People who own or operate woodburning stoves and fireplaces face several responsibilities, one of which is to keep burning embers from escaping into the neighborhood. It only takes a few sparks in a dry area to trigger serious brush or forest fires. This is why many communities require the use of a spark arrestor whenever a solid fuel fireplace or stove is in regular use.
There are actually two different types of spark arrestors that a person may encounter around a woodburning fireplace. The one mandated by regulation is an open-mesh screen placed securely over the top of the chimney stack. Manufacturers offer models in various sizes, according to the diameter of the chimney cap. This type should prevent any burning embers or sparks from escaping through the chimney.
Another type of spark arrestor can be either functional or decorative. It is generally a self-supporting screen or shield placed a short distance from an open fireplace flame. It serves the same purpose as an exterior screen, keeping stray burning embers from escaping from the fireplace and possibly starting a fire. Manufacturers offer reproduction models reminiscent of those found in castles or mansions, and there are many more basic, functional models suitable for regular home use as well.
Experts suggest that a spark arrestor should be large enough to protect the chimney from animals and debris, but small enough to allow a positive draft in the chimney. A functional exterior arrestor must be regularly maintained and cleaned, like gutters or the chimney's flue. A trained chimney sweep may be able to remove the mesh screen and clean it while performing other duties. If a professional is not available, then it falls on the owners to periodically sweep out accumulated dirt, ash and leaves from the external screen and dust the interior version.