It is a curious thing…you do not see many uncapped vents but you sure do see a lot of uncapped chimneys — and on the same roofs! We could venture some speculation about why that is, but the truth is, it defies all common sense. It is good that the venting is capped, but – given the importance of chimney caps, there really should be more of them up there.
Keeping Water Out
A chimney cap needs to be on every chimney. It is the chimney’s first-and-last defense against rain. This is its primary importance, because water absolutely has to be kept out of a chimney and the flue is otherwise unprotected. A chimney cap prevents the deterioration of your chimney because water can destroy a chimney a lot faster than it cut canyons.
This is why certified chimney sweeps make such a big deal of keeping crowns and caps and flashing in good condition. When cracks form in mortar or a chimney cap rusts, water seeps in and begins its self-sustaining increasing destruction of the chimney. Water follows water as surely as dogs follow dogs, and it creates bigger and bigger passages for itself.
A Fitting End
Keeping it out of the flue is a chimney cap’s first job and it needs to do it well. That means it has to be properly designed and fitted to your flue, and it has to stay in good condition. When all of that is achieved, a chimney cap of any kind improves the drafting performance of the flue.
Presumably, though, you want a cap of just the right kind for your chimney, and determining which one that is can be tricky. It involves lots of variables, and –given its importance – the smart move is to consult a certified chimney sweep. This ensures that everything is done properly and in good shape for the upcoming season.