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Installing twin wall flue through the house

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Installation twin wall flue through the house

 An internal flue system is kept warmer than an external one and therefore keeps the flue gases hotter, resulting in better draw and less tar deposits. It is cheaper, quicker and easier to install an internal twin wall flue system than an external system.

If the flue passes through bedrooms it should be “boxed in” with an inspection hatch situated in a specific place. In the loft, it will likely need some type of mesh protection.

A bedroom or a storage space is a great example where toys or curtains may easily get too close from the flue/chimney. In this situation, guarding is more commonly done by boxing the flue in, although some type of mesh is still a way to do it. We recommend solid boxing in because, it means that nothing can accidentally fall into the void. You also need consider the fact that, there is ventilation where the twin wall passes through the floor.

Floor passage - wooden floor

The passage through the floor can be done with:

- a Ventilated Firestop plate against the ceiling (in practice customers often take a round trim plate); and
- a Vented Floor support on the floor. 

1. Put a length through a pre-prepared wood box in the floor and slide down the Vented Floor support plate.

2. Screw this Floor support plate to the box. Next, screw the support clamp directly to the jacket pipe of the length. 

3 Glue the Ventilated Fire Stop plate (or round trim plate) onto the ceiling .

flue through ceiling 



Safety distances

The minimum distance between the insulated chimney's outer wall and the combustible materials is 60mm (G60).

The minimum distance between the single wall stove pipes and the wooden floor is 3 times the diameter (of the pipe) and never less than 375mm. For 5" pipes (125mm) this means always minimum 375mm. For 6" pipes (150mm) it is 450mm.

If the flue passes through a first floor, it must be boxed in.

vented flue

Flue Passage through the roof

Where the flue goes through the roof a flashing keeps everything watertight. The roof penetration is usually the part that customers are most concerned about, however it is not a difficult job and it is easy to make a weatherproof seal around the flue and roof using one of our ranges of flashing.



 FLue through roof



Twin wall flue pipe