R1003.15.1

Section R1003.15.1 is titled 'Option 1' and covers requirements for masonry chimneys. The minimum area of flues, dependent on the shape of the flue, relative to the size of the fireplace opening, and methods for determining the flue area is established. The purpose of this section is to assure that fireplaces exhaust to the exterior properly which prevents the building from catching fire and smoke from entering the building.

The model shows a fireplace and 4 different shapes of flues with the fireplace opening and area of each flue highlighted with an overlay. The round flue area is 1/12th the area of the fireplace opening, the square and rectangular less than a 2:1 ratio are 1/10th the area, and the rectangular more than a 2:1 ratio is 1/8th the area.