The pilot reported that after landing on runway 11, "I realized that (runway) 5-23 was being used as a taxiway." He back taxied on runway 23, with the intent of departing runway 5. He made several CTAF transmissions to an airplane that had begun to taxi toward him on runway 23. Not knowing the taxiing airplane's intentions, he maneuvered his airplane to the left side of runway 5 and the left wing struck a construction sign.

The airplane sustained substantial damage to left wing and aileron.

According to airport NOTAM 09/076, runway 5/23 closed except to taxi Monday-Friday.

The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation.