How long does roof decking last?
What damages decking
- Long-term leaks: a slow leak at a pipe boot or flashing can soften a sheet over months without showing on the ceiling.
- Attic condensation: warm, moist air reaching the cold deck in winter, common when bath fans vent into the attic, causes dark staining, mold and delamination.
- Edge rot: missing drip edge or overflowing gutters soak the lower edge of the deck and the fascia.
How roofers check it
From the attic, look for dark stains, daylight at nail holes, sagging between rafters and moldy spots. From the roof, soft spots underfoot hint at rot. The full picture only comes at tear-off, when every sheet is exposed, which is why good replacement contracts state a per-sheet price for any decking found to be damaged.
Plywood vs OSB
Kept dry, both last indefinitely. Plywood tends to dry out and recover better after brief wetting, while OSB edges can swell permanently when soaked. Older Georgia homes often have plywood or plank sheathing, and many newer homes have OSB.
Old plank decking
Some older homes have 1x boards with gaps between them. Shingle manufacturers limit installation over wide gaps, so a replacement may require new sheathing over or in place of the planks.
Signs it is time
- A wavy roofline or dips between rafters.
- Nails backing out across one area.
- Black, flaking or crumbling wood seen from the attic.
See OSB vs plywood roof decking and roof ventilation basics.