How high must chimneys extend compared to any portion of a building within 10 feet?

Chimneys must extend at least 2 feet higher than any portion of a building that is within 10 feet of the chimney. This requirement is crucial for ensuring that the emissions from the chimney are adequately dispersed above the roofline, which helps to prevent the buildup of harmful gases in the vicinity of the building. If the chimney is not tall enough, smoke and other combustion byproducts can flow back into the structure or neighboring areas, posing health risks and reducing the effectiveness of the chimney's draft.

The 2-foot height requirement acts as a standard to help maintain air quality and safety in residential settings. It applies to all scenarios where a building feature such as a roof or adjacent structure is in close proximity to the chimney, ensuring that the chimney's height is sufficient for proper ventilation.