Does Your Chimney
Really Need a Chimney Cap?

Not all chimneys come with chimney caps. And in fact, depending on the chimney type and its specific design, it may not require a chimney cap at all. Here we try to look at the advantages and disadvantages of using chimney caps for different types of chimneys.

Metal chimneys, more often than not, come with chimney caps already in place. These metal chimneys are used with prefabricated chimney installations, wood stoves, and gas venting systems. These metal chimneys need chimney caps or terminations because, for one, they do not have provisions for catching rain. That is, if it rains and your metal chimney is uncovered, the water would just run into your stove or fireplace, possibly ruining it.

Another reason is that birds and other animals would like the warmth of your chimney, and may clog it with nests and the like. Having a chimney cap would help to keep the chimney clear and free of animal infestations.

The last reason has to do with how these metal chimneys are designed. They often consist of layers of metal with air as insulation between the layers. Without a chimney cap, air and water might get into these insulation layers and affect the functioning of your metal chimney adversely.

Masonry chimneys, on the other hand, may or may not have a chimney cap. In this case, there are also possible disadvantages to using a chimney cap as opposed to leaving the masonry or brick chimney uncapped.

The disadvantages of using a chimney cap with a masonry chimney are as follows. First, a bad chimney cap can reduce or hinder the draft of the chimney. Secondly, some chimney caps come with screens which may become clogged and hinder the performance of your stove or fireplace chimney. Third, creosote and tar might collect on the chimney cap, and then run down the outside of the chimney, causing unsightly discoloration. And lastly, these chimney caps, because they are not built-in, need to be installed and re-installed if the previous one breaks or is blown off.

As we can see, using a chimney cap makes more sense with metal chimneys than with masonry chimneys.