We've said it before but it bears repeating: A chimney without a chimney cap is essentially a hole in your roof, providing entry for all kinds of critters, debris, and weather elements into your flue and into your home. You wouldn't leave your window open and your home accessible to these things—why would you leave your roof open?
What is a chimney cap and how much does it cost?
Priced starting around $150 (with installation), a cap is a minimal investment with a high return in the form of damage prevention and minimization of wear. A chimney cap is a metal top that attaches to the flue tile, covering the chimney flue (the opening in your chimney)—either the fireplace flue or the utility flue. They can be found in aluminum, stainless steel, copper, and other metals. Galvanized steel and aluminum are on the lower end of the durability (and cost) spectrum, stainless steel toward the center, and copper would be at the far end of the spectrum, offering much durability, but at a higher cost.
Why should I install a chimney cap?
One of the primary reasons to install a cap is to keep animals, who are drawn to the warmth of your chimney, from setting up house there. They often enter only to find that they cannot leave, then become trapped and die, at which point they become a nuisance and a health hazard (and extremely odorous).
A properly installed cap will also prevent leaves, twigs, and other natural debris from clogging up your flue and creating a fire hazard. Caps equipped with mesh screens (spark arrestors) help to prevent sparks from your fireplace from traveling up the flue and igniting your rooftop, potentially causing a house fire.
Covering that hole in your rooftop with a cap will also help to prevent downdrafts, the downward push of air that can cause smoke to blow back into your home when you have a fire in the fireplace.
Do false flues need caps?
The short answer is yes. False flues are flues that exist for aesthetic purposes only and do not serve to vent any gases or smoke. They are often filled with cement or otherwise closed up. However, even a false flue, though it is not a "hole," should be capped. A cap on a false flue (as well as a true flue for that matter) will divert water away from the clay flue tile and the concrete crown. Without a cap, water pools at the intersection of the crown and the flue tile and then freezes and expands, eventually cracking the crown, which then becomes a major and costly repair.
With all of the benefits of a cap, at minimal expense, one would be hard-pressed to justify not having one. Your chimney has a great role to play in service of your home and in its identity and value. Leaving it uncapped is practically an insult (lucky they don't have egos). So go ahead—close those doors and windows, and cap your chimney!
Wanna learn more about chimneys and chimney repair? Visit our chimney repair service pages.
Many thanks to our technician Ben S for lending his expertise to this article.