To a raccoon or a bird, an open chimney flue is a hollow tree with a roof over it. AM Chimney Sweep installs chimney caps and cleans, inspects and repairs chimneys in Millburn Township, including Short Hills, and animal entry is among the most frequent reasons we are called here in spring and early summer.
Why it happens here
Millburn sits beside a great deal of woodland. South Mountain Reservation, which Essex County describes as 2,112 acres kept largely in its wild state, runs through the township. Census Bureau estimates also show that about four in five Millburn homes are detached houses and a third were built before 1940, which means many tall masonry chimneys, often with more than one flue and not always with a cap on each.
Sources: Essex County Parks, South Mountain Reservation; U.S. Census Bureau, American Community Survey 2020–2024 five-year estimates.
Who moves in, and how you can tell
Raccoons
A female raccoon will use the smoke shelf just above the damper as a den for her young in spring. You hear heavy movement and, later, a chattering or crying sound from the kits.
Squirrels
Squirrels fall in more often than they move in. A clay flue is too smooth to climb, so they are trapped. Frantic scratching that does not stop is the usual sign.
Nesting birds
Twigs and nesting material dropped into a flue can block it completely. On a flue that serves a furnace or water heater, that blockage can send exhaust, including carbon monoxide, back into the house.
Chimney swifts
Swifts are small birds that nest on the inside wall of chimneys in summer and make a high, rapid chittering. They are protected under the federal Migratory Bird Treaty Act, so a nest with eggs or young cannot be removed. They leave on their own, and the chimney is then cleaned and capped.
What to do, and what not to do
- Keep the damper closed so nothing comes into the room.
- Do not light a fire to drive an animal out. It can kill the animal in the flue and fill the house with smoke.
- For a live raccoon or a trapped squirrel, contact a licensed wildlife control operator. Once the flue is empty, we take it from there.
- If you suspect swifts, wait. We can schedule the cleaning and cap for after they have gone.
After the animals: clean, inspect, cap
Nesting material is flammable and has to come out before the fireplace is used. We clean the flue, then inspect it with a camera, because raccoons in particular can dislodge damper parts and mortar. Then a cap goes on.
Choosing a cap
- Material: Stainless steel outlasts painted or galvanized steel, which rusts and stains the chimney.
- Mesh: The screen should keep animals out and help contain sparks, without being so fine that it clogs with soot.
- Coverage: A chimney with two or three flues can take individual caps or one larger cap that covers the whole top and shelters the crown too.
- Fit: A cap that is simply set on the flue tile can be pulled off by a determined raccoon. It should be fastened.
Every flue needs to be covered, including the one for the heating system and any flue that is no longer used.
Schedule service in Millburn or Short Hills
Call (862) 225-6529 or contact us online. While we are on the roof we also check the crown, since a cap and a sound crown together keep most water out. Examples of cap installations, including a crown repair and cap project in Montclair, are in Our Work.