We have come across many decks with trapped debris in between the boards. It is important to keep the airflow in between the board to inhibit dry rot and fungus.

Wood decks need to have enough spacing between the boards for adequate airflow to reduce incidence of trapped moisture. If the boards are too tight moisture will be trapped when the wood swells causing dry rot and fungus over time. Adequate spacing between the wood boards is 1/16 to ¼ inch and a good deck contractor will take this in consideration when constructing a deck. Boards clogged with dirt, leaves and other debris will retain moisture causing problems in the future.  The homeowner should keep the boards free of debris by simple cleaning and general deck maintenance in the spring and fall.   Use a putty knife or some other flat narrow tool to run in between the boards to loosen any debris.