First, stay calm and let the smoke clear

Smoke entering the room is alarming, but it is usually a solvable problem. Your first priority is safety and air quality. Open a window or an outside door near the stove or fireplace. This creates an escape route for the smoke and helps restore the pressure balance in the room. Do not open windows on the opposite side of the house, as this can make the problem worse by pulling air across the room and pushing smoke out of the appliance. If you have an extractor fan running in the kitchen or a bathroom fan nearby, turn it off. These fans can depressurise the house and starve the fire of air, causing smoke to spill instead of rising up the flue.

Check your air controls and damper

Once you can breathe comfortably, check the appliance controls. Most wood burning stoves have at least one air control, often a lever or a rotating wheel. Open the primary air control fully. If your stove has a separate secondary air control, open that too. On an open fire, look for a damper or a register plate lever. The damper should be fully open when the fire is burning. A closed damper is one of the most common reasons for smoke entering the room.

• Primary air: usually at the bottom of the stove door. It provides the main oxygen for combustion.
• Secondary air: often above the door. It feeds air to the top of the firebox and helps burn off gases.
• Damper: a metal plate in the flue or throat of an open fire. Open it before lighting and leave it open while burning.

If the fire is smouldering and the controls are already open, the flue may be too cold. A cold flue cannot pull smoke upwards. Try burning a piece of twisted newspaper or a firelighter near the base of the flue to warm it. You may see the smoke reverse direction and start to rise.

Diagnose the flue draught

Draught is the upward movement of air through the flue. Without it, smoke has nowhere to go but into your room. To test draught, light a match or a small piece of paper and hold it near the open stove door or the fireplace opening. If the flame or smoke is pulled steadily upwards into the flue, draught is present. If it lingers, blows back, or goes out, you have a draught problem.

Several factors affect draught. A flue that is too short, too narrow, or exposed to cold winds may struggle. A flue on an outside wall can be colder than an internal one. If your chimney is on the windy side of the house, downdraught can push smoke back down. Check for nearby tall trees, buildings, or hills that might cause turbulence. Sometimes a simple change in the weather, such as a still, damp day, is enough to reduce draught.

Common causes of smoke spillage

• Cold flue: the most frequent cause, especially first thing in the morning or after a long period without a fire.
• Blocked flue: nests, leaves, soot, or a collapsed liner can restrict the passage.
• Insufficient air supply: modern homes are airtight. If the stove cannot draw air, smoke will spill. Try opening a window a crack.
• Chimney height: a flue that terminates too close to the roof or a neighbouring structure may not draw properly.
• Poor burning technique: smouldering, wet wood, or overloading the firebox creates excess smoke that the flue cannot handle.

When to call a professional

If you have opened a window, checked the damper, opened all air controls, and warmed the flue, but smoke still enters the room, stop using the appliance. Call a qualified chimney sweep or a registered stove installer. Do not keep burning. Continued smoke spillage is a sign of a serious problem, such as a blocked chimney, a damaged flue liner, or a structural issue that needs expert attention.

When you call, be ready to describe the appliance, the fuel you are using, and when the problem started. Mention whether the smoke appears immediately on lighting or only after the fire has been burning for a while. This helps the professional diagnose the issue before they arrive. They may sweep the chimney, inspect the flue with a camera, or test the draught with specialised equipment. Never use a stove or open fire that smokes persistently. It is a health risk and a fire hazard.

Preventing smoke spillage in future

A little routine care will keep smoke going up and not into your room. Have your chimney swept at least once a year, and more often if you burn wood frequently. Only burn dry, seasoned wood with a moisture content below 20 per cent. Use a moisture meter to check. Warm the flue before lighting a new fire, especially in cold weather. Open the air controls fully for the first ten to fifteen minutes. Never close them down too soon. Keep an eye on the weather. On still, foggy days, draught can be weak, so build a smaller fire and give it more air. If you have an extractor fan in the same room or nearby, turn it off while the stove is lit. Finally, make sure your carbon monoxide alarm is working. Smoke spillage can also mean carbon monoxide is entering the room, which is invisible and deadly. If your alarm sounds, get everyone outside and call the emergency services.