You may have learned by now that I’ve never been known for brevity. This blog post, however, should buck that trend a little bit. Why? Simple, because this common error is very easy to identify and resolve. So easy, in fact, that it doesn’t make much sense why these things are almost never done properly in the first place.
The scenario is this: Any time an out side wall corner or an inside wall corner comes down to intersect with a roof plane, assume it’s not flashed properly. Now, this does not mean that it leaks, necessarily. It may not leak due to a proper insurance layer of ice and water shield underneath the shingles. Conversely, the lack of water signs inside the corresponding portion of the home does not mean that it is not leaking. Wood, especially real wood as opposed to “particle board”, has the ability to absorb water, and then dry out. This can happen over and over again, as long as it can dry out. Or, The initial plywood and framing components that are coming in contact with the water that is infiltrating are sometimes not able to properly dry out, and thus rot. The components that lay below these “first absorbers” will get wet, but not necessarily beyond their saturation point. If the lower levels of wood are absorbing the water without exceeding their saturation point, the water may never make it to the drywall layer to display to the homeowner that damage is being done. This explains how a home can be taking on water without showing signs of it on the drywall, for instance.
What is the error at these corner/roof intersections that is causing these problems? Well, the lack of incorporating nice, wonderful, beautiful, malleable lead flashing into the mix. Am I in love with lead? Maybe just a trifle, but hey, what’s not to love? Standard aluminum step flashing runs up the abutting cheek wall that the roof shingles butt into. And aluminum can sometimes also be used to flash the siding down over the roofing at those wall planes that run parallel with the shingles. But what aluminum cannot ever do is to turn that corner seamlessly. Lead, however, has the ability to hit all these multiple planes seamlessly. Mmmmmmmmm.
It’s comical the things that I sometimes see. I will pull apart these layers to correct and end up seeing layer after layer after layer after layer of aluminum flashing. Each one torn right at the crux of the corner, every time. So, the predecessor’s solution for recognizing that the flashing was tearing: Keep throwing more layers at it. Awesome.
These are flaws that are easy to identify, simple to fix yourself if you’re comfortable on a roof, or inexpensive (unless there is widespread rot) to hire a professional to solve. It may only cost $200- $300 to un-weave some shingles, remove a corner board, install some lead flashing, install a new corner board, and weave the shingles back in. The most difficult challenge you may face might be finding the professional that knows how and when to incorporate lead flashing. Here’s a catchy little reminder when vetting a repair contractor: Find someone with a passion for flashin’. No. I won’t be quitting my day job any time soon.
I must leave you with one last tidbit of information. I mentioned that aluminum can usually be a good flashing choice for the planes that don’t need to wrap around a corner. When it’s not a suitable choice is when there is copper in the vicinity. Copper is ranked higher on the Galvanic Scale of Nobility and blah, blah, blah. Anyway, copper and water runoff from copper interact with aluminum and cause the aluminum to rot right out. That’s also why aluminum is no longer acceptable to use as a deck flashing, because pressure treated lumber is treated with copper. Now you’re prepared to go tackle this one, safely of course.
By John Bradshaw