Slatted wood decks and walkways (such as a handicap ramp) will not count as impervious surfaces. If, on the other hand, a deck is enclosed to produce a screened porch or sunroom, the roof usually means it now results in being impervious and should be counted to any highest allowance. http://bookmarkstime.com/story8624603/the-best-side-of-huntersville-nc-deck-stain