What Should You Do If an Animal Is in Your Chimney?

The first ten minutes

Nearly every animal in a chimney came in from the top, through a flue with no cap or a cap that has rusted open. Some fell in by accident and cannot climb the smooth clay tile back out. Others moved in on purpose to nest. Either way, the immediate job is containment: keep the animal inside the chimney and keep people and pets away from the opening.

Resist the urge to look. Opening the damper to peek, or opening a basement cleanout door, is how a panicked squirrel ends up running laps around a living room.

• Close the damper and any glass doors or mesh screen on the fireplace
• Keep pets and children out of the room and shut its door
• Do not light a fire, burn paper or put smoke into the flue
• Leave the basement cleanout door closed
• Write down when you hear noise and what it sounds like

Reading the noise

Sound is the strongest clue before anyone puts a light into the flue, and it changes who you call. A bird and a raccoon are different jobs with different tools.

• Birds: chirping and wing flutter in daylight, often loudest at feeding times; a steady chatter in summer can mean chimney swifts nesting on the flue wall
• Squirrels: quick scratching and scrabbling in the morning and late afternoon, sometimes followed by silence when one is stuck
• Raccoons: heavy climbing, thumps and churring at night; in spring, chattering young on the smoke shelf
• Bats: faint squeaks and a papery rustle around dusk and again before dawn
• A smell with no sound: an animal may have died in the flue or on the smoke shelf

Fireplace flue or boiler flue

Where the animal ends up depends on which flue it fell into. In a fireplace flue, it usually lands on the smoke shelf, the ledge behind the damper, or on top of the closed damper plate. In a flue that serves an oil or gas boiler or a water heater, there is no damper to stop the fall, so the animal drops to the base of the chimney, behind the cleanout door, or sits near the thimble where the metal flue pipe enters the masonry.

That second case is the more serious one. A nest, a body or a pile of debris at the base of a heating flue can partly block the exhaust path, and a blocked flue can push combustion gases back into the house. Carbon monoxide gives no warning you can smell, which is why a CO alarm belongs on each floor. When one goes off, or someone in the house turns ill, leave first and phone 911 or your gas company from the sidewalk.

Raccoons on the smoke shelf

In late winter and spring, a female raccoon looking for a den finds an uncapped fireplace flue and a wide, dry smoke shelf just above the damper. That is where litters are raised. You may hear the young before you ever see the mother, who climbs out at night to feed.

Do not try to trap or remove young yourself, and do not seal the top while the family is inside, or the mother may tear into the roof or the cap to get back to them. A wildlife professional plans the removal so the family leaves together. Nesting material and droppings left on the shelf are a health concern and a fire load, so that cleanup belongs to a crew with gloves, respirators and the right vacuum.

Bats need a different plan

Bats do not fall in; they roost. The New Jersey Department of Health notes that bats can squeeze through openings as small as three eighths of an inch, and lists crevices around the chimney among common entry points. So a chimney with a cap can still hold bats if there are gaps at the crown, the flashing or the mortar joints.

Timing is the main rule. The Pennsylvania Game Commission advises against sealing bats out during June or July, because flightless young would be trapped inside, and recommends sealing entrances after the bats leave in the fall. Exclusion with one-way exits comes first and is wildlife work; the chimney repairs that keep them out come after. Protection rules differ by state, so check with your state wildlife agency or a licensed wildlife professional before anything is done.

How animals find a way in

The usual culprit is simply an open flue. Many older brownstones, rowhouses and pre-war brick homes have several flues in one stack: a fireplace on each floor plus the heating flue, and often only one or two of them were ever capped. An unused fireplace flue with no cap is the easiest den in the neighborhood.

Less often, the way in is damage. A cap whose mesh rusted through, a cap that blew off in a nor'easter, a crumbling mortar wash with gaps around the flue tiles, or flashing pulled away from the brick can all give a squirrel or a bat enough room. On a party-wall stack that also serves the neighbours, a cap on your neighbour's flue does nothing for yours, so each flue needs its own protection or one full-width cap over the whole top.

When the noise is beside the chimney, not in it

Sound travels along masonry, so scratching that seems to come from the fireplace is sometimes in the wall cavity, the attic or the ceiling space next to the chimney breast. Squirrels and mice often run along the gap between the brick and the framing, especially where flashing has lifted at the roof line and left an opening into the attic.

A few clues help sort it out from inside. Noise that moves sideways along a wall, or continues above the top floor ceiling, points to the framing rather than the flue. Noise that stays put behind the damper, gets louder when you stand at the hearth and stops dead when the animal rests points to the flue. A technician confirms it by opening the damper with the room sealed, looking up the flue with a strong light and checking the attic side of the chimney for gaps, droppings and chewed insulation.

After the animal is out

Once the animal has been removed, the chimney work starts. Nests are pulled out of the flue and off the smoke shelf, the flue is swept, and the damper is checked for bent plates or a jammed handle, since animals often fight with it. On a heating flue, the base is cleared through the cleanout and the thimble connection is checked so exhaust can leave freely.

Then the top is closed properly: a cap with mesh fine enough to stop birds and squirrels, screwed or anchored down so it cannot be pushed off, on every flue that needs one. Cracks in the crown and open joints are noted, because a capped chimney with gaps lower down still lets bats in. Pro 1 Chimney handles this part with its own crew, so describe what you heard when you call.