How long does roof decking last?
How decking breaks down
Plywood and OSB react to water differently. OSB tends to swell at the edges and lose strength where it stays wet, while plywood tends to delaminate, with its layers separating and sagging between rafters. Older homes built before sheet goods became common often have 1x6 or 1x8 board decking, and many of those boards are still sound because they were kept dry for decades.
Causes of early failure
- Slow leaks around pipe boots, chimneys and valleys that drip for years before a ceiling stain appears.
- Condensation from bath fans or dryer vents dumping moist air into the attic, or from an attic with too little ventilation. Humid Georgia summers make this worse.
- Missing drip edge, which lets water wick back into the deck edge and fascia.
Warning signs
From the attic, look for dark stains, mold spots, rusty nail tips and daylight at panel edges. From outside, a roof plane that dips between rafters or feels soft underfoot points to a weakened deck. A roofer will confirm it once the shingles are off, walking the bare deck and replacing sheets that are soft, delaminated or rotted.
Cost and coverage
Most estimates price decking replacement per sheet, so ask how many sheets are included and what each extra one costs. Rot from long-term leaks is usually treated as wear or maintenance rather than storm damage, so check your policy before assuming a claim will pay for it.
Learn the differences in OSB vs plywood roof decking and how airflow protects the deck in roof ventilation basics.