Single Flue Chimney Cap Replacements

There’s some confusion about chimney caps. Generally, people refer to any device that covers some or all of the top of the chimney as a “chimney cap.”  This is not accurate. A chimney cap, defined by those who work in the chimney services industry, is a full-width covering over the entire top of the chimney including the flue opening as well as the chimney crown.

The small device you see on some chimneys that covers only the flue is a single flue chimney cap. If you have a single flue cap installed on your chimney, there are a few things you should know.

The Purpose of a Single Flue Cap

Single flue caps are in place to keep water from rain and snow out of the flue, where it can cause damage to the chimney liner and interior masonry. Single flue caps also prevent tree debris and small animals looking for a place to build nests out of the flue.

A third function – assuming the cap is built with mesh sides – is to keep fiery sparks and embers from popping out of your flue and landing on the roof or somewhere in the yard.

Chimneys & Water Damage

Bricks and water don’t mix. Water eats away at bricks and mortar and can end up destroying an entire chimney. When there are cracks in the chimney’s masonry, water damage comes in faster and more widespread.

Single flue chimney caps are no protection for a chimney’s masonry. Full-width chimney caps, however, do offer a level of masonry protection by channeling water away from the sides of the chimney. You should also consider waterproofing your chimney.

Mold Issues

Water that regularly flows into the flue creates a constant dampness that’s a perfect environment for the growth of mold. Some mold varieties are not especially harmful to live around; others, such as black mold, are known to cause severe respiratory problems and even cancer.

Both single flue chimney caps and full cover outside-mount chimney caps prevent water infiltration into the flue.

Chimney Crown Damage

Concrete is prone to cracking over the years. Chimney crowns made of this material are particularly vulnerable to the wearing effects of water and snow. Even small cracks can allow water to infiltrate and freeze and then expand, leading to a cycle of ongoing damage.

Full cover chimney caps offer great protection for the crown. Single flue chimney caps do not.

Chimney Flashing

The flashing that seals the gap between the exterior chimney and the roof may be warped or not securely sealed. Water can then get through and run down into the home, causing damage to building materials and the exterior masonry.

Single flue chimney caps do nothing to prevent this. The angled design of full cover outside-mount caps channel water away from the area where the roof and chimney connect. (Note that flashing should be inspected and repaired/replaced when necessary – don’t rely on your chimney cap alone.)

The Best Protection at the Top of Your Chimney

While a simple single flue chimney cap does have its advantages, it’s no match for a custom full cover outside-mount chimney cap when it comes to comprehensive protection of your chimney’s internal and external masonry, its crown and its flashing.

Fire N’ Stone of Tilton, NH, regularly installs a wide array of custom full cover chimney caps for our customers in Holderness NH, Center Harbor NH, Moultonborough NH, Plymouth NH, Concord NH, and other Lakes Region communities. Let us install one for you to give your chimney solid protection during all four seasons.

Learn more about the value of a properly built chimney cap by calling (603) 293-4040. A certified chimney expert will be happy to answer your questions and schedule an appointment.