Final answer:
The top of the flue on a pitched roof must be at least 2 feet above any roof part within 10 feet of the chimney.
Step-by-step explanation:
On a pitched roof, the top of the flue should be at least 2 feet above any portion of the roof that is within 10 feet from the chimney. This regulation is in place to ensure proper draft and to prevent fire hazards.
The flue height is also important to avoid downdrafts which can cause smoke to enter the building instead of exiting through the chimney. Flue design may incorporate a T-shape, which can assist in drawing up gases more efficiently.
This is related to Bernoulli's principle, where the crosspiece of the T-shape creates a pressure differential when there is a breeze, aiding in the upward movement of gases. However, while this design helps, it does not replace the need to adhere to the minimum flue height requirements.