Chimneys, Inside and Out

Whether it is an extension of a fireplace or a furnace, you should have your chimney cleaned or "swept" at least once a year, for several reasons.

 First, creosote often adheres to the inside of the fireplace chimney. Because of its chemical nature, creosote can actually ignite, rapidly causing a chimney fire and potential damage to the rest of the home.

Burning wood at a relatively low temperature (your cooking stove flame is actually hotter than a fireplace) causes incomplete combustion of the oils found naturally in the wood. When the smoke from a fire rises into a chimney, the residual chemicals may stick to the inside of the chimney liner. This residue becomes creosote.

Second, soot and dust build-up can clog a chimney and diminish heat output. A furnace flue may accumulate a layer of sulfuric acid or chlorine, which can cause erosion and big problems down the road.

A good rule of thumb is to not ever assume your chimney is functioning properly, even if you rarely use it. Animals, leaves and moisture from a buildup of snow or rain need to be taken care of before safe use of your fireplace.

A thorough check for any shifting of the chimnye that may have occurred over the years is also recommended. Years ago, chimneys were built with a section near the top made of terracotta, over time, these sections sometime move, causing the potential for leaks of carbon monoxide through the seams and even a backdraft.

In addition to a good cleaning, chimney inspection includes checking for leaks in the flashing around the chimney, which can cause wood rot and condensation. This, in turn, can damage electrical wiring and present a fire hazard.

by  Joseph Coupal

When it’s time for annual fireplace maintenance, chimney sweep or do it yourself?

Regular maintenance and cleaning of your fireplace takes a little time but it will pay off in the long run allowing your fireplace to run at it’s maximum efficiency safely. First things first, an annual inspection of your fireplace/chimney is recommended by all local municipalities no matter where you live. Even if you have taken good care of your fireplace, animals can build nests, leaves can fall inside the chimney, vapors could accumulate and things you cannot see can also happen causing a possibly bad situation, maybe even hazardous.

Check out the Chimney Institute of America, it is a non-profit educational organization existing to provide chimney and venting safety resources to you, the homeowner. 

“The primary job of a chimney service professional is to aid in the prevention of fires related to fireplaces, wood stoves, gas, oil and coal heating systems and the chimneys that serve them. Chimney sweeps install, clean and maintain these systems, evaluate their performance, prescribe changes to improve their performance, and educate the consumer about their safe and efficient operation.”

When cleaning your wood burning fireplace, avoid chemicals and abrasive cleaners. For the glass, handles, and exterior surface, a soft damp cloth will work perfectly. “If you notice streaks or dirty glass, you can use a standard window cleaner such as Windex. Using a soft cloth, simply clean the glass while it is cool.”  

If you decide to clean your chimney yourself, the first task is to clean the creosote, the source of most chimney fires, out of the chimney. Running the proper-sized chimney brush up and down from the top of the chimney is the best method. First, seal off the fireplace opening in the room. 

Moisture is the main culprit in masonry chimney failures. Brick, concrete and mortar seem hard, but they are permeable to water. While you are up on the roof cleaning out the creosote, inspect the cement chimney crown. Brush away any loose pieces. If it is still basically intact and just has some cracks and pits, coat it with a elastomer crown repair material. You can select a brush- or trowel-on material. It stays flexible and seals better than mortar. 

A deteriorated/loose flashing can be another way for water to enter the chimney. Installing new flashing is best, but most homeowners find it much easier to use a flexible flashing repair compound. It is brushed on over the flashing. Next, inspect the mortar joints. Remove any loose mortar and fill it with mortar or a concrete-colored elastomer sealant. Finally, seal the entire chimney exterior with a water repellent. Be sure to select one which allows the masonry to breathe so moisture does not get trapped. 

There's no “one-size-fits-all” rule for how often to clean your chimney or what to use when you do it. It is always best to contact your local fire inspectors office and ask what they recommend before deciding on anything where your families safety is concerned.  

(information obtained for this article are merely recommendations by homeowners, not something that should be attempted without careful consideration.)