Chimney lining with vermiculite

[Mr_T25]

when building a class 1 chimney to accommodate a stove, what is the purpose of using vermiculite if you have already built th inner skin of the chimney with that pumice type material made of volcanic rock (Dunbrik flue system)?

I understand we will still need a flue liner in the cavity but some installers are talking about encasing the metal flue liner with vermiculite.

 

[stem]

If it's on an outside wall, and you insulate it, it will warm more quickly and help the flue gasses rise, and keep them rising without interference from cooling gas trying to descend. Also, there will be less chance of condensation forming.

I remember one installer who never installed insulation, stating that he had a bad experience of it getting damp, and if you have any gaps in your chimney blockwork, it may escape.

Some regulations may apply also, but a HETAS installer will be able to give you a definitive answer.