Table of rooftop chimney clearances for metal b vent chimneys flues.
Boiler vent heighy over roof.
This is because the waste generated by combustion can include dangerous gasses like carbon monoxide so you don t want that waste gas too close to an opening.
Above the roof surface with a listed cap or listed roof assembly.
A category i vent system works by allowing heated flue products to rise vertically so the vent pipe must rise vertically from the boiler vent connection as soon as possible.
Gas vents 12 inches 305 mm in size or smaller with listed caps shall be permitted to be terminated in accordance with figure g2427 6 5 provided that such vents are at least 8 feet 2438 mm from a vertical wall or similar obstruction.
300 mm below above or alongside an opening window air vent or other ventilation opening 75 mm below guttering drain pipes or soil pipes 200 mm below eaves roof overhang 300 mm above ground roof or balcony level 2000 mm below a velux window for a vertical flue 300 mm above roof pitch or flat roof for a vertical flue.
You see if you ve got a boiler in your attic and the flue goes through the roof there s a chance it could get bashed or pulled on accidentally when you re up there.
2 5 feet above the roof surface.
In all areas exhaust vents should be at least 1 foot above roof surface.
2 0 feet above the roof surface.
All horizontal runs of vent pipe must rise 1 4 inch per foot of run to maintain proper draft in the vent.
Now for the math lesson.
Exhaust vents must be protected against rain and equipped with back flow prevention features e g flap dampers.
1 0 foot above the roof surface 1 7 12 to 8 12.
1 5 feet above the roof surface.
Minimum height above the roof surface 1 flat to 7 12.
Exhaust vents must not be located where they might be obstructed by drifting snow consult local experience as to the height of snow drifts against buildings.
Depending on the size of the boiler the flue must be positioned a certain distance from the nearest window door or air brick typically this is around 30 60cm if it s to the side or above the opening and a bit more if it s below.
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.
You should also limit the length of the horizontal flue pipe.
Securing any joints with brackets will help to ensure your flue can withstand people banging a suitcase or accidentally knocking it without wobbling or coming loose.