METAL ROOF LEAKS – FAMILY ROOFING

Posted on by David Reid

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At Family Roofing, we take great pride in our experience, expertise, quality and customer service. It is our mission to provide excellent workmanship and complete customer satisfaction from start to completion of a project. Our reputation is based on service, safety and quality, regardless of how large or small the job.

 

METAL ROOF LEAKS

When installed properly, a metal roof should last decades (40 to 70 years is a typical lifespan).  Still, there are a few issues which can cause a metal roof to leak, many of them having to do with mistakes made during installation.

Missing sealants 

Metal roof sealants that are installed in conjunction with a metal roof rarely last as long as the metal roofing panels do and need to be replaced with regular roof maintenance.  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.  Use a metal roof sealant specifically made for metal roofing.  Other types silicone caulkings may not adhere 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 breaking their seal.

Typically, sealants are installed at the same time as your metal roof.  The problem is sealants don’t last as long as the metal itself and will need to be replaced from time to time.   Checking the sealant should be a part of the regular maintenance routine for metal roofs, particularly around these areas:

  • Metal ridge caps

  • Z-flashings

  • Roof transitions

  • Counter flashings

  • Reglets

  • Pitch pans

It’s usually a good idea to have a roofing professional inspect the sealant in these areas and replace it as needed.  Only a sealant designed specifically for metal roofs should be used.  Typical silicone caulking doesn’t always adhere to roof surfaces and may not maintain its seal through all the expanding and contracting which can occur with metal roofs.

Curb Flashings 

HVAC units on Metal Roofs are usually sitting on curbs.  Installing metal roof panels is a relatively easy process but it’s the flashing that really test a metal roofers ability. HVAC offer little room for error when fabricating the flashing and keeping a curb dry can be easier said than done.  The up hill side of curbs and the two upper corners of the curb flashing are difficult areas especially on lager HVAC units. Water often gets trapped behind the unit and “stands “ behind the flashing which eventually erodes sealants and begins to leak.  The more you caulk, seal, or tar the uphill side the more water it will hold. This is difficult to remedy without removing metal roofing panels and starting over.

Stack Flashings

Stack flashings are the so-called “boots” or flashings in spots where pipes or vents come out of a metal roof.  Found around plumbing and air vents, they are typically made of rubberized material to form a seal around the pipe or vent.  These are some of the areas where a metal roof is most prone to leakage, partly because stack flashings have a lifespan of less than half that of the roof itself. Metal roofs are prone to expanding and contracting due to heat, and this puts a lot of strain on stack flashings over time.  Once they fail, the best option is to have stack flashings replaced by a qualified roofing expert.

Seams and overlaps 

There will inevitably be seams and places where panels overlap on a metal roof.  It’s absolutely crucial for these places to be properly sealed when your roof is first installed. Water can actually be drawn uphill, against gravity, through the forces of adhesion, cohesion, and surface tension.  This process is known as capillary action.  It can cause a metal roof to leak at its seams even if the overlapping seam is above the underlying panel.

Metal roofing screws 

Roofing screws are responsible for the majority of leaks on metal roofs.  Metal roofing screws seal water out by compressing a rubber washer at the base of the screw head.  When the screw is driven into the metal roofing panel the rubber washer forms a “gasket” between the roofing panel and the screw head.  It sounds simple enough but several things can go wrong like under driving screws, over driving screws, driving screws at the wrong angle and screws that missed the framing member.  The roofing screws used to install metal roofs include a rubber washer at the base of the screw head.  The washer forms a gasket of sorts between the roofing panel and the screw.  It’s a simple design which, when done right, does a great job keeping water from penetrating your metal roof.

Unfortunately, there are a number of things which can go wrong with roofing screws.  This is why it’s so essential to have your metal roof installed by only the most qualified roofing experts.  Common roofing screw issues include:

  • Under-driven screws

  • Over-driven screws

  • Misaligned screws

The only way to identify leaky roofing screws is a detailed visual inspection by a roofing expert.  Even if your metal roofing screws were driven in just right, it’s still a good idea to have them looked at every few years, because they can “back” out over time due to wind, vibrations, and roof shifting.

The first step to fixing leaks in a metal roof is identifying the underlying cause.