What Is the Ash Pit in a Fireplace For?

An ash pit is a compartment at the base of the fireplace that holds fireplace ashes. This compartment, usually a cavity surrounded by cinder blocks or concrete, is reached through a small metal access door mounted flush in the fireplace floor or wall. Open the door and sweep ashes into the holding pit until they can later be removed.

Designed to hold old fire ashes, fireplace ash pits range from large pits holding years of ashes to small pits holding ashes from a few fires. These pits are recessed in masonry or other fire-resistant materials so that hot ashes do not accidentally reach wood or other flammable materials. Metal dump doors are heat-resistant steel or cast iron, as they are exposed to direct fireplace heat. The dump doors fit over a brick-sized opening leading to the pit. Many fireplaces have cleanout doors, often located outside the home at the chimney, so that old ashes can be shoveled out of the pit.

The ash pit is built at the fireplace base so that old ashes are swept or scraped into the ash pit and a fresh fire can be built in a clean fireplace. When ashes are shoveled or swept out of the fireplace opening into a room bucket, a spark or ember can fly into carpet or drapes, smoldering until it catches fire hours later. If hot ashes are instead swept into the ash pit, they are smothered by old ashes or burn out harmlessly. Depending on its size, the ash pit may hold a season's ashes so that it does not need emptying in inclement weather.

Ash pits need minimal care. They require emptying before they are full so that doors are not clogged with ashes or wood embers. When doors corrode from the ash lye or other exposure, the doors usually can be replaced with standard doors. The dump door, for example, is often a standard size that lifts out and is replaced by a drop-in new door. Ash pits should be kept closed during fires. They are designed for ash storage, not as fireplace extensions, and are not intended to ventilate the fireplace.

Remove ashes from the pit and put them in a metal bucket or other nonflammable container. Be sure the ashes are completely cold before dumping them into a trash bin or other receptacle. Many gardeners spread ashes on their lawns or gardens, but wood ashes are highly soluble and leach lime into the soil. This affects the soil nutrients. Apply wood ashes no more than once a year and test the soil pH level before reapplying ashes.