Thread: Gas fireplace flue (chase) clearance above roof

Does anyone know if the clearance standards are the same for a natural gas fireplace flue (chase) as they are for a wood burning fireplace?

The metal flue I inspected extends 3 feet above the roof line however it sits within 10' of a second floor dormer which towers above the flue by at least 8 feet. Not sure if the same clearance requirements apply to this natural gas flue that being having to extend 2' above a structure which is located within 10' of the flue. Thanks.

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From Figure G2427.6.4 in the 2006 IRC:
Roof Slope -|- Minimum Height
Flat-6/12 -|- 1.0 feet
6/12-7/12 -|- 1.25 feet
7/12-8/12 -|- 1.5 feet
(and gets higher with steeper roof slopes)

However, the gas vent must be not less that 8 feet from a vertical wall or similar obstruction, or, if less than 8 feet from a vertical wall or similar obstruction, the vent needs to be at least 2 feet higher than the any portion of the building within 10 feet.

At less than 10 feet, but if greater than 8 feet, your gas vent should be okay.

- G2427.6.4 (503.6.4) Gas vent termination. A gas vent shall terminate in accordance with one of the following:
- - 1. Gas vents that are 12 inches (305 mm) or less in size and located not less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate above the roof in accordance with Figure G2427.6.4.
- - 2. Gas vents that are over 12 inches (305 mm) in size or are located less than 8 feet (2438 mm) from a vertical wall or similar obstruction shall terminate not less than 2 feet (610 mm) above the highest point where they pass through the roof and not less than 2 feet (610 mm) above any portion of a building within 10 feet (3048 mm) horizontally.
- - 3. As provided for direct-vent systems in Section G2427.2.1.
- - 4. As provided for appliances with integral vents in Section G2427.2.2.
- - 5. As provided for mechanical draft systems in Section G2427.3.3