Every spring and summer many homeowners experience an issue with creatures causing damage to their chimney or even their house when birds, pesky squirrels, or even bats get into their chimney, prompting a call to a local chimney sweep or animal removal specialist. These issues can usually be avoided by taking some steps towards prevention.
Birds: Birds love to nest inside chimneys because they offer some protection from predators and are warmer than outside in early spring due to warm house air rising into the flue. Most birds build nests right on top of the smoke shelf or damper just on top of the fireplace, but Chimney Swifts build their nests on the sides of flue liners. Multiple bird nests may be inside a flue at the same time. Bird nests restrict the flow of flue gasses and are a fire hazard. Birds carry histoplasmosis, which can cause blindness. Therefore, it is best to avoid birds getting inside a masonry chimney by installing a heavy duty stainless steel chimney cover which has a cover to keep rain out and a screen to keep birds out. Don’t attempt to remove nesting birds however, as this is against the law. If you have nesting birds you’ll need to wait until the brood has left the nest to have the chimney cleaned and a cap installed.
Manufactured chimneys can be a unique problem when it comes to bird nests. Older double or triple-wall chimneys typically do not have an adequate bird guard screen to keep birds out of the chimney walls. This is usually difficult, and in some cases, impossible for a chimney sweep to correct. It may require removal of the entire chimney, removal of the nesting materials, and re-installation of the chimney, or in some case, replacement of the entire chimney and fireplace. Manufactured fireplaces are U.L. listed products that cannot be altered in any way.
Bird nests inside or on top of vents serving direct vent gas fireplaces are a newer, and concerning issue. Ask your chimney professional or gas service technician to check the vent for blockages, and to look on top of and inside the vent for bird nesting materials or do it yourself. Again, nesting materials inside a gas vent is a fire hazard, and if blocking the vent, a Carbon Monoxide hazard as well.
Bats: Bats love dark places, and will use a chimney if it is handy. Bats carry rabies, so don’t touch a bat if one escapes into the house, or try to remove it from a chimney yourself. A licensed animal removal expert should be called for this task. Keeping bats out of chimneys can be somewhat difficult since some species can get through a ½” space in a bird screen or even open mortar joints in brickwork. What is recommended by most chimney sweeps is the installation of a top-sealing combination damper and cap. This creates a complete seal at the top of the flue that bats can’t get through. If the chimney is missing mortar joints, have it repaired by a qualified mason.
Squirrels: For some reason, squirrels will occasionally build nests inside chimneys. Squirrels pack their nests very tightly so they are difficult to remove. Some chimney sweeps have reported removing 15’ or longer nests that took hours to remove. Obviously, the chimney flue cannot vent if this is the case, smoking will occur, and it is a fire hazard. Squirrels have been known to open dampers and enter homes as well, where in some cases they have caused thousands of dollars in damages. In one Kansas City case, the occupants left for vacation and when they returned found over $10,000 in damages to their home. Two squirrels chewed on furniture and woodwork, destroyed curtains and wallpaper, and ruined carpeting and wood flooring. Squirrels can be kept out of flues with a heavy stainless steel chimney cover available from your chimney sweep.
Raccoons: Don’t mess with a raccoon in your chimney. They can be very aggressive, bite, and carry roundworm and rabies. This is another creature to leave to a licensed animal removal specialist. After the raccoon and/or babies are removed to a safe location, have a heavy duty stainless steel chimney cover installed by your chimney sweep. Raccoons will tear up black steel and aluminum covers very easily so don’t waste your money on a cheap cover.
The Midwest Chimney Safety Council recommends that homeowners contact a professional CSIA Certified Chimney Sweep to diagnose animal entry points in or around chimneys and to correct the problem.