FREE QUOTESkylights and roof lights do a lot for a commercial building. They cut down on daytime lighting costs, improve conditions for staff working in warehouses and factories, and make retail spaces feel brighter and more welcoming. They are also quite consistently one of the most common points of failure on an otherwise sound commercial roof. Understanding why that happens, and what good skylight installation and maintenance actually looks like, can save a business owner a lot of frustration and a fair amount of money over the life of the roof.
Why Skylights Fail More Often Than the Surrounding Roof
A skylight is essentially a break in an otherwise continuous roof surface, which means it relies entirely on flashing, sealant, and correct detailing to stay watertight. Unlike a flat run of Colorbond sheeting, a skylight has edges, joints, and often a different material entirely, such as polycarbonate or fibreglass, meeting the metal roof around it. Every one of those junctions is a potential entry point for water if it has not been installed correctly or has degraded over time.
Common causes of skylight leaks on commercial buildings include:
- Perished or UV-degraded sealant around the skylight edges
- Flashing that was not correctly lapped or fixed during installation
- Ponding water sitting against the skylight base due to poor roof drainage nearby
- Thermal expansion and contraction gradually working fixings loose over years of use
- Debris build-up around the skylight base trapping moisture against the seal
Choosing the Right Roof Light for the Application
Not every skylight product suits every commercial building. Warehouses and factories often use polycarbonate roof lights matched to the same profile as the surrounding Colorbond sheeting, allowing them to be installed as part of a continuous run rather than a separate cut-in unit. Retail and office buildings might use a different style entirely, depending on whether the goal is general daylighting or a specific architectural feature. Getting the profile match and material selection right at the outset makes a real difference to how well the skylight performs and how easily it can be replaced later if needed.
Where Skylights Fit Into a Roof’s Broader Health
Skylights rarely fail in isolation from the rest of the roof. Poor drainage nearby, for example, can leave water sitting against a skylight base for longer than it should, accelerating wear on the seals. This is one of the reasons drainage design matters across the whole roof, not just around the skylights themselves, something we covered in our guide on commercial roof drainage in Melbourne. If your building has drainage issues, it is worth checking whether skylights nearby are showing early signs of stress as a result.
How Often Skylights Should Be Checked
Because skylights age differently to the surrounding metal sheeting, particularly if they use polycarbonate rather than steel, they need their own place in a regular inspection routine rather than being assumed fine just because the rest of the roof looks sound. A proper roof inspection should always include a specific check of skylight seals, flashings, and surrounding drainage. If you are unsure what a thorough inspection actually involves, our article on what actually happens during a professional roof inspection in Melbourne explains the process in detail.
Repair, Reseal, or Replace
When a skylight starts showing signs of leaking, the right response depends on how far the problem has progressed. Early sealant failure can often be addressed with a proper reseal, while degraded polycarbonate that has yellowed, clouded, or become brittle usually needs to be replaced outright rather than patched. Trying to reseal a skylight that has already failed structurally is a short term fix at best, and one that tends to need repeating within a year or two.
Getting Skylights Right the First Time
Skylights are a small part of a commercial roof by area, but they carry an outsized share of the leaks we get called out to fix. Our team has extensive experience across commercial roofing projects throughout Melbourne, including skylight installation, repair, and replacement as part of broader roofing work. If your building has skylights that are ageing, leaking, or simply due for a proper inspection, contact us and we can assess them alongside the rest of your Colorbond roofing system.