Chimney pots or tops are set in a bed of mortar on the masonry chimney cap. The base of the chimney pot need not match the dimensions of the flue liner it is being installed on top of, but should not impinge on the inside area of the flue liner except for the maximum 3/4 of an inch in the corners. The flue liner may extend up inside the chimney pot, or the flue liner may be flush with the top surface of the chimney cap. Additional anchoring may be used to prevent damage from tornadoes, hurricanes or earthquakes. A 1/4 – ½-inch diameter hole may be drilled in at least two opposite sides of the chimney pot and a bar used to anchor it into the grout or the chimney walls.
When installing chimney pots on wood chase chimneys, special attention should be given to preventing water leakage around the base of the chimney pot.