What causes a buzzing or humming noise inside a chimney flue?
The most common cause of buzzing inside a flue is a colony of stinging insects, usually bees, wasps or hornets, nesting in the chimney. A steady hum that rises on warm days and comes from inside the fireplace or behind the damper points strongly that way.
Phones answered around the clock · free estimate
The nuance is wind. Air moving across the top of the chimney, or a loose cap or damper vibrating, can also produce a hum or drone. If the sound only appears when it is windy and stops when the air is still, it is more likely airflow than insects.
Why it happens
A flue is a sheltered, dry, vertical tunnel, which is exactly what many insects look for. Bees and wasps can build a nest on the flue wall or just above the damper. The buzzing you hear is the colony itself, often loudest in the warmer part of the day when the insects are active.
Air can cause a similar noise. Wind passing over the flue opening can set up a low hum, and a loose cap, a damper that is not seated properly or a loose piece of metal can vibrate as air moves through. This sound tends to rise and fall with the weather rather than with the time of day.
A nest matters beyond the noise. It can partly block the flue, and the material and debris in it are fuel. Do not light a fire to drive insects out. Smoke can push them into the room, a burning nest is a common cause of chimney fires, and a blocked flue can send smoke back into the house. Stop using the fireplace until the cause is known.
What you can check yourself
Note when it happens
Listen at different times. A hum that follows warm sunny hours suggests insects; one that follows gusts suggests airflow.
Watch from the ground
Stand well back in the yard and look at the top of the chimney for insects flying in and out. Do not go onto the roof or approach the opening.
Leave the damper alone
Do not open the damper to look or listen more closely. If there is a nest above it, opening it can let insects into the room.
Keep the room calm and clear
Keep children and pets away from the fireplace. If any insects are already in the room, keep the doors to that room closed.
Check your alarms
Make sure the carbon monoxide and smoke alarms near the fireplace are working. Record a short audio clip of the noise to describe it to the technician.
When to call a technician
Call once you have heard buzzing more than once, or see insects around the chimney top or in the fireplace. Removing a colony safely is not a job for a homeowner with a spray can or a fire. Some species need a wildlife specialist or beekeeper, and in some places protections apply to certain insects and nesting animals. Check with your local building department or wildlife authority about the rules where you live.
If anyone in the house has a headache or dizziness while the fireplace has been in use, get outside and call 911. Otherwise, call One Call Chimney at (866) 576-7943. We arrange the visit with an independent chimney technician. The estimate is free, the technician inspects the chimney and gives you the price before any work starts, and you approve it first.
What the technician will do
- Identify what is in thereThe cause is established before anything is done, whether that is insects, a bird, or just wind and a loose part.
- Removal with the right specialistWhere the species requires it, removal or humane eviction is carried out with a wildlife specialist.
- Clear the nest and debrisNesting material and debris are taken out of the flue so nothing combustible or blocking is left behind.
- Sweep and inspectThe flue is swept and inspected. Ask to see the camera footage so you can see what was found.
- Fit a proper capA properly sized cap with mesh is fitted so animals and insects cannot get back in.
Related questions
- Can I smoke out the insects with a fire?
- No. A fire can push insects into the room and can ignite nesting material and debris, which is a common cause of chimney fires. Leave removal to a technician and a wildlife specialist.
- Could the hum be a loose chimney cap?
- It can be. A loose or badly fitting cap, or a damper that does not seat properly, can vibrate in wind. A technician can check the cap and damper during the same visit.
- Is it safe to use the fireplace if the buzzing stops?
- Not until the flue has been inspected. A nest may still be in place, and a partial blockage can send smoke into the room. Wait for the technician to confirm the flue is clear.
- How do I stop it happening again?
- The usual answer is a properly sized chimney cap with mesh over the flue opening. It keeps out insects, birds and other animals while still letting the chimney draw.
- What does the free estimate involve?
- A technician inspects the chimney, tells you what is causing the noise and gives you the price. No work starts until you have approved it.
Get a technician out
Free estimate. The price is agreed before the work starts.
Or send us a message
Leave your details and what is going on, and someone from the team will call you back.
More from One Call Chimney
Keep reading
One Call Chimney arranges the visit; the technician does the work and gives you the price.