When it comes to roofing materials, there are few choices that offer the durability and performance of metal. They’re the strongest roofs around, but that doesn’t mean they’re indestructible. Metal roofs can come in many different shapes and sizes. The types of metal used in roofing all have different pros and cons, what you decide to select is more than likely due to your budget.
There are several reasons why these types of roofs can leak and need repair.
So if you have a metal roof, be on the lookout for any of the following reasons why repairs may be needed:
Metal Roofing Screws
The majority of leaks on metal roofs are formed as a result of roofing screws that were either installed incorrectly or that have weakened over time.
These types of screws seal water out by compressing a rubber washer at the base of the screw head, which forms a type of gasket when the screw is driven into the metal roofing panel.
Typical things that can go wrong include under driving screws, over driving screws, driving screws at the wrong angle and screws that completely missed the framing.
Metal roof sealants hardly ever last as long as metal roofing panels do, so they will need to be replaced with regular roof maintenance.
Sealants all need to be topped off from time to time, as they will experience a good amount of wear and tear.
If you do need to make this type of replacement, be sure to use a sealant specifically made for metal roofing, as silicone caulking may not adhere to the paint on the roofing panel and trims.
Installing metal roofing panels is really not all that difficult, but the flashing that goes along with it can be a challenge for even the most experienced metal roofer.
HVAC units on metal roofs are usually sitting on curbs and there’s little room for error when fabricating the flashing. And keeping a curb dry can be extremely difficult.
Water can often get trapped behind the HVAC unit and remain behind the flashing, which eventually erodes sealants and begins to leak.
The more you caulk or seal the uphill side, the more water it will hold. But it’s difficult to remedy these types of problems without removing the metal roofing panels and essentially starting over.
Another area where you’ll find a lot of leakage on a metal roof is an area known as stack flashings, which is the material around the pipes that come out of the metal roof.
HVAC vents, air vents and plumbing pipes all have to vent and come through the roof and the stack flashing is how the pipe is waterproofed.
Most stack flashings are made or rubberized material that sits flat on the metal roof and forms a seal around the pipe.
The movement in the metal roofing from expansion and contraction, as well as the sun, continually test these flashings, which generally last only 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.