Height of Chimney?


How high above the roof does my chimney have to be?

The following information is for the typical chimney installation.  Always check your local codes.

Table from Metal-Fab, Inc.

Roof Pitch Minimum Height for gas chimneys, B-vent

Flat to 7/12 (305 mm) 1.0 feet

Over 7/12 to 8/12 (451 mm) 1.5 feet

Over 8/12 to 9/12 (610 mm) 2.0 feet

Over 9/12 to 10/12 (762 mm) 2.5 feet

Over 10/12 to 11/12 (991 mm) 3.25 feet

Over 11/12 to 12/12 (1218 mm) 4.0 feet

Over 12/12 to 14/12 (1524 mm) 5.0 feet

Over 14/12 to 16/12 (1829 mm) 6.0 feet

Over 16/12 to 18/12 (2134 mm) 7.0 feet

Over 18/12 to 20/12 (2286 mm) 7.5 feet

Over 20/12 to 21/12 (2438 mm) 8.0 feet

Metal-Fab B-vent (gas vent) instructions

For oil, wood or coal chimneys the top of the chimney must be at least 3 feet above the highest point of contact with the roof and at least 2 feet above the highest roof surface or other obstruction within 10 feet horizontally from the top of the chimney.

For more detailed installation instructions visit:

Metal-Fab Temp/Guard all-fuel chimneys

Metal-Fab L-vent for oil chimneys

We stock Metal-Fab B-vent for gas and Metal-Fab Temp/Guard for oil, coal and wood.  Temp/Guard is rated for 2100F intermittent and 1000F continuous temperatures.


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