Chimney caps are an essential part to your chimney system. This protects against rain, animals and debris from getting into your home. It can be detrimental or even deadly to neglect putting a cap on. These are designed to fit over the opening of your flue and are premanufactured to fit the specific opening of your chimney. Prefabricated systems have specific caps corresponding to the make and model but masonry chimneys have generic flue tile sizes that caps are constructed to fit. When the chimney has two or more flues venting through the chimney a custom cap is recommended. This is measured to fit around the outside of the entire chimney. Chimney caps can be constructed from a variety of metals. This will determine how long the cap will last before water erosion reduces the integrity of the metal and creates pinholes allowing water into the system.