A deck drainage system includes a plurality of hanger clips. Each hanger clip may have a plurality of mounting holes configured to fasten the hanger clip to a support at selected elevations. A soffit may be mounted to the hanger clips without fasteners and located completely below the deck, such that not every hanger clip directly contacts the soffit. A slope of the soffit may be selected by mounting at least two of the hanger clips to the support at different vertical elevations. The soffit may be configured to slope beneath the deck and drain water therefrom in a selected direction.