Roof Life Calculator

Expected lifespan starts from well-established material baselines — 25 years for asphalt shingles, 50 for metal, 60 for tile, 100 for slate, and 30 for wood shake — then gets adjusted by two environmental multipliers. A mild climate stretches expected life by 10%, while a harsh climate (extreme heat, cold, hail, or hurricane exposure) cuts it by 25%, since freeze-thaw cycling and UV load are the main drivers of shingle and membrane degradation over time. Tree overhang applies a separate penalty on top of that — up to 20% off for significant overhang — because falling debris, abrasion, and moss or algae growth from trapped moisture all shorten roof life independently of climate.

Years remaining is simply the adjusted expected lifespan minus the roof's current age, floored at zero so an already-overdue roof doesn't show a negative number. Replacement urgency and inspection frequency are both driven by the same underlying ratio — how much of the adjusted expected lifespan has already elapsed — rather than by raw age: a roof at 90%+ of its expected life gets the highest urgency score and the tightest 6-month inspection cadence, while one under 50% gets the loosest, 24-month cadence. The key assumption to know is that these are actuarial averages for the material category, not a substitute for a physical inspection — a well-installed, well-ventilated roof can outperform its category baseline, and poor installation, inadequate attic ventilation, or storm damage can shorten it well below these estimates regardless of what the calculator shows.