The height of the chimney above the roof surface measured at the up slope side of the chimney from the roof surface to the chimney top should be at least three feet the green line in our photo.
Fireplace vent pipe clearance.
In direct vent applications this clearance distance must be in compliance with local building codes the requirements of the fuel gas supplier for the heating appliance in use and the appliance manufacturer s instructions.
Gas fireplace direct vent termination cap clearance distances clearances between the gas fireplace exhaust vent and other building components or features.
For non direct vent applications that is side wall venting only the required clearance is 7 feet.
Most of the double wall stove pipe allows for 6 clearance from wall combustibles and 8 from ceiling combustibles.
This is a bit of an odd measurement and chimney clearance case because the chimney side is actually about 8 away from the roof edge.
Clearances for direct vent pipe may vary and these clearances will be specified by the manufacturer of your direct vent appliance.
See fire clearances single wall metal flues vents for the clearance from combustibles required for flue vent connectors these are not chimneys but rather the flue pipe smoke pipe or stack pipe that connects a heating appliance to a chimney.
This article gives typical clearance distance requirements between the termination cap of a gas fireplace or fireplace insert and other building or site features such as windows doors other mechanical system components air intakes exhausts.