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Flexible liner insulation

Insulating flues improves the draw.

When do we need to insulate a chimney liner?

  • When the chimney is exposed on an outside wall;
  • When the stack is particularly tall or;
  • When the flue is of a large diameter.

Insulated liners keep the flue gases warmer, increase the upward speed of those gases and help prevent condensation.

Otherwise, it is not necessary. The air between the liner and the flue will insulate the liner.

Installing with a chimney wrap

insulated chimney liner

Instead of feeding the flue down the chimney, you haul it up the chimney. The person at the top has to have a very secure platform (e.g. scaffolding). A cherry picker might work but add the liner and wrap weight to the maximum allowed by the cherry picker.

Vermiculite to insulate a flue liner

Vermiculite (Micafi) is supplied in bags. It is very light and will be taken by the wind easily.

Vermiculite cannot catch fire and is used to insulate chimney liners.

Isolate flue liner

It is poured into the top of the chimney and will cascade down the chimney onto the closure plate, filling the gap between the liner and the chimney itself all the way to the top.

Vermiculite is only suitable for chimneys with a few inches of air gap.

For more information visit our blog about insulating a flue