R1003.6

Section R1003.6 is titled 'Changes in dimension' and covers requirements for masonry chimneys. The disallowance of a change in size of the chimney wall or flue lining inside of or within a certain vertical distance of a floor, ceiling, or roof assembly it passes through is established. The purpose of this section is to prevent the building from catching fire, structural failure, and fireblocking from becoming compromised.

The model shows a section of a floor and chimney liner which is highlighted for the distances above and below the floor that it is not allowed to change in dimension or shape.