Understanding whether chimney caps are important for you is complicated. The best way for you to make a decision when it comes to choosing and maintaining a chimney cap is to consult a chimney sweep. Even more than your cap, their job is to stay on top of every component of your chimney.
First and foremost, the chimney cap needs to keep water out of the chimney, so it needs to be of the right size and slope. Poorly designed chimney caps are definitely out there, so ensuring that your choice is not among them is definitely important. If the cap is not directing water away from the flue, it might as well not be there at all.
Next, the cap has to keep debris, birds, and animals out of the chimney, but at the same time allow maximal drafting. Whether that is better solved on your roof with bars or mesh… is a good question to ask your chimney sweep, too. Migratory patterns, trees in the area, wind exposure, any number of things can impact on “the right cap” for this purpose.
Special Purpose Caps to Last
Every chimney cap improves a chimney’s updraft just by being there, but significant drafting problems can be corrected with “draft-improving caps”. The problems of course need first to be checked and the cause identified (again, a job for a CSIA certified sweep). If insufficient drafting is the only problem, it may be correctable with one of these specially designed caps.
Finally, in this introduction to your options, the durability-versus-cost issue is important in choice of materials. Again, so many location-specific and budget variables factor into this choice that you would do well to involve a chimney professional that works with chimney caps regularly. This will ensure that you are making the proper selections and decisions for your home and family’s safety and comfort.