A wood-burning fireplace makes any home feel warm and cozy. It is great for ambiance and is a good alternative source of heating. You enjoy the heat from the fire in winter, but once the nice weather comes around, you start noticing an unpleasant smell coming from your chimney. What causes it and how can you get rid of it?
Creosote and Soot
If your chimney smells like asphalt or bad barbecue, then you have creosote and soot build-up.
Creosote comes from wood smoke. It is a dark, flammable tar that is absorbed by the masonry inside your chimney.
Soot is black and powdery and is mostly made of amorphous carbon. It is produced by organic matter, like wood, that is not burned completely.
You cannot prevent creosote and soot from forming, but you can reduce the build-up by burning hardwood dried for a minimum of six months.
Have your chimney and fireplace cleaned at least once a year by a professional. It removes the build-up and prevents chimney fires. Since the odors are absorbed in the masonry, the smell will remain, but there are other factors to consider to prevent the smell from entering the house.
A smell of rot and decomposition means that leaves or other debris fell in the chimney and are decomposing.
Having your chimney swept fixes the problem, and installing a chimney cap prevents it.
If it smells of animal droppings or dead animals, that is exactly what is in your chimney. It happens that birds, raccoons and other small animals try to access your home by the chimney, but then get stuck and can’t get out.
A chimney cap with a mesh netting keeps animals out, and a good chimney sweep gets rid of the smell.
If you smell a musty odor coming from your fireplace, it means water got in your chimney.
Water does not only cause bad odors, but it can also rust the damper, and damage the flue lining, which will generate repairs.
A chimney cap stops water from entering your chimney, thus preventing all the problems mentioned above.
Negative Air Pressure
Even with a chimney cap installed and a clean chimney and fireplace, you can still smell bad odors if there is negative air pressure inside your home. This usually happens in newer homes that are sealed too tightly. How can negative air pressure cause bad odours to come into your house?
There are many pathways that allow air to go in and out of your home. It can be windows, doors, dryer vent exhausts, stove range fans and roof ventilation, among others, but the most prominent is your chimney. Air is always in movement. It goes out of the house through some of these pathways and is replaced by air entering through the pathway with the least resistance, which is usually the chimney.
When your fireplace is in use, the updraft causes the air to go out of the house, through your chimney, often faster than all other pathways combined can supply. That is why you do not smell the smoke when there is a fire burning. Once the fire dies down, the reverse effect happens. The other evacuation pathways take over, and the airflow in the flue reverses, which causes cold air from the chimney to come back inside, bringing the smell with it.
A quick solution to this problem is to always leave a window opened a crack. The replacement air comes from the window instead of the chimney.
Long-term solutions are to install a top-sealing damper controlled by a chain hanging down the chimney to the hearth. Keep it closed when the fireplace is not in use. Installing a glass fireplace screen also helps. You can also provide outdoor combustion air to the appliance that causes the air pressure problem.
Once the bigger problems are addressed, there should be no more bad smells from your chimney. The only unpleasant odor that can be left is the smell of ash. Removing it from your fireplace weekly helps prevent the problem.
You should have a professional clean your fireplace and chimney at least once a year, but there are a few things you can do to help eliminate the smell of ash.
Once your last fire of the season is done, wait at least four days. Use a stiff brush to clean the interior walls of your fireplace. You can then use a vacuum to clean the bottom of your fireplace or use the same brush to sweep it. In any case, put the ash in your outside trash bin right away. If there is more than 1/8 of an inch of creosote build-up, ask a professional to do it instead, as it is highly combustible.
To remove any odor, wipe the interior of your fireplace with white distilled vinegar. Dilute two cups in one gallon of water, and clean the sides and bottom of the fireplace and the grate with a scrub brush. Rinse the brush often. You can also replace the vinegar with all-purpose cleaner, and dilute it in the same way.
Once the fireplace is clean, odors can still linger in carpets and fabrics. You can deodorize your carpet by sprinkling odor-neutralizing carpet powder or baking soda on it. Let it sit for at least an hour, then vacuum thoroughly. You can finish off with an odor-neutralizing fabric spray.
Use the same treatment on upholstered furniture. You can use a bristle attachment on your vacuum. An odor-neutralizing upholstery shampoo can also be used.
Curtains can be washed in the washing machine or taken to the dry-cleaner. If washing at home, use baking soda to neutralize any odor. It’s even better if you hang them out to dry in the sun.
Soaking your blinds in warm water with a few drops of dishwashing detergent eliminates any ash residue that might linger. Wipe them down and rinse well.
The last step to remove any ash odor from the room is to wipe down all hard surfaces. Use heavily diluted dishwashing detergent or oil soap for the walls. On most furniture, you can use diluted white vinegar, oil soap or all-purpose cleaner. On tile and hardwood floors, use diluted vinegar or a steam mop. After cleaning a hard surface, wipe it with a damp rag and dry with a soft cloth.
Keep Your Air Clean
A fireplace is a great asset to any home. When maintained and cleaned properly, it is a joy to use. Yearly professional inspections and sweeps accompanied by a good spring cleaning will keep your fireplace in good working order, and the air in your house clean and pure.