Pizza Oven Flue Extension Kit 140mm Matt Black

Please note you are purchasing a full set. This set can be returned but individual parts/items from the set CANNOT be returned. We do not except returns and offer refunds for parts/items that are part of this set.

Pizza Oven Flue Extension Installation Guide

We’ve worked closely with pizza oven manufacturers, architects, and customers to develop the safest and most effective method for extending your flue through a garden structure. This guide walks you through the process using our twin wall flue kits.

Each standard flue extension kit come with:

• Twin wall adapter
• Rain Cap
• Storm collar
• Locking bands 
• Fire cement

You can choose your required flue lengths and any additional components using the drop-down menu when ordering.

Before You Start

Our kits are designed to connect to your original single skin flue that came with the oven. If you’re replacing the single skin flue entirely, contact us first—sizing will change.

• Twin wall components allow safe extension through roofs with minimal clearance to combustibles.
• Avoid using single skin flue through a roof—it’s not recommended for safety reasons.
• Extending "out then up" is generally not feasible due to low roofs and oven placement—straight up through the roof is easier and cheaper.

Step 1: Determine Your Flue Size

Remove the rain cap from the flue and measure the internal diameter of the flue pipe. Common flue sizes:

• 100mm
• 125mm
• 130mm
• 140mm
• 150mm

Step 2: Measure the Height of the Extension Needed

Available flue extension lengths:

• 500mm
• 800mm
• 1000mm

These can be used alone or combined as needed.
Recommendation: Have at least 500mm protruding through the roof to allow space for flashing, storm collar, and rain cap.

Do you need an Offset?

If your plumb line does not fall directly over the centre of the pizza oven’s flue outlet, you will need to install an offset in the flue system. This allows you to align the flue with the exit point in the roof without repositioning the oven. 

To determine the required offset, measure the horizontal distance from the center of the pizza oven flue to the point where your plumb line lands.

Step 3: Choose Your Flashing Based on Roof Type

Flashing Options:

• Dektite Premium Black EPDM: Ideal for felt, metal, rubber, and wooden roofs. Fully rubber boot secured with silicone sealant and self-tapping screws (not included).
• Seldek Aluminium Black EPDM: For tile or slate roofs. Traditional aluminum/rubber boot.

Both flashings are suitable for 0–45° pitched roofs.

Optional: Add a Roof Support

A roof support can be attached to the underside of the roof between joists to help secure the flue and prevent movement.

Step 4: Prepare the Roof Opening

Determine the hole size based on your flue diameter:

• 100mm, 125mm, 130mm - Hole Diameter: 330mm
• 140mm, 150mm - Hole Diameter: 350mm

Step 5: Begin Installation

• Attach the roof support between joists.
• Insert the adapter into your single skin flue 
• Use fireproof rope or fire cement (provided) for a snug fit if needed.
• Assemble the twin wall flue sections by pushing them together and securing with the provided locking band.
• Drop the flue lengths from the roof down into the adapter.

Step 6: Install Flashing

Carefully cut a hole in the flashing based on your flue size:

• 100mm, 125mm, 130mm - Flashing Hole Diameter: 190mm
• 140mm, 150mm - Flashing Hole Diameter: 210mm

Use sharp scissors (not a Stanley knife) for a clean cut. Position the flashing around the flue and secure it to the roof.

Step 7: Final Assembly

• Slide the storm collar down the flue to sit just above the flashing.
• Apply a bead of silicone where it meets the flue for a watertight seal.
• Attach the rain cap and secure it with the included locking band.

✅ Installation Complete! Your flue is now safely and securely extended through your garden structure. Enjoy safe and efficient operation of your pizza oven!