Chimney maintenance 101

It’s been said that the most overlooked part of any home is the chimney. The last thing on our minds is the dark, dank chimney. It’s pretty basic, right? Smoke from the furnace goes up and out of it … end of story.

And it’s made out of bricks. What can go wrong?

A lot can go wrong, it turns out, from chimney fires to carbon monoxide poisoning. And chimneys are not just for homes with wood-burning stoves. Homes using anything but an all-electric heating system have a chimney.


With chimneys, as with anything that requires maintenance, an ounce of prevention is worth a pound of cure. The reason a chimney has to be inspected at least once every two years and occasionally cleaned has to do with the corrosive and flammable nature of the residue (creosote) that accumulates on the chimneys inner lining, or flue. If the chimney is not cleaned, eventually it will have to be relined, which is quite costly.

Chimney fires, in which creosote deposits ignite, represent the most extreme and explosive consequence of neglect. However, since the destructive power of such fires is usually contained and since they most often occur in homes with wood-burning stoves, they aren’t the most dangerous kind of chimney problem. That dubious distinction belongs to carbon monoxide poisoning.

The problem, as with out-of-control chimney fires, lies in the deterioration of the chimney’s flue, which in most chimneys is made of clay tiles. It is several feet long and of variable thickness. As it breaks down, carbon monoxide can pass through the more porous bricks and into your home.

One more piece of chimney knowledge: You’re inviting disaster if you have an older chimney with clay flue tiles hooked up to a high-efficiency gas or oil furnace. High-efficiency furnaces will destroy flue tiles within a year. Because the stack temperature is so cool (due to more heat from the furnace staying in the house), much more condensation occurs, accelerating corrosion.