Table 803.2(1) through
Table 803.2(5) shall be used for chimneys and vents not
exposed to the outdoors below the roof line. A Type B
vent or listed chimney lining system passing through an
unused masonry chimney flue shall not be considered to
be exposed to the outdoors. A Type B vent passing
through an unventilated enclosure or chase insulated to a
value of not less than R-8 shall not be considered to be
exposed to the outdoors. Where vents extend outdoors
above the roof more than 5 feet (1524 mm) higher than
required by Table 802.6.2, and where vents terminate in
accordance with Section 802.6.2(1), the outdoor portion
of the vent shall be enclosed as required by this section
for vents not considered to be exposed to the outdoors or
such venting system shall be engineered. Table 803.2(6)
through Table 803.2(9) shall be used for clay-tile-lined
exterior masonry chimneys, provided the following
conditions are met:
- The vent connector is Type B double-wall.
- Not less than one appliance is draft hood-equipped.
- The combined appliance input rating is less than the maximum capacity given by Table 803.2(6) (for NAT+NAT) or Table 803.2(8) (for FAN+NAT).
- The input rating of each space-heating appliance exceeds the minimum input rating given by Table 803.2(7) (for NAT+NAT) or Table 803.2(9) (for FAN+NAT).
- The vent connector sizing is in accordance with Table 803.2(3). [NFPA 54:13.2.22]