Owning a home means staying on top of the maintenance of many things including a metal roof to get ahead of leaks. Metal roofs, although the strongest roofs around, are not indestructible. They are made from different types of metals, therefore, your selection will be dependent on your budget.
There are several reasons why these types of roofs can leak and need repair.
Metal Roofing Screws
These screws seal water out by compressing a rubber washer at the base of the screw head which then forms a gasket so to speak when the screw is driven into the metal roofing panel.
The majority of time metal roof leaks are formed as a result of incorrectly installing roofing screws, screws that have missed the framing, or screws that have weakened over time.
Metal roofing panels will far outlast the sealants used so sealants will need to be replaced with regular roof maintenance. Check for wear and tear of the sealant. Should the sealant need to be topped off be sure to purchase a sealant specifically made for metal roofing.
Why? Because the flashing on a metal roof can be a challenge for even the most experienced metal roofer especially if there is a HVAC unit, which usually sits on curbs, on the metal roof.
The end game is to keep the curb as dry as possible so the flashing needs do be done with precision. If water gets trapped behind the HVAC unit and settles behind the flashing, eventually the sealants erode and a leak starts.
Stack flashings (the material used to waterproof the HVAC vents, air vents and plumbing pipes which wall have to vent through the roof) is another area where you’ll find a lot of leakage on a metal roof .
Most stack flashings are made or rubberized material that sits flat on the metal roof and forms a seal around the pipe. Due to the movement in a metal roof from expansion and contraction, as well as the sun beating down on it these flashings generally last about half the time as the roof itself.
Seams and Overlaps
Seams where two pieces of metal roofing overlap each other often leak because of capillary draw, or the process by which water actually travels uphill between two tightly joined pieces of metal. Placing sealant between the two pieces of metal can break the capillary draw. But if not used correctly, it can actually make leaks worse than if you had never used it at all.
You can check the Pros and Cons from an insurance perspective HERE