The answer to 'what causes roof decking' is that roof decking, also known as roof sheathing, is the structural base that supports the roof's outer layer or roofing material. Roof decking is typically made of plywood, oriented strand board (OSB), or solid wood boards. The most common causes of issues with roof decking include water damage, rot, and structural issues.
Roof decking can become damaged over time due to exposure to the elements, such as rain, snow, and UV radiation from the sun. This can lead to the decking becoming warped, cracked, or weakened, which can compromise the structural integrity of the roof. Improper installation or poor ventilation can also contribute to issues with the roof decking.