The Draft

Back some years ago, the draft was something to be avoided, with some young men going so far as to flee to Canada. Yet all along and it’s still true today a draft can be desirable in some instances, while in others not so much. The draft of which I speak has nothing to do with manning an army, but with air flow.

Since we humans prefer to stay warm, we have for centuries relied on burning something to produce heat. At first it was wood and it still is for many people, especially as the price of our more modern fuels has climbed. Since mankind has developed central heat sources that burn fossil fuels, burning wood became a sort of a novelty. Fireplaces were no longer for cooking and heating, but for use as a fun past time.

I can remember searching for my first house and wanting a fireplace. Many people still desire a fireplace on their house hunting list. There is something primal about sitting in front of a crackling fire on a cold winter evening.

Unless smoke gets in your eyes.

Fireplaces rely on a draft to vent the smoke up the chimney and keep it out of the house…and your eyes and lungs. But not all fireplaces do their intended job. This is not usually the fault of the fireplace. More often it is the location of the fireplace in the house and how the air in the house inhibits the draft.

Most often a fireplace will experience back drafting if it is located in the basement or lowest level of the home. Add to that a chimney located on the exterior and you have a smoker waiting to be lit. Simply there is negative air pressure at the lower parts of the home which is intensified as the outside temperature drops. Negative air pressure means instead of smoke going up the chimney, it will be force down. Almost like an imaginary hand of air pushing the smoke back down the flue into the room. As the chimney warms it will draft, but as it cools the smoke will then loose the air battle and once again enter the house.

A smoldering fire produces the most dangerous smoke as it contains a good deal of carbon monoxide.

The fireplace in the picture was from a recent inspection. When I saw the condition of the brick and mantel I was amazed. Amazed that the homeowners used the fireplace and didn’t die. The walls and ceiling were soot stained in the room. You could see the outlines of where the pictures had been hung on the wall, scary.

One interesting photo I found of the ceiling shows a draft created or actually accentuated by the burning fire and displayed by the soot stain. That is usually an undesirable draft. In this instance it may have brought in enough air to prevent the homeowners from succumbing to smoke inhalation.

James Quarello
Connecticut Home Inspector
2010 - 2011 SNEC-ASHI President
NRSB #8SS0022
JRV Home Inspection Services, LLC

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