Ask a homeowner what part of the roof leaks and the answer is almost always the shingles. Ask a roofer and the answer changes. Water gets into North Texas houses through the joints far more often than through the field of the roof, and the material responsible for those joints is flashing. Flashing is thin metal, usually galvanized steel or aluminum, installed anywhere the roof plane stops or something passes through it. Chimneys, walls, valleys, vent pipes, skylights, and the edges of the roof itself all need it. Shingles shed water across an uninterrupted surface. Flashing handles every place where that surface is interrupted, which is where the water has somewhere to go besides down. The failure happens on a shorter clock A laminated shingle in this region has a practical life somewhere around twenty years. Several of the flashing components on the same roof do not last that long, and the mismatch is what catches homeowners out. Rubber pipe boots are the clearest example. A standard boot uses an EPDM collar that seals around the plumbing vent stack. In the Texas sun that rubber takes ultraviolet exposure with no shade and no relief, and it typically starts cracking somewhere between year eight and year twelve. The shingles around it still look fine. The boot has split open at the top of the collar, and every rain since then has been running down the outside of the pipe into the attic. This is the most common leak a roofer gets called out for in Denton County, and it is also the cheapest to fix if someone catches it early. Left alone, it soaks the decking around the penetration, then the insulation, then eventually a ceiling. Chimneys and wall intersections Where a roof meets a vertical wall, the correct assembly is two pieces. Step flashing goes under each course of shingles and turns up the wall. Counterflashing either sits in a groove cut into the masonry or tucks behind the siding, and it laps over the step flashing so water cannot get behind it. What frequently shows up instead is a bead of roofing cement smeared along the joint. Sealant is not a flashing method. It has a service life of a few years in this heat, it shrinks as it cures, and it hides the problem it is supposed to solve until the drywall inside gives it away. Any chimney with a visible black smear around its base is worth a closer look. Chimney crickets are the related omission. A chimney wider than about thirty inches needs a small peaked structure on the uphill side to divert water around it. Without one, debris and water pile against the back of the masonry and sit there. On homes built quickly during a growth period, the cricket often never got installed. Valleys A valley is where two roof planes meet and concentrate runoff. It moves more water per square foot than anywhere else on the roof, which makes it unforgiving. There are two accepted approaches. An open valley uses a metal channel down the center with shingles cut back on both sides. A closed valley weaves or laps the shingles across. Both work when installed correctly. Both fail when the underlayment beneath them is inadequate or when shingles are cut short and the sealed edge is missed. Valley problems tend to reveal themselves slowly. The water does not drip into a room right away. It tracks along a rafter and shows up feet away from where it entered, which is why homeowners sometimes chase the wrong spot for a season. Drip edge and the roof perimeter Drip edge is the L shaped metal at the eaves and rakes that pushes water off the roof and into the gutter rather than letting it curl back under the deck. It is inexpensive, it is required by most current building codes, and it is left off more often than it should be, especially on older houses and on budget reroofs. The symptoms are easy to see from the ground once you know to look. Rotted fascia board, peeling paint along the eave, and gutters that seem to overflow even after cleaning often trace back to a missing or poorly lapped drip edge rather than to the gutters themselves. Why reroofs repeat the problem The economics of a roof replacement push in one direction. Tearing off shingles and installing new ones is the visible part of the job. Replacing flashing costs material and labor that the homeowner cannot see afterward, and it is the easiest line to quietly leave out of a bid. So old pipe boots get reused under new shingles. Old step flashing stays on the wall. The chimney counterflashing never gets reset. The roof looks new from the curb and carries components that are already most of the way through their life. Two or three years later there is a leak on a roof that came with a warranty, and the conversation about what that warranty covers gets uncomfortable. The way to avoid it is to ask before signing. A bid that lists new pipe boots, new step and counterflashing, new valley metal, and new drip edge as separate items is a bid from someone who intends to do the work. A bid that says “replace roof” and nothing else leaves all of that open. Roofers such as the team at Epic Roofing & Construction itemize those components for exactly that reason, since the difference between the two approaches does not show up for years. What a homeowner can watch for Most flashing problems are visible without a ladder if you know where to point your eyes. From the yard, look at the base of every chimney and every place a roof plane runs into a wall. Black sealant, rust streaks, or a gap you can see from the ground are all worth a call. Scan the eave line for soft or discolored fascia. In the attic, check the underside of the deck around each plumbing vent for staining, since that will show long before a ceiling does. Inside the house, a stain that appears in the same spot after heavy rain but stays dry the rest of the year is almost always a joint rather than a field failure. Pinning down where the water enters takes someone on the roof, but knowing it is a flashing question narrows the search considerably. The practical takeaway Roofs in North Texas rarely fail all at once. They fail at the seams first, on a clock that runs faster than the one printed on the shingle wrapper. Checking the penetrations every few years, and insisting that flashing components get replaced rather than reused during a reroof, costs very little compared with repairing a ceiling and the framing above it. It is unglamorous maintenance on a part of the roof nobody photographs, and it prevents most of the leaks that actually happen. The post Why Roof Flashing Fails Before the Shingles Do appeared first on The Rocky Mountain Collegian.
