How Far Should A Flu Be Installed Above A Roof

Minimum clearance from combustible material.

How far should a flu be installed above a roof. 450 mm 18 in. If the pipe is farther than 10 feet from the roof peak it must be 2 feet above the highest point of the roof within 10 feet. Extend the vent pipe at least. Place vent support straps along the pipe every 8 feet if it s more than 25 feet long.

For gas vents or a type l vent this distance above the roof surface must be at least 2 ft 0 61m. The minimum clearance may be reduced by 50 percent to 225 mm 9 in if suitable shielding is installed either on the pipe or on the combustible surface. Vent caps larger than 12 must be located at least 2 feet above the highest point and 2 feet higher than any portion of the building within a horizontal distance of 10 feet. The top of the chimney should be at least 3 ft 0 92 m above the roof surface.

If the flue exits the roof further down then it must extend high enough to acheive 2 3m of horizontal clearance. Next roofing underlayment often made of building paper or felt is installed as the first weatherproofing layer for a pitched roof. Install no more than two elbow pipes at 45 degree angles if running the pipe through a chimney stack. Keep flue pipe as straight as possible for horizontal runs.

A flue pipe must never pass through a combustible floor or ceiling or through an attic roof space closet or concealed space. This specification makes sure steep roof slopes are cleared. In other words the highest point within a 10 foot circle of the pipe. Match the vent pipe to the furnace maker s recommendations either sheet metal or vinyl.

Vertical blue line along the left side of the chimney in our photo.