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Flue and Chimney Design Service - Extension insulated flue

Flue and Chimney Design Service

Installing a stove in an extension is relatively easy but there are a few things to consider.

If you want to run the flue out through the wall of your extension then - do not use this form. If you are running the flue out through the wall of the extension then as long as the flue will be at least 2300mm from the main house then use our external flue system form.

If you are making a false inglenook then let us know in the notes section of the application form.

A flue system for an extension takes two general forms:

Within 2300mm of the main house (or other building)

Here the flue has to run up the side of the house and above the roof. You will probably need to add an offset to the flue to bring it 50mm from the wall of the house.
This is a relatively expensive way of making a flue system and if you can run the flue further than 2300mm from the main house then this will definitely be cheaper.

Further than 2300mm from the main house (or other building)

Here the flue system is treated as for a normal installation in a house - straight up and through the roof.

For our flue designers to design your internal flue system using insulated twin wall flue pipe we will need a few details and measurements from you. The big link below will take you to our application form where you can enter these details.

It takes a little bit of time to gather the measurements and details that we need and to help out we have made a printable checklist of all the details needed - you simply print this list out and then fill in the spaces as you go.

Click here for the application form

Some decisions you will have to make about your flue system

Single skin flue pipe - you can run the first section of flue from the stove using single skin flue pipe. Most stove manufacturers recommendation is not to use more than one metre of single skin before going into twin wall insulated flue pipe. You have to change from single to double before the flue reaches the ceiling. So, on the one hand, single skin flue is cheaper than double skin, but on the down side it does mean that you have two different types of flue (with different external diameters) within the room.

Type of single skin flue pipe - you can choose black enamel flue or stainless steel flue. The stainless steel flue pipe lasts longer than enamel flue, fits better with double skin adaptors and can be sprayed to match the stove.


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