Chimney Cover
- Necessary or Not?

Some chimneys come with a chimney cover or chimney cap, while others do not. Some people would have you believe that having an uncovered chimney would be bad, and yet some others would insist that it is perfectly fine. The real answer is - it depends. It depends on the type of chimney that you have.

Metal chimneys are becoming more common nowadays, as attachments to gas venting systems, wood stoves, and pre-built chimney installations. This type of chimney often comes with a cover already in place. This is mainly because of how these chimneys are designed.

Most metal chimneys consist of two or more layers of metal forming a tube, with a layer of air acting as insulation between them. What this means is that, if it rains, the water would get through to the insulation layer, affecting chimney performance significantly. Therefore it is very important for a metal chimney to have the appropriate chimney cover installed.

Furthermore, using a chimney cover with a metal chimney does not incur any significant disadvantages. So it would seem that if you have a metal chimney, having a chimney cover is in fact necessary.

But some chimneys are made of bricks or masonry. These chimneys are constructed differently from metal chimneys. The main reason why a metal chimney would need a cover, the fact that the insulation layer might be invaded by rain, is not applicable to a masonry chimney.

Masonry chimneys are made of bricks or similar materials, and so do not have any spaces for rain to go in, except for the chimney itself. Thus having a chimney cover is not of as much importance as it would be for a metal chimney.

In addition, using a chimney cover with a masonry chimney may result in a few disadvantages. For one thing, these chimney covers do not come pre-installed or pre-built into masonry chimneys. This means that they need to be installed - and re-installed if they break or are blown away.

A chimney cover that uses a filter might also become clogged eventually, with a masonry chimney that burns wood. This clogging would block the chimney partially, severely hindering ventilation and thus proper functioning.

Before going to get a chimney cover, make sure that your chimney really needs it. In some cases, the disadvantages of having a chimney cover might outweigh the possible benefits.