The answer to 'why is my roof decking clogged gutters' is that clogged gutters can cause water to back up and seep into the roof decking. This can lead to water damage, rot, and even structural issues with the roof. Clogged gutters prevent proper drainage and allow water to pool, which can then work its way into the roof system through the decking.
Some common causes of clogged gutters include leaves, twigs, pine needles, and other debris buildup. This debris can accumulate over time and block the flow of water through the gutters. If the gutters are not cleaned regularly, this debris can eventually work its way into the roof decking and cause problems.