As you can see, the vent in question cuts through a Colorbond (steel) roof top. Its contact with the roof is sealed with silicon.
My question is: what do I need to know about the maintenance? Can the silicon age and become brittle, and eventually let the water in?
What are the maintenance must-do I need to be aware of?
This is something you need to inspect yearly. The right edge of the flashing appears to be lifting up and should be sealed down so wind doesn't lift it up further. Silicone is a great sealer and isn't normally affected by heat and aging. Use a quality silicone meant for roofing and you should be good for years but still do a yearly inspection.
Regular silicone exposed to sun can become brittle.
Use the UV resistant silicone to refill.
The roofer cut a pice of the roofing material and made the cover, which is fine.
The left and right show gap, and need silicone filling.
What is important to maintain is the middle part and around the actual vent cut.
