, while under-driving leaves a gap that water and wind can work into over time. Fasteners also need to be placed in the correct position relative to the sheet profile, typically on the crest rather than the valley, to avoid sitting in a spot where water naturally collects. This is exactly the kind of detail that separates an experienced commercial roofing crew from a less specialised installer, and we covered several related installation issues in our article on installation mistakes that can void a Colorbond warranty on commercial roofs.
Why Fasteners Age Differently to the Roof Around Them
Sealing washers are typically made from a different material to the steel sheeting itself, often a synthetic rubber compound, and these materials degrade at their own rate depending on UV exposure and weathering. It is entirely possible for the surrounding Colorbond sheeting to still be performing well while fasteners nearby have started to fail, which is why a roof inspection needs to include a proper check of fixing points specifically, not just a general look at the sheeting from a distance.
The Cost of Ignoring Small Fastener Failures
A single failed fastener rarely causes a dramatic leak on its own, which is part of the problem. Water tends to enter slowly, tracking along purlins or insulation before it becomes visible inside the building, by which point some damage has often already occurred. Left unaddressed across a large roof, small fastener failures accumulate into a much bigger repair bill than if they had been caught and replaced early. Our article on the real cost of delaying commercial roof repairs in Melbourne covers this pattern in more detail, and fasteners are a common contributor to that story.
Getting the Small Details Right
Fasteners might be the smallest component on a commercial roof, but they are far from the least important. Our team treats correct fastener selection and installation as a standard part of every commercial roofing project, not a detail to rush through. If your roof is due for an inspection or you suspect fastener issues may be contributing to a leak, contact us and we will assess your Colorbond roofing system properly, right down to the fixings.