Cooked from both sides
Northern roofs age from above. Florida roofs age from above and below at the same time, because the attic under a summer sun becomes a second heat source pressed against the underside of the deck. That is why identical shingles live shorter lives here, and why the attic belongs in every roofing decision.
- 1 Ridge and exhaust — Where the attic is supposed to breathe out. Sized in 1975 on half this arc.
- 2 The shingle field — The part everyone looks at. The sun works it from above, the attic from below.
- 3 The valley — Every afternoon’s rain, funnelled into one seam.
- 4 Wall flashing — Where the garage roof meets the house. Rebuilt metal outlives the shingles; caulk does not.
- 5 The vent boot — A rubber collar on a faster clock than the roof around it. The arc’s most common leak.
- 6 Eaves, drip edge and soffit intake — The hardware salt reaches first, and the intake the attic breathes through.
What the heat does from below
An unvented or badly vented attic in July holds afternoon temperatures far above the outdoor air, and that heat bakes the deck, the fasteners and the underside of the covering through every day of the season. The shingle warranty imagines a ventilated attic; the un-ventilated one spends that warranty early.
The houses that suffer most are the ones with rooms finished under the roofline and the plats whose venting was sized to the standards of their build year and never revisited, which describes a large share of this arc.
Replacement day is the repair window
Fixing airflow properly means working at the eaves and the ridge, and both are open exactly once: while the roof is off. Continuous intake at the soffits, an exhaust sized to match, and baffles holding the path open through the insulation cost little on that day and buy years of covering life.
The tell in a quote is one line: are the existing vents corrected, or reinstalled? Reinstalled means the question was skipped, and on an inland house that skip is the difference between a roof that reaches its rated life and one that quietly does not.