What is a Chase Cover?
Factory or pre-fab chimneys are just a pipe made of galvanized or stainless steel. This style of chimney is used primarily in new construction for manufactured fireplaces or free-standing wood stoves. A chimney chase is a box that is built around this pipe, in order to make it look like a traditional masonry chimney. A chase is decorative, but also insulates and makes the chimney more efficient.
A chase cover is a metal cap that fits on top of the chase and covers the entire top of the chimney. This cover prevents water or snow, as well as debris and animals from entering the interior of the chimney structure. More importantly, it also serves as a spark arrestor, which will trap sparks inside the chimney structure so they cannot cause fires. Some states require covers for this reason, so check your state’s regulations.
Original chase covers are usually made of galvanized sheet metal or aluminum, which are inexpensive, but not very durable. Low spots in the structure will catch water and rust, which can stain the siding of the house during rains. In some cases you can hear the sound of water dripping inside the chase, which indicates the cover has rusted through. Rotted covers can cause major problems: firebox deterioration, heat and carbon monoxide leaks, mold, and damage to the structure of your home.
It is best to act when you first see rust stains on the chase cover, in order to prevent more extensive damage. A chimney professional can investigate and recommend whether or not it’s time to replace the cover. A good cover will have diagonal creases, called cross-breaks, to prevent standing water and will be made of stainless steel or copper. Both will not rust and usually come with a lifetime warranty. Copper, while highest in quality, is the most expensive choice.
Professional fitting and installation are important, since the chase cover will not be able to do its job if it is not the correct size, or is not installed properly.