ROOFING REPAIRS – EDMONTON AB
METAL ROOF REPAIRS
Very few roofing products surpass metal roofing when it comes to durability, strength, and performance. Don’t let a metal roof’s superiority fool you – sometimes, not often, they can leak.
Below are the reasons why this can potentially happen:
Metal roofing screws
Roofing screws are the most common cause of leaks on metal roofs. At the screw head base, metal roofing screws are able to seal water out by squishing a rubber washer. The rubber washer forms a “ gasket” between the roofing panel and the screw head when the screw is drilled into the metal roofing panel. Though this sounds simple, and problem-free, several things can go wrong. For example, under driving screws, over driving screws, driving screws at the wrong angle and screws that missed the framing member.
The area around stack flashings are very prone to leaks on a metal roof. Stack flashings are the flashings around pipes (such as HVAC vents, air vents, and plumbing pipes) that protrude through the metal roof. The pipe is water proofed by the stack flashing. Most stack flashings are rubber material that sits on the metal roof forming a waterproof seal. The movement in the metal roofing from expansion and contraction is taxing on these seals.
The sun also degrades the rubber flashings which usually lasts half as long as the metal roof. The more caulking, sealant, or tar that is placed behind and around the stack the more they seam to pond water and leak.
A metal roof will usually outlast its metal roof sealants. The Sealants under trims such as metal ridge caps and Z flashings, around roof transitions, counter flashings, reglets, and pitch pans will all need to be “topped off” from time to time as they wear. A metal roof sealant is made specifically for metal roofing and should be the only sealant used as other options like silicone caulkings may not adhere properly to the paint on the roofing panel and trims. Metal roofing goes through a daily expansion – contraction cycle and if any sealants are to last, they must be able to remain flexible and stretch with metal without the seal breaking.
HVAC units on Metal Roofs are usually sitting on curbs. The flashing really tests a metal roofer’s capabilities. HVAC offer little room for error when fabricating the flashing and keeping a curb dry can be tough task. There are specific areas of the curb flashing that are very tough, particularly on larger HVAC units. Water can get trapped behind the unit and sits behind the flashing which ultimately erodes sealants and begins to leak. The more you caulk, seal, or tar the uphill side the more water it will hold.
Seams and over laps
A condition called capillary draw is where seams with 2 pieces of metal roofing over lap each other often leak. Capillary Draw is when water travels up hill between two tightly joined pieces of metal. Sealant or butyl tape between the two pieces of metal can break the capillary draw but if not used correctly can actually make leaks worse than if none had been used at all.