For instance on our flat roof example with a 500mm roof cavity the flue length for this section would be 500mm.
Flue height above flat roof.
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.
The distance between the cowl of the flue and the adjacent roof wall structure should be higher than 2 3 mtr.
Pitched roof second story ceiling cavities attics if your roof is pitched you have an attic or a second story above it is best to measure the height from ceiling penetration to roof penetration including any other cavities or spaces the flue needs to travel through to reach roof.
This means that below 38 degree roof pitches that the height of the flue outlet should be at least 1800mm above the roof when not close to the ridge and above 38 degree roof pitches the flue outlet height should be 2300mm horizontally back to the roof flue height figures are given in the table above where the flue is not close to the ridge.
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.
Vent caps 12 and smaller may terminate a distance above the roof if 8 feet or more away from a vertical surface as follows.
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.
1 flue length min 4 20 m 2 outlet min 40 cm above ridge line if more than 8 m away from higher points on surrounding buildings otherwise 40 cm above that height.
The minimum height of the top of the flue varies depending on where it is on the roof.
If your boiler flue has to face out onto a public space the installer will have to ensure that it s fitted at least 2 1 metres above ground level over head height.
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.
2 outlet is 40 cm above ridge and is fine although it is only 6 m away from the wall of a higher building.
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.
1 my flue length is 3 50 m single skinned and draws very well.
Homes built on varying terrain have their own set of chimney and flue regulations.
Flues that are more than 3 metres away from the highest part of the roof need to be 1000mm above the flue penetration.
Vertical flues the majority of boiler flues exit out of a wall horizontally but if the flue from your boiler comes out at roof level then there are also some regulations that need to be considered.
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.
