Flue Kit for Extension

There are two ways to build your flue:

Only twin wall flue pipes

- No dangerous hot pipes in the room.

- Esthetically more pleasant.

- Better draw.

Single wall and twin wall pipes

- A single wall flue radiates warmth into the room ( this does reduce the draw somewhat as well).

- These stove pipes can be used up till 450mm under a flammable roof (150mm for a non combustable roof).

- Single wall pipes should stay 450mm from flammable walls and other flammable materials (unless sheilded like on the picture).

For a flue in an extension, the height of the flue depends on its distance from the wall and nearby structures. Here are the key points to consider:

1. If the flue is within 2.3 meters of the wall or any nearby structure:

   • The flue must terminate at least 1 meter above the roofline or any opening (like a window or door) within that 2.3-meter radius.

2. If the flue is more than 2.3 meters from the wall or nearby structures:

   • The flue can go straight up, but it should ideally be a minimum of 4.5 meters in total height to ensure proper draught and functionality (in practice 3 meters may be enough)

3. Flat Roofs:

   • If the extension has a flat roof (pitch less than 10°), the flue must terminate at least 1.8 meters above the roof surface if the roof is combustible.

This distance determines what wall support to use.

Normally the cheapest solution is to take a wall support 50 -75mm. However in case of an overhanging roof, you may want to use another wall support

When the distance is more than 350 mm, there is no wall support for this. If the height above the roof is more than 1.5m; you need a Roof Stabiliser Bracket to support the flue. In practice, this will only work for a flue with a distance from the wall of more than 1.5m (if it is less, the flue needs to end above the gutter; you can not stabilize that with a roof stabilizer bracket)

The choice of the flashing depends upon:

- What kind of material material is covering the roof, and

- The pitch of the roof (0° being a flat roof, 60° a sharp roof)

Automatically we add a roof support and -when required- a storm collar.

There are 2 types of cap to choose from:

Rain cap
Will keep vertical falling rain out of the flue. In case of side winds, rain will enter the flue. In case of a flue outside this is less of a problem, as it will not floote into the house. 

All weather Cowl
Keeps rain out of the flue. Also blocks downwinds from entering your flue. Downwinds come from higher objects in the vicinity (up to 10mtr), and without this Cowl they will blow the smoke back into your house.