The flashing serves as your roof’s primary defense where shingles or panels are least effective: at the seams. No matter how seamless your roof may look, there will always be gaps along each roof plane’s edges. The roof flashing covers these seams so that your entire roof system forms a single, watertight blanket over your home.
Leaks caused by poor flashing can best be explained by the following analogy: imagine that the roof is like an split dome or umbrella that can be separated along its sections, and the flashing is like a layer of duct tape joining these sections together. If the duct tape is removed, water can penetrate the dome by running along the space between each section.
Unfortunately, your roof’s flashing receives just as much punishment as the roof’s outer surface. If asphalt shingles tend to curl up over time and metal roof panels develop rust, flashing can get warped out of shape by constant changes in temperature, if not knocked out of place by debris or even a minor shift in one of the roof planes.
One of the best ways to check if a leak is caused by faulty flashing, is by determining the location of the leak. Normally, you’d check the spot directly above the roof leak, but sloped roofing designs mean that water dripping down one spot of the ceiling may originate from a different part of the roof up to a few meters away. This is why roof leaks caused by faulty flashing are better off inspected by someone with actual roofing experience.
Flashing repair is often a straightforward process; the damaged part is lifted before the existing sealant is cleaned out, and then the gap is filled, the flashing is either put back in place or replaced entirely, and caulking is reapplied. While this may be a simple task when repairing smaller flashing problems (especially chimney and vent flashing), bigger ones such as repairing valley flashing or total replacement is usually best left to professional roofers.
Your flashing is fixed, but your home isn’t 100% leak free yet! Find out another major cause of leaks in Part 3 of this blog series, coming soon!