A chase cover is a metal covering designed to keep elements like rain and snow, from entering the home via the chimney chase.
Over time almost all non stainless steel pre-fab chimney chase covers rust due to the elements. Snow, ice and rain gets trapped on top of your chase cover and starts the decaying process. Leaves and pine straw also mixed with the moisture creates an acidic condition and breaks down the galvanized coating of your chase cover.
When this breakdown occurs the chase cover begins to pit. This will allow water to drip inside your chimney. Let this rust stain be your sign that it is time to replace your chase cover.
It is recommended when replacing your chase cover to use stainless steel. Stainless steel is more durable, stronger and will look new for a longer period of time. It is also recommended that the chase cover be designed with a cross break which creates a “dome” effect. This will prevent the snow, ice and water from pooling on top of your chase cover. Stainless chase covers come with a lifetime guarantee against rust and corrosion.