Chimney Functions

Smells often induce nostalgia. Last week, on the evening dog walk, the familiar smell of burning wood, and the visual sight of white smoke rising from our neighbors’ chimney inspired a feeling of comfort. As temperatures fall in the Triad, and debates continue in households over when the heat can be turned on, a wood burning fire in the fireplace is a fine compromise.  I can say, with a high level of confidence, that people enjoying their wine or tea by the fire don’t appreciate all the functions of their chimney.  

Chimneys are a major component of your home inspection, and your chimney needs to be functioning properly. A chimney is a vertical device (usually masonry or metal), and its major function is to remove the exhaust products from burning fuels from the house safely. Chimneys may see different fuels. Wood is a fuel that burns hot and may be quite dirty. Creosote tends to build up in chimneys serving fireplaces and wood stoves. Burning oil is somewhat cleaner, but soot can often develop from incomplete combustion. When burning gas, which is the cleanest of the fuels mentioned, condensation can be a major issue because of the low temperature produced and the large volume of water created during the combustion process.

It is also the chimneys job to contain the fire.  Good chimneys minimize the heat loss from the home while in use AND while idle. They also should keep water out of the house, and not interrupt roof drainage systems, and should be flashed at roof penetrations. Chimneys should not allow water entry into the home through the top, sides, or bottom of the chimney. They should help keep animals, birds, and other pests out of the house.  Lastly, while not a home inspection point, a chimney should add to the architectural appeal of a home.

As you can see, a chimney has many important jobs beyond providing comforts. We will dedicate many future blogs to explaining these key functions in more detail. In the meantime, check out this list below for some common misconceptions and general information to keep in mind.

  • Homes with electric heat, high-efficiency furnaces (and some mid efficiency furnaces) may not have a chimney. This is okay, and not considered a defect.
  • Chimneys are not intended to hold up other building components. It is not appropriate, for example, to strap a satellite dish, or television antenna to a chimney. If we find this, we will write it up as a defect in your home inspection report.
  • Chimneys are actually not energy efficient. Fireplace chimneys pull in house air to remove combustion products from the home, so while they do provide heat, the net effect is actually heat loss! More on this later!!

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