Replacing stained or rotten roof decking is a part of the roofing process. Most often, your need to install a new roof means the existing system has expired. Throughout previous or active leaks, water may have created bad roof decking.
Bad decking is most often an unforeseen by the roofer during the estimate process. While we may see more obvious wood rot, smaller areas may only be found once the old roof is stripped away. Many times we may even include a sheet or two in the proposal if we know there is a need to replace.
Fortunately replacing only a few sheets (a standard sheet is 4′x8′) does not cost the owners a ton of money. Make sure that you ask or find the costs associated with additional wood work costs. This normally is on the proposal somewhere and usually priced by the square or lineal foot. Remember that there are 32 square feet in one sheet of plywood.
Less Obvious Bad Roof Decking
Some areas of wood decay/rot are simply not visible from walking the roof.
Obvious Signs of Rotted Roof Decking
Current or previous leaks are a good indicator of the need for some roof deck repairs. The roof has probably been leaking for a while once a leak actually shows up inside. Areas such as overhangs or additions may have wood rot you can see from walking around the home.