1. Article Body
Most people think about their roof twice: when it leaks and when they sell. Understanding it in between is what makes both of those cheaper.
A roof is an assembly, not a covering
Deck, underlayment, flashing, covering, ventilation. Five parts, and the one you can see from the street is only one of them.
The deck is the structural surface. The underlayment is the actual water barrier. Flashing seals every place the roof meets something else. The covering sheds the bulk of the water and protects everything below it from sunlight. Ventilation moves air through the space beneath so the assembly stays dry.
Failures in the covering are visible and usually cheap. Failures in the underlayment and the flashing are invisible and usually expensive.
The attic is part of the roof
Half of what goes wrong with a house roof announces itself in the attic first.
Staining on the underside of the deck, daylight showing through, compressed or damp insulation, frost on nails in cold weather, and blocked soffit vents are all roof findings, and all of them are visible without a ladder on the outside.
A homeowner who checks the attic twice a year catches most problems while they are still small.
Ventilation decides lifespan
Intake at the eaves, exhaust at the ridge, and enough of both.
Without it, the attic overheats in summer, which ages the covering from beneath, and holds moisture in winter, which attacks the deck. Blocked soffits caused by insulation pushed into them are extremely common and completely fixable.
Where a roof is failing early with no other explanation, ventilation is usually the reason.
The four decisions you will face
Repair or replace. Driven by whether the failure is one detail or the whole system, and by how much life the covering has left.
Which material. Driven by climate, pitch, structure, budget and how long you intend to stay.
Whether to claim. Driven by cause, deductible and claim history.
When to do it. Driven by condition, not by a salesperson at the door.
What to keep
A file with the installation invoice, the warranty registration, the permit, every inspection report and dated photographs.
It settles a warranty question, it defeats a wear and tear argument on an insurance claim, and it answers a buyer's questions at sale without a negotiation. It costs nothing to keep and it cannot be recreated later.
Where to start today
Go into the attic with a flashlight on a bright day and look up. Then walk the perimeter outside with binoculars.
Between them you will learn more about your roof in twenty minutes than a sales visit will tell you.
