Edge Flashing for Dummies

Edge flashing for a roof

Around the Antisocial Network, we know that a homeowner's most dangerous enemy is water. It doesn't have to be a flood, though, because water is nothing if not patient. Any building that isn't carefully sealed is gonna leak, the leaks are gonna cause wet wood, and the wet wood is gonna rot. Over the centuries, builders have figured out that one way to keep water away from the wood is to use metal flashing to prevent water from penetrating. That's why your home's roof has different kinds of flashing in different places. If you think it needs more, though, you'd better not ask the likes of HomeSteady.com's Missy Farage questions like, "How do I Install an Edge Flashing on a Patio Roof?"¹

A BA in Creative Writing or no, Farage was clearly out of her depth here. She was right, of course, when she opened her post by explaining that,

"Your roof is one of the most important parts of your home. Whether it is your patio roof or your house's roof, unprotected edges of a roof can lead to rot and decay, undermining the efficiency and integrity of the structure. Therefore, it is important to make sure that all edges of your roof are protected."

She was also on point when she informed her readers that,

"The simplest way to do this is to cover them with metal edge flashing..."

It's after that point, however, that Melissa made it abundantly clear that she had no idea what she was talking about. What she should have said was that a builder will install drip edge on the end and sides of the roof (the rakes). This metal flashing extends beneath the roofing, preventing water from "curling" back under the shingles to spread moisture on the decking and rafters. Instead, what Missy wanted her readers to do is,

• "If the measurements of the patio roof are longer than the pieces of the edge flashing, lay whole pieces of edge flashing end to end, and cut a smaller piece to fit the remaining space."
• "Lay the edge flashing by beginning at one corner of the roof. Place the pieces of edge flashing on the front lower edge of the roof. Hammer in 1 1/4-inch electrified [sic] iron nails, spacing the nails at 2-inch increments. "
• "Create a butt joint on the corner of the roof by overlapping the two pieces of edge flashing. "

Oddly, none of those steps are in Farage's sole reference, which we found to be mostly about flashing in valleys and around chimneys with but a brief mention of drip edge. For that matter, Missy never mentioned drip edge, either. And that business about "electrified iron nails"? WTF was that – her understanding of "electrogalvanized"? Whatever the case, Farage never said a word about extending the flashing beneath the roof material, never said a word about roofing cement, and in general made it pretty darned obvious that she had no idea what she was talking about. Are you thinking Dumbass of the Day? We are...

¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was   homesteady.com/how-6894198-do-edge-flashing-patio-roof-.html

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