If you have a building without a chimney then a twin wall insulated chimney with a stove could be the answer for you. Points to consider when designing this type of system include the following.

  • The product that we use will give a maximum of 3 meters of unsupported chimney for a 6 inch flue bore, something that could be important if like this customer you have a single storey building. The minimum recommended length of flue under building regulations is 4.5 meters and without this product it would not be possible to achieve the required length of flue. A large number of products will only go to 2 meters of unsupported length. 

  • It is very important when considering this as an option that the roof structure is considered and any floors that have to be gone through, the minimum air gap between the outside of the flue surface and any combustible is 50 mm.The outside of a 6 inch flue is usually 8 inch diameter so you need at least 12 inches in the correct location for the chimney run.

  • When the chimney passes through a floor, firestop components must be used and ventilated ceiling supports.

  • The need for lateral support along the length of the flue must be considered.

  • The structure of the wall behind the stove needs to be totally none combustible and dry lining will present a problem, it will have to be removed unless the distance behind the stove is considerable.

  • Only 1 offset in the chimney run is allowed excluding the connection to the stove and the offset must not exceed 20 % of the total vertical chimney. 

  • When the chimney passes through an attic or storage area it must be enclosed.

  • The position of the chimney termination need also to be checked it must not be too close to velux windows or the roof.

  • To avoid cooling of the gases the maximum length of the single wall flue pipe should not exceed 1.8 meters and in the case of the chimney opposite it was kept as short as possible due to the short overall length chimney height.

  • No connections are allowed to be concealed in roof voids, all connections must be available for inspection.


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Telephone : 029 20577739
Mobile : 0789 4904659
Email : familylowe@talktalk.net

Philip Lowe Cardiff Chimney Sweep t/a Fire and Flue Cardiff.