R1003.12

Section R1003.12 is titled 'Clay flue lining (installation)' and covers requirements for masonry chimneys. The requirement for clay flue linings to be installed in accordance with a standard, started and ended at specific points, limited in slope from vertical, laid in specific mortar which conforms to a standard, provided with smooth joints on the inside, provided with an airspace between the liner and the chimney which does not exceed the thickness of the liner, and supported on all sides is established. The purpose of this section is to prevent the building from catching fire and structural failure of the chimney.

The model shows a section of a chimney with clay flue liner sections being joined. The excess mortar squeezed out of the joint is removed from the interior and exterior, and translucent overlays at the bottom demonstrate that the space between the faces of the liner and the chimney wall does not exceed the thickness of the liner.