Roof Replacement Timeline Calculator

Expected Lifespan is Roofing Material's base lifespan (25 years for Asphalt Shingles up to 100 for Slate) multiplied by a Climate Zone factor (0.80 in the harshest zones up to 1.00 in the mildest) and a Maintenance Level factor (0.80 for Poor upkeep up to 1.15 for Excellent). Roofing Material dominates that result -- its 4x spread between the shortest- and longest-lived materials moves Expected Lifespan far more than Climate Zone's roughly 20% swing or Maintenance Level's roughly 35% swing. Roof Age never enters the Expected Lifespan calculation at all; it only gets subtracted from Expected Lifespan afterward to produce Years Remaining, and Roofing Material still dominates Years Remaining too, since a material with a much longer base lifespan carries most of that extra life straight through into the remaining- years figure.

Condition Score expresses Years Remaining as a percentage of Expected Lifespan (0 to 100), and Urgency translates that score into plain language, from "Good -- no action needed" at 60 and above down to "Immediate -- replace now" below 10. This is a statistical estimate based on typical material lifespans, not an inspection -- it can't detect storm damage, leaks, or workmanship problems that shorten a roof's real remaining life.