The pilot reported that, prior to landing, she obtained weather conditions at the airport, which included calm wind and light rain. After calculating the landing performance, she determined that the destination airport was adequate, and continued the approach to landing. Upon touchdown, she realized that the runway was wetter than anticipated, and applied maximum braking efforts, which included the application of the emergency brake system. Despite the use of maximum braking, the airplane “failed to decelerate at the normal rate.” The pilot initiated a right turn to decelerate, however, the airplane exited the departure end of the runway and impacted approach lighting and the airport perimeter fence, which resulted in substantial damage to the left wing. The pilot reported that there were no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. The automated weather observation station located on the airport reported that, about 9 minutes before the accident, the wind was from 090° at 3 knots, 7 statute miles visibility and light rain.