Squirrels in a Chimney or Flue

How it happens

Down, Not In

A squirrel in a loft chose to be there. A squirrel in a chimney usually did not.

An open, uncapped pot is an attractive-looking cavity from above, and an animal that puts its head in and slips can end up several metres down a flue it cannot climb. Modern flues are the worst for this: a smooth liner gives nothing to grip, whereas an old brick or parged flue at least offers purchase.

The other version is deliberate — a disused flue used as a nest site, with material dragged in from above. That is less urgent but it is a genuine blockage and it does not clear itself.

You can usually tell them apart by the sound. Frantic scrabbling in one place, sometimes for hours, is an animal that is stuck. Intermittent movement and material falling is a nest.

Photographs on this page are for illustration purposes only.

Do not light the fire

The First Rule

People do try this, and the reasoning is understandable: smoke it out. It does not work and it produces the worst possible result.

An animal part-way down a flue is usually below the point where it can escape upward and unable to climb. Lighting a fire kills it slowly, in your chimney, where you cannot reach it. You then have a decomposing animal in a flue, a smell through the room for weeks, and a blockage that still has to be removed.

The same applies to anything poured, sprayed or dropped down. Leave the flue alone.

The gas warning

This Part Is Not About the Animal

If a squirrel or its nesting material has gone down a flue serving a gas appliance — a gas fire, a back boiler, or any appliance sharing that stack — this becomes a carbon monoxide question rather than a wildlife one.

A partially blocked flue can spill combustion products into the room, and carbon monoxide has no smell. So: turn the appliance off, do not use it, and get a Gas Safe registered engineer to check the flue before it is used again. That check is not something a pest controller can do or sign off, and it is not something to defer.

If you do not have a carbon monoxide alarm in that room, this is the moment to buy one regardless of the squirrel.

What we do

Access, Then the Cowl

Where an animal is alive and reachable, the aim is to get it out — through the appliance opening, a soot door or from the top, depending on the construction. Sometimes that works and sometimes it does not, and a flue that has to be opened up is a builder's job as well as ours.

Where there is nesting material, it is cleared. Whether a chimney sweep is the right trade for that part depends on what is up there, and we will tell you straight if it is.

Then the actual fix, which is the same as everywhere else on this site: close the way in. A properly fitted cowl or birdguard on the pot ends this permanently, and it is cheap relative to everything above. If you have several pots and one is open, expect the open one to be used.

Fit the cowl after the flue is clear, not before. The logic is the same as sealing a loft with something inside it.

The disused flue

Capped Is Not the Same as Sealed

Plenty of houses here have flues that were taken out of use when a fireplace was blocked up, and those are prime nest sites: dry, sheltered and undisturbed, with nobody underneath to notice.

A flue capped at the bottom with a vent and left open at the top is an invitation. If you have redundant stacks, having the pots cowled is worth doing before anything happens rather than after, and it is cheaper as planned work than as an emergency.

Do not seal a disused flue completely top and bottom, incidentally. It needs some ventilation or you get damp in the stack. Cowl it, vent it at the bottom, and it stays dry and stays empty.

Short answers

Squirrel Questions

Going further

Squirrel Guides