Why is Smoke Coming Out of My Fireplace

It’s a cold, chilly evening, and you’ve just lit your fireplace. You’re enjoying the warmth, but the entire house is filling with smoke from the fireplace, and you’re wondering why. Whether your fireplace is smoky occasionally or continuously, it’s a sign that there’s a problem that needs to be addressed. Smoke is bad for your health. It irritates the eyes and respiratory system and can lead to adverse health problems, including carbon monoxide poisoning.

Closed Damper

One of the most common causes of smoke coming out of the fireplace is forgetting to open the damper when starting a fire in the fireplace. When the damper is shut, smoke will quickly fill up in the flue and start coming out of the fireplace. Before starting a fire, always make sure the damper is open entirely.

Flue Obstruction

One of the common causes of a smoky fireplace is a flue obstruction. Creosote buildup, debris, and other materials can block the flue vent. The blockage prevents the venting of smoke and fumes, pushing it back down into the fireplace. Debris and creosote in the chimney are also a fire hazard. The high heat and hot embers can cause a chimney fire. Clearing the obstruction will allow the smoke to vent out the chimney instead of the fireplace, reducing fire and safety hazards.

Cold Chimney

Most homes have a fireplace that is built on an exterior facing wall. When temperatures drop, the cold outside air can make the flue as cold as a freezer. Starting a fire in the fireplace when the chimney is very cold can cause smoke to come out of the fireplace. The denser cold air creates a high-pressure system that prevents the hot air from rising and pushes it out of the fireplace. Warming or preheating the flue can alleviate the smoky problems of a cold fireplace. Simply roll up some newspaper, light one end with a match, and hold it up inside the firebox to warm the flue before lighting the fireplace.

Negative Air Pressure

The chimney needs to draw in outside air to start and maintain a fire in the fireplace. When there is insufficient oxygen, the negative air pressure can cause chimney draft problems, including a smoky fireplace. It typically occurs in homes with airtight insulation. Exhaust fans can also cause negative air pressure. If negative air pressure is the problem, opening a window near the fireplace will reverse the draft and solve the smoky problem. If the problem persists, an external air supply vent is a solution that will prevent a smoky fireplace.

Unseasoned Firewood

Freshly cut or “green” firewood has a high moisture content. The high moisture content will not only make fires smoky, but it will also create more soot and creosote, requiring more frequent chimney sweeping. It will also burn quicker, so you will need more wood to maintain the fire.

Always use firewood that has been “seasoned” or dried for at least six months. The low moisture content will burn cleaner with less smoke, soot, and creosote. Seasoned wood burns hotter and slower consuming less wood fuel.