The answer to 'why is my deck drainage problems' is that there are several common causes, including improper deck construction, clogged drainage channels, and inadequate slope or grading. Symptoms may include standing water, mold and mildew growth, and damage to the deck structure.
To address deck drainage issues, start by inspecting the deck to identify the root cause. Check for proper slope and ensure drainage channels are clear of debris. You may need to adjust the grading or install additional drainage features like downspouts or catch basins. For more complex problems, it's best to consult a professional landscaper or deck contractor who can evaluate the situation and recommend the appropriate solution.