Chimney Cap Advantages and Disadvantages

The Pros and Cons of Installing a Chimney Cap

By Mark J. Donovan

A chimney cap is a specially designed metal cover that is mounted on top of a chimney or fireplace. A chimney cover is designed to prevent water, as well as birds and small animals from entering the chimney. There are pros and cons to installing a chimney cap on top of a masonry chimney. Metal chimneys, on the other hand, nearly all require a chimney cap.

Chimney Cap Advantages on Masonry Chimneys

Installing a chimney cap on a masonry chimney has several advantages.

1) A chimney top can prevent rain water from penetrating into the chimney and eating away at the mortar and bricks. In addition, rain water entering a chimney can also sometimes lead to musty smells within the home.

2) Chimney caps can also prevent small animals and birds from entering the chimney.

3) Chimney caps can prevent fires caused by burning embers that exit the chimney. Countless fires are started every year due to burning embers that rise up out of the uncapped chimney and land on the home’s roof or yard.

Chimney Cap Disadvantages on Masonry Chimneys

Installing a chimney cover over a masonry chimney has several disadvantages.

1) An improperly sized, designed, or installed chimney cap can reduce a chimney’s draft which can lead to the poor burning of fuel and smoky rooms within the home.

2) Many chimney caps also have small screens on them to prevent birds and animals from entering the chimney however the screens can become clogged with soot and creosote, and again can lead to reduced draft.

3) Chimney caps can also rust over time and cause stains to form down the exterior chimney walls.

4) Unless fastened properly chimney covers can blow off the chimney in strong wind storms.

Chimney Caps and Metal Chimneys

Metal chimneys are commonly used today with pre-fab fireplaces, a.k.a. low clearance fireplaces, wood stoves, and gas stoves. Usually a chimney cap is required on metal chimneys because unlike a masonry chimney there is nothing to impede the flow of rain water down the chimney.

Without a chimney cap, rain water entering the chimney can quickly find its way into the fireplace or stove, and onto your walls and ceiling. In addition, most metal chimney liners have two or three layers. Rain water and moisture can find its way in between the layers and cause them to rust and corrode without a chimney cap.

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Chimney caps are also essential on metal chimneys for preventing birds and other small animals from building nests that can clog the chimney and potentially cause a chimney fire.

Selecting a Chimney Cap

It is imperative when selecting a chimney cap to find one that is designed for your specific chimney type and size. In addition, it is important that it is properly mounted so that the draft is not restricted and that it won’t blow off in a wind storm. Most metal chimney kits include a chimney cover that is specifically designed to cap off the chimney. Make sure to check with the store that you are buying the chimney cap from that you are selecting the right chimney cap for your particular chimney situation.

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