R1003.9.3

Section R1003.9.3 is titled 'Rain caps' and covers requirements for masonry chimneys. The requirement for a rain cap to have a minimum area under the cap relative to the size of the flue is established. The purpose of this section is to prevent insufficient draft and smoke from entering the building.

The model shows a partial section of a flue with a rain cap and translucent overlays demonstrating that the area under the rain cap (to the outside air) has at least 4 times the area of the flue.