That will suffice on a roof with rafters set 16 inches apart with minimal roof loads.
Roof change plywood.
Hammer down any large nails that are exposed by the removal.
Install a layer of roofing insulation as recommended by the roofing manufacturer.
Place a new plywood board in the same location ensuring the ends align over roof rafters.
Inspect the underlying roof sheathing for damage and make any needed repairs.
Loads will vary with the pitch of the roof.
Rotted plywood cannot support the weight of a roof the way healthy wood can nor can it safely grip the nails put into the roof and keep them held firm.
Most roofs will be sheathed in plywood at least 3 8 inch thick.
Step 6 unroll new roofing felt over the new plywood and extend it at least 3 inches over each edge of the new plywood.
Rotted plywood can cause a number of issues.
A half inch cdx plywood is often used with rafter with 24 inch spacing.
This is a popular option because it presents homeowners with functional but affordable roof sheathing.
Moisture causes wood to rot and rotten wood absorbs water even more readily than fresh wood.