Chimney Caps and Odors

By Robert Robillard on Uncategorized



Reasons To Use A Chimney Cap

A “Chimney Cap”  installs into the top of, and covers the chimney opening and protects the inside of the chimney, while still allows gases to escape.

Chimney Cap Functions

Chimney caps serve several functions, most notably:

  • Keeps rain and snow [freeze / thaw damage] from getting inside the flue and damaging masonry.   Rain can mix with creosote inside the flue damage the mortar and rust the damper.
  • Acts as a spark arrestor by preventing fire sparks from escaping from the chimney and landing on the roof.
  • Keep birds, squirrels and raccoons from entering the home through the chimney and setting up a nest.
  • Keep out leaves and other debris.

Chimney Odor

Sometimes people complain that they have a chimney smell.  The main question is to determine if your chimney cap is installed properly, chimney odor.

It’s a pretty common misconception that chimney caps cause draft problems, they do not. Most of the time the problem is due to installation or other factors. There are specifically designed chimney caps to reduce or correct draft problems. A properly installed cap should solve problems, not create them.

To be sure I covered all bases I called to my FAV chimney sweep he suggests looking for other factors contributing to or causing the smell.

He told me that your sweep MAY be correct in that some work is needed, assuming the cap lid is too close to the flue liner for either the boiler or fireplace flue.  Chimney caps need a MINIMUM of 4” for the flue to breathe. My chimney sweep likes to see it installed with a clearance somewhere around 5” or 6.”

His guess is that your chimney sweep will cut down the exposed flue tile with a grinder equipped with a masonry blade to create more clearance.

According to my sweep, none of the above, likely has any relation to your fireplace odor. Fireplace odor is often caused by moisture in the brick & masonry.

A chimney cap helps but does not solve this, as there is still a column of air in the flue containing moisture, for the brick to absorb, and in cases, a world of moisture outside if it’s an exterior chimney.

Wet Dog Syndrome

My sweep calls this “the wet dog syndrome”.  If you ever brought a wet, smelly dog in from the rain you know what I mean.

Another cause for odor may be that the wood is not burning completely and is leaving a tarry residue on the flue walls.

The residue is not just flaky ash, but un-burned combustibles. It takes a lot of experience to think of the proper solution. They can range from simple fixes to expensive repairs. In some cases switching to a gas insert may be the only solution.

If you enjoyed this post, make sure you subscribe to my RSS feed!

About the author

Robert Robillard

Carpenter / Remodeler / Editor

Rob Robillard is “The Concord Carpenter” Rob is a builder, general contractor, carpenter, woodworker, and editor of Concord Carpenter and ToolBoxBuzz As a General Contractor and carpenter, Rob owns and operates Concord Carpenter LLC. A full-service remodeling and construction company. Rob is a recognized leader in home building best practices and a source for how-to information for building professionals. On this website, Rob covers all aspects of home construction, building science, home improvement, woodworking, remodeling, and some of the best product and tool reviews. Rob is in charge of our Tool and Product Review series - Concord Carpenter Videos where we post all of our tool reviews and video tutorials. Rob approaches remodeling and building construction with a pragmatic and problem-solving approach. He enjoys using his knowledge and experience to help and educate building professionals as well as DIYers on best practices in the construction and remodeling industry. He's a strong advocate for "raising the bar" in the construction trades and promoting the trades to youth. #BeAMentor #Green2Great Craftsmanship, quality, and pride guide his journey on this channel The Concord Carpenter's motto: "Well done is better than well said!" : Read more about Rob

All posts by Robert »

Not what you're looking for?

Search for more articles here. Enter keywords like roof leak, bookcase, deck, etc to find your topic.

© Copyright 2019 A Concord Carpenter · All Rights Reserved