If water gets in your chimney, it begins to do what it does everywhere else, sometimes to equally stunning degrees. It begins to corrode your chimney, slower or faster depending on materials and condition, but always increasingly. Ideally, its entry is prevented entirely and, if it does get in, it needs to be caught quickly.
There are three things you need for a chimney to be in good condition and clean. That means there are actually four things you need, with a professional cleaning and inspection being the first. The remaining three are a good chimney cap or shroud, a good crown or rain pan, and a water-proofing agent or sealant that breathes. They are all called different things in different cases but the functions they serve are the same.
An amazing array of choices exists for homeowners to choose from in selecting everything they need. That starts with chimney sweeps, and it is important to choose one that is certified by organizations like the Chimney Safety Institute of America and the National Chimney Sweep Guild. Again, that done, your sweep can actually help to inform your choice of cap, crown, and waterproofing agent. With so many options, it is important to understand “what you really want” given individual circumstances.
Most homeowners do not realize just how helpful chimney sweeps can be in assessing the secondary needs that determine what they want. Chimney caps can improve the draft of chimneys, and they need to withstand more than rain to greater and lesser degrees. The migration of birds even has to be a factor in the choice of the right chimney cap.
Making your chimney watertight at the same time that it remains able to properly let smoke out is tricky business. It is not something to entrust to those tricky enough themselves to skirt certification as qualified professionals. Remember that the first thing you need is a certified sweep and all the other lessons will be a lot less painful.