Chances are if you need to ask yourself this question, a permit is probably required. The NJ Uniform Construction Code states, "A building or structure shall not be constructed, extended, repaired, removed or altered ......" without construction permits except for ordinary repairs.
The term "structure" as used above includes: sheds, decks, homes, factories, fences (over 6 ft.) signs, etc. The term "altered" includes roofing & re-roofing, siding, and in some cases, window replacement, the installation of fireplaces and heat stoves.