Short Answer
Decking is evaluated after the existing roofing is removed or where accessible. Signs of deterioration can include rot, delamination, soft areas, structural damage, and water damage.
Detailed Explanation
Roof decking can only be properly evaluated after the existing roofing is removed. During tear-off, the contractor inspects every section of the deck for signs of deterioration. Rot — wood that's soft, crumbling, or discolored from fungal growth. Delamination — plywood or OSB where the layers are separating. Soft areas — sections that flex or give when walked on, indicating loss of structural integrity. Water damage — dark stains, swelling, or warping from moisture exposure. Structural damage — cracks, splits, or missing sections. Any deteriorated decking should be replaced before the new roofing system is installed, because the new system depends on a solid substrate for proper fastening and performance.
Why It Matters
Installing a new roof over deteriorated decking compromises the entire system. Proper deck evaluation and replacement is essential for a roof that performs as intended.