Flue Height Above Roof

Homes built on varying terrain have their own set of chimney and flue regulations.

Flue height above roof.

If the flue is over 3 m from the roof apex the flue top must be 1 000 mm minimum above the roof and at least 3 m horizontally from. Flues need to be 600mm higher than the highest part of the roof within 3 metres. 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. If the pitch of the roof is 38 degrees or greater the termination point of the flue or chimney will need to be 2300mm horizontally from the roof line and roofing material.

Additionally per our rule we need to add 2 feet or 24 inches giving us a total height of 64 inches. The flue termination is within 600mm horizontally of the ridge in which case the flue finish at least 600mm above the ridge. If unsure please give us a call. The distance between the cowl of the flue and the adjacent roof wall structure should be higher than 2 3 mtr.

The minimum height of the top of the flue varies depending on where it is on the roof. Back to our example over a run of 10 feet the roof would rise 40 inches. Degrees the height of flue or chimney stack will need to be at least 1800mm above the roof when not close to the ridge. The grey area in the picture shows where the flue must not terminate on a roof with standard non flammable roof.

The picture below may illustrate it better than my words. So take the top number of your roof pitch and multiply it by 10 then add 24 note example 1. 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. That height will be determined by the pitch angle of your roof.

Roof pitch rise run in inchesminimum height flat to 7 12 1 0 foot above the roof surface 7 12 to 8 12 1 5 feet above the roof surface 8 12 to 9 12 2 0 feet above the roof surface. Flues that are more than 3 metres away from the highest part of the roof need to be 1000mm above the flue penetration. The minimum chimney height recommended for minimum performance of wood burning and multi fuel appliances is 4 5 m from the top of the appliance to the top of the chimney. Vent caps 12 and smaller may terminate a distance above the roof if 8 feet or more away from a vertical surface as follows.

Flue outlet height unsafe areas diagram. As illustrated below if your flue exits through the roof within section a then you are required to rise at least 1800mm vertically above the roof surface and at least 600mm above the ridge. If the flue is within 3 m horizontally of the roof apex the flue top must be at least 600 mm above the roof apex. Felted roofs the flue must terminate a minimum of 1 8m above the combustible surface.

Do i need extra room ventilation.