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. It is best practice to position the chimney, so that it goes straight up as near to the roof ridge as possible. The first diagram is the measurements directly correlating the roof's pitch to the height of the flue and the distance form the roof. The second is a image showing how the standard and common pre fabricated flue system is placed, fixed and supported through the roof and loft.