A herniated disk, sometimes (incorrectly) called a slipped disk, is a common cause of severe back pain and sciatica. A disk in the lumbar area becomes herniated when it ruptures or thins out, and degenerates to the point that the gel within the disk (the nucleus pulposus) pushes outward.
The ceiling fan's downrod must be long enough for the fan's blades to clear the ceiling. A fan with a 12-inch downrod works for a vaulted ceiling with a one-quarter-to one-third-inch pitch. An 18-inch downrod is sufficient for a pitch that is five-twelfths to one-half inch.
Take the popular Fanimation ceiling fan The Huxley for example, which dimensions indicate the blades will be 18.75 inches from the ceiling with the downrod that is included (6 inches). This would mean on a 9 foot ceiling the blades would be 7 feet 5.25 inches from the floor.Now, if you wanted to maintain that 7 foot 5.25 inch blade height, but were installing it on a 12 foot ceiling, you would require an extra 3 feet or a 42 inch extension downrod.Basically, you can use the following mathematical formula to determine the downrod length you need.ow, if you wanted to maintain that 7 foot 5.25 inch blade height, but were installing it on a 12 foot ceiling, you would require an extra 3 feet or a 42 inch extension downrod.