Homes built on varying terrain have their own set of chimney and flue regulations.
Flue height above flat roof.
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.
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.
Flues need to be 600mm higher than the highest part of the roof within 3 metres.
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.
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.
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 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 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.
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.
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.
1 my flue length is 3 50 m single skinned and draws very well.
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 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.
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.
Degrees the height of flue or chimney stack will need to be at least 1800mm above the roof when not close to the ridge.
