The answer to 'why is my roof decking' is that there are several common causes for roof decking issues, including water damage, rot, and structural problems. The roof decking is the plywood or OSB material that forms the base for your roof shingles or other roofing materials. Issues with the decking can lead to leaks, sagging, or even complete failure of the roof.
Some common symptoms of roof decking problems include visible water stains, soft or spongy areas, and uneven or sagging sections of the roof. These issues are often caused by long-term exposure to moisture, which can lead to wood rot and deterioration of the decking material. Structural problems like loose or missing nails can also cause the decking to become unstable.