The Self Build Self Help Site Building a chimney
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photo of chimney flue in preparation

Vermiculite is a very lightweight, high temperature insulant. It is mixed with cement in a ratio of 6:1 to fill the void between the flue liners and walls. Use very little water to make the cement mix. Alternately, use Perlite - 10:1 with cement

photo of chimney flue in preparation

The liners are built up - but don't build up too many before filling the cavity with Vermiculite cement.

photo of chimney flue in preparation

Eventually the structure emerges from the roof line.








The photos below show the start of a flue formed from concrete liners. These are larger than clay liners and are square in section.

photo of chimney flue in preparation

The first concrete liner is bedded onto concrete lintels that are spanning the chimney breast.

photo of chimney flue in preparation

In this build the liners were not surrounded by vermiculite cement - no need.

photo of chimney flue in preparation

The concrete liners are stacked one upon another. The end result is the same - a gas tight flue.