An aging roof
A roof rarely fails on a single day. It gets close over several years, and then one wet season finds the weakest point.
- 1 Ridge caps. Thin, fully exposed, and the first course to lift.
- 2 The field. Granule loss is the honest measure of how much life is left.
- 3 Valleys. One channel taking the runoff of two slopes, all year round.
- 4 Flashing. At the chimney, and where the garage roof meets the wall of the house.
- 5 The vent boot. Small, rubber, and on a much shorter clock than everything around it.
- 6 Eaves. Where water that has backed up at the edge gets under the courses.
Granules in the gutters
The mineral surface on an asphalt shingle protects the asphalt from ultraviolet light. A new roof sheds a little loose material in its first months. A roof that is filling the bottom of a downspout with granules year after year is losing its protection, and the asphalt underneath hardens and cracks once it is exposed.
Curling, cupping and cracking
Edges lifting away from the roof, corners turning up, or shingles that look wavy across a whole slope all indicate the mat has lost flexibility. A shingle in that state cannot seal to the one below it, which means the next wind event has something to catch.
Uniformity matters. Damage in one area is a repair. The same appearance across an entire slope is the roof telling you its age.
Whole streets come due together
In developments built out in a single phase, much of Fairfax, Ashburn, Nottingham, Bel Air, the roofs went on within a couple of years of each other and reach the end of their life within a couple of years of each other. One neighbor replacing a roof is frequently followed by several more on the same block within a season, and it is a reasonable prompt to have your own looked at.
The census puts numbers on how differently two ends of this market age. In Arlington, roughly a third of the housing was standing before 1960; twenty miles west in Loudoun County that share is under four percent, and closer to six homes in ten arrived after 1990. One site, two roof calendars with almost nothing in common.
The streaks, which are not what they look like
One caution about reading age off a roof from the street. Dark streaks running down the north and shaded slopes are close to universal on Maryland and Northern Virginia housing after the first decade, and they are not the shingle wearing out. They are a growth that feeds on the limestone filler in the mat and shows against the granule color, which is why it streaks downward and why it favors the slope that dries slowest. A roof can be heavily streaked with most of its life ahead of it.
The reason it is worth naming is that people replace on it. A streaked roof looks finished from the driveway, and a covering with eight good years left gets torn off because of how it photographs. The signals that actually count are the ones above: what is in the gutters, whether the edges have gone hard, what the boots look like. Cleaning is a separate question with its own trade-offs, and the honest sequence is to establish the roof’s condition first and treat the appearance second, rather than letting the appearance decide the condition.