Height on the roof
When installing a new twinwall flue system, if the flue exits the roof within 60 cm (horizontally) from the ridge (high point) of the roof then the flue must extend a minimum of 60 cm above the ridge.
If the flue exits the roof further down then it must extend high enough to acheive 2.3m of horizontal clearance. That height will be determined by the pitch (angle) of your roof. We can work out the height required when we design your system. If unsure please give us a call.
For buildings with combustible roofs e.g. felted roofs, the flue must terminate a minimum of 1.8m above the combustible surface: