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Why are my Walls Sooty?


About Sooty Walls
Fireplaces, Furnaces, Chimneys... and Candles?

Soot on your walls indicates a problem somewhere in your house, and you often don't notice soot until it's become a huge problem.
Most often, you move a picture on the wall and notice the telltale signs of soot. Upon closer inspection, you'll probably find stains on carpets, drapes and other home furnishings as well. Ductwork can pickup soot particles and quickly spread soot throughout your home, evidenced by soot stains around registers and embedded into your air intake or filter.
Before addressing cleanup, let's address the cause.

First, if you notice soot stains around your fireplace or hearth stove, you may have found clues to the culprit. However, a byproduct of burning any fuel is carbon. If your fireplace or stove is a vented model, the problem is the venting system, not the appliance; the venting components, connector pipe, chimney liner or the chimney design itself are to blame. Either look for excessively dirty venting, a blockage such as a bird's nest, or improper maintenance of the appliance. A fireplace or stove that has not been properly maintained may produce more smoke, fumes and particulates than the venting system was designed to withstand. Have the appliance cleaned and serviced, have the chimney cleaned and inspected.

Again, gas and oil furnaces are designed to vent fumes and soot out of the house. A properly installed and maintained furnace that's connected to a well designed chimney and venting system should show no signs of soot. If you see soot near your furnace, have the appliance cleaned and tuned for optimum performance, then have the chimney and venting system inspected. If the venting system is oversized, undersized, contains offsets or has been blocked by leaves or birds nests, make corrections immediately. If you upgraded the furnace but attention was not given to the venting system then your furnace may not be able to perform at its optimum, and may actually be dangerous. Additionally, consider the needs of a water heater, especially if the water heater shares a flue with your furnace. The water heater may perform well in the winter when rising flue gases from the furnace assist draft, but not these fumes may linger during warm months when the chimney lacks sufficient draft to evacuate fumes.
Be aware that soot caused by burning fuels (oil, gas, wood, coal) indicates another great potential health and safety risk of exposure to carbon monoxide. Soot is carbon, and where there are carbon stains then carbon monoxide has also been present. Carbon monoxide exposure can cause flu-like symptoms. Exposure to abrupt high concentrations, or long term low concentrations, can lead to permanent health damage and even result in death. If dirty walls are not enough motivation for you to immediately address your soot problem then the health and safety concerns of carbon monoxide should spur you into prompt action. Every home should have carbon monoxide detectors and smoke detectors installed relatively close to each fuel burning appliance, and on every floor of the home.
A knowledgeable chimney sweep can also point out design flaws in the venting system - such as a flue that's too small, too short or with improper offsets - that may prevent adequate venting. If the appliance is in good repair, the chimney is clean, unblocked and designed properly then the chimney should perform its job of carrying away fumes and smoke. If not, your house design may be at fault, not allowing sufficient combustion air to enter the house. Research negative draft issues and how house designs may encourage other appliances to pull combustion air INTO your chimney.

Yes, candles can cause thousands of dollars in damage to your home before you even realize this is where your soot stains originated. The worst culprits are imported candles using petroleum byproducts and/or lead wicks. Combine these ingredients with the chemicals added to manufacture scented candles and you may have a real soot maker on your hands! Most candle manufacturers recommend keeping wicks trimmed to 1/4" as this promotes a more even burning that results in less soot. Also keep candles away from drafts that visibly affect the flame. Never blow out a candle as this produces smoke and soot; extinguish the flame with a candle snuffer or by suffocating the fire by putting the top on a jar candle.
Soy and beeswax candles are generally preferred to parafin wax (a petroleum based byproduct). Soy and beeswax are renewable resources that burn cleaner and with less chemical additives. While they generally are more expensive to purchase, they burn longer and more cleanly than paraffin wax. Non-cored wicks made of natural plant fibers are also safer and cleaner burning.
Candles are a source of open burning fire in your home and should only be used with extreme caution any way. Don't burn them for hours on end; extinguish the the flame after one hour, and allow the candle to cool completely before relighting. Don't burn candles unattended, and make sure the wax is properly contained as the candle burns down.

Once you find and remedy the cause of your soot stains, it's time to begin the cleanup job. A variety of consumer-grade cleaners are available that claim to clean up soot stains. They're certainly worth a try, but commercial cleaning products and a professional cleaning team may be in order, followed by repainting and replacement of carpeting and furnishings in extreme cases.
While soot damage is sometimes covered by your homeowner's insurance policy, the company will generally investigate the cause of the soot. Insurance policies often cover a "sudden occurrence" event - such soot caused by a kitchen stove flareup - but won't necessarily cover damage that's occurred over a long period like that caused by candles. Chemical analysis of soot can determine whether it's caused by an improperly vented fireplace or by candle wax, so expect large cleanup claims to be investigated thoroughly.

Make sure the venting system is properly designed for the appliance it services
Have all fuel burning appliances cleaned, tuned and maintained annually for optimum performance and efficiency
Have all chimneys and venting systems inspected annually and cleaned when needed to eliminate excessive buildup
Use candles with extreme caution
Install smoke and carbon monoxide detectors in your home

This article reprinted with permission of THE FIREPLACE CHANNEL