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.

For gas vents or a type l vent this distance above the roof surface must be at least 2 ft 0 61m. Match the vent pipe to the furnace maker s recommendations either sheet metal or vinyl. 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. A flue pipe must never pass through a combustible floor or ceiling or through an attic roof space closet or concealed space.

Install no more than two elbow pipes at 45 degree angles if running the pipe through a chimney stack. 450 mm 18 in. This specification makes sure steep roof slopes are cleared. Next roofing underlayment often made of building paper or felt is installed as the first weatherproofing layer for a pitched roof.

Place vent support straps along the pipe every 8 feet if it s more than 25 feet long. Set the collar with the wide flange at the bottom on the surface of the roof. 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. When installing a new twinwall flue system if the flue exits the roof within 600mm horizontally from the ridge high point of the roof then the flue must extend a minimum of 600mm above the ridge.

If the flue exits the roof further down then it must extend high enough to acheive 2 3m of horizontal clearance. Extend the vent pipe at least. Vertical blue line along the left side of the chimney in our photo. Keep flue pipe as straight as possible for horizontal runs.

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.