(1) A person is guilty of arson in the third degree if he wantonly causes destruction or damage to a building of his own or of another by intentionally starting a fire or causing an explosion.
(2) In any prosecution under this section, it is a defense that no person other than the defendant had a possessory or proprietary interest in the building, or, if other persons had such an interest, all of them consented to defendant's conduct.
(3) Arson in the third degree is a Class D felony.