A chimney must extend how much above a roof?

A chimney must extend at least 36 inches above the roof in order to ensure proper venting of combustion gases and to prevent any potential downdrafts that could lead to backdrafting into the living spaces. This height helps maintain an adequate distance from the roofline and other obstacles that could impede the free flow of exhaust gases. Ensuring the chimney is elevated above the roofline is crucial for maintaining a proper draft, which is vital for the efficient operation of the heating appliance it serves. Moreover, this height requirement is often aligned with building codes and standards related to safety, ensuring that the chimney functions effectively while reducing the risk of flue gas accumulation near the roof structure.