We have been working closely with Pizza Oven manufacturers, architects & customers to find the best solution for safely extending your pizza oven flue through a garden structure.
Our kits are based on you using your original single skin flue that has been supplied with your oven, if you are looking to replace this as well please get in contact as the sizing will change if this is removed.
All of our kits are made up of twin wall components, this means you can safely extend through a roof with minimal clearance to combustibles. (we do not recommend using single skin flue through a roof) We do get asked if you can extend out then up to avoid cutting a hole in the roof, this can sometimes be done but in the vast majority of cases the roofs are too low and the oven is located too far from the wall to make it possible, it is easier and cheaper to go straight up through the roof.
The first thing you need to do is determine the flue size of the oven, this can be done by removing the rain cap and measuring the internal diameter of the flue pipe, typically you will have a 100mm, 125mm, 130mm, 140mm or a 150mm flue.
Next you will need to know the height of the extension, in our kits we have 3 flue sizes; 500mm, 800mm & 1000mm and these can be used together or on their own depending on your requirements. We would recommend having at least 500mm protruding through the roof to cater for the flashing, storm collar and rain cap.
Now you will need to choose your flashing and this will depend on your roof covering.
The first option we have is a full rubber boot and this is suitable for Felt, metal, rubber and wooden roofs, it is designed to be stuck directly to the surface of the roof with a silicone sealant and self-tapping screws (not included). Dektite Premium Black EPDM.
The second option is the aluminium / rubber boot and it designed for use with tile or slate roofs and dressed in the traditional way. Please note these 2 flashings can accommodate 0 – 45 degrees pitched roofs. Seldek Aluminium Black EPDM.
An optional roof support can be added to the kit, this can be attached to the underside of the roof and secured between the joists and this will stop any movement in the flue and make sure everything is secure.
• Once you have determined the location of your oven, you will need to make a hole in the roof, the size of the hole depends on the diameter of the flue, the sizes below will give you a safe distance to combustibles;
• 100mm, 125mm & 130mm you will need to make a hole in roof 330mm in diameter;
• 140mm & 150mm you will need a hole 350mm in diameter;
• Once your hole has been made and your oven is in the correct position it is time to start the build;
• Firstly attach the roof support to the underside of the roof between the joists ready for the twin wall to be inserted;
• Please locate the adapter (for 140mm flue you will have 2 adapters) and insert into the existing flue, if the adapter is loose in the flue you can use the fire proof rope or fire cement provided to get a good seal;
• Then you will need to fit the length/lengths, these push together and are secured using the provided locking band, please note there is no need to use any sealant or fire cement on the joints of the twin wall. The easiest way to install in to drop the lengths from the roof through the roof support and attach to the adapter with the locking band provided;
• Now you should have at least 500mm of twin wall sticking through the roof;
• Next you will need to cut the correct hole in the flashing, please see below sizes. This needs to be done very carefully with a sharp pair of scissors rather than a Stanley knife;
• 100mm, 125mm & 130mm you will need to make the flashing 190mm;
• 140mm & 150mm you will need the flashing 210mm;
• Now the flashing in in place it is time to fit your storm collar, this slides down the flue and sits just above the flashing. It is also worth putting a bead of silicone where the collar meets the flue;
• The final step is to attach the rain cap and secure with the included locking band.
Dimensions / Specifications
5" insulated adapter:
5" storm collar:
5" rain cap:
500g vitcas fire cement: