After investigating last week's house fire on Slabtown Road in Zionville, authorities believe an unsupervised space heater was the culprit. David Hancock with the Watauga County Fire Marshall's Office said the homeowner was out of town and had left a small space heater in his bathroom blowing on his pipes to keep them from freezing.  Hancock said a wastebasket was also in the general area and the heat from the heater is believed to have caught debris in the wastebasket on fire. Hancock explained the heater was positioned a good distance from the wastebasket, but not quite the recommended three feet. When asked what the homeowner should've done differently to prevent his pipes from freezing, Hancock said setting a thermostat at your home is the best option.  Hancock explained heat tape for pipes is also a good insulation option. The fire caused an estimated $20,000 - $30,000 in damages to the home.