Flue liner insulation

Leca is a type of insulation, a little like light pebbles that you pour around the liner. It is good for smaller chimneys - for very large chimneys Linertherm is a better choice.

Linertherm is an insulation for flexible flue liners that you simply wrap and strap around the liner. The advantage is it is quick to put on and easy to install - allowing for some flexing of the liner around bends in the chimney.