Most of our chimney extensions will accommodate 8-10 foot and 12 foot ceilings. If your ceiling height falls outside this range, you may need a custom cut. We sell 12 inches, 24 inches, and 36 inches extensions for our range hoods. Some models include 6 inches extensions. We cut the chimneys in our warehouse; just fill in the text box on the product page with your custom dimensions, or give us a call at 877.901.5530.