What is the cost of replacing roof decking?
Short answer. Replacing a few damaged sheets during a reroof adds a modest amount, but replacing all the decking on a roof is a major added cost, because every 32 square feet of roof takes another sheet plus the labor to remove and install it. A typical 25 square roof needs roughly 80 sheets for a full redeck, which is why the per-sheet price in your contract matters.
Spot repairs vs a full redeck
Most reroofs need only scattered sheets replaced: soft spots at the eaves, around chimneys and pipes, or where an old leak sat. A full redeck is a different job that replaces the entire roof surface below the shingles.
When a full redeck is needed
- Spaced plank sheathing. Older homes that once had wood shakes often have boards with gaps between them. Asphalt shingles must be installed on solid sheathing, so these roofs typically need new decking.
- Widespread rot or delamination from years of leaks or poor attic ventilation.
- Sagging or undersized decking that cannot hold nails or bends between rafters.
- Fire or major storm damage.
What drives the cost
- Sheet count. Roof area divided by 32, plus waste. A 2,500 square foot roof is about 78 sheets before waste.
- Material. OSB is usually cheaper than plywood; thicker panels cost more.
- The lumber market, which moves panel prices up and down.
- Labor and disposal for removing the old boards.
- Hidden framing repairs once the deck is open.
Insurance and code
If a covered storm claim leads to a replacement and code requires solid decking, ordinance or law coverage in your policy may help pay for it. See code upgrades and ordinance or law coverage, plus OSB vs plywood roof decking and roof replacement cost in Georgia.