Correct Fireplace Footings

Masonry Chimneys and Concrete Footings

• Building codes may differ slightly from area to area, but throughout the United States, some laws apply to all fireplace footings. For example, the chimney that rises from the footing must be created from non-combustible masonry material, such as brick, concrete block or a type of sturdy stone. The footing itself must be made from concrete and be heavy enough to support the chimney without settling, which means the chimney size may determine the footing size.

Soil Requirements

• The soil below the foundation where the footing is installed should be undisturbed or, even better, well-compacted. This prevents the footing from settling further into the ground as the soil slowly compacts, losing tiny spaces of air. This type of settling can ruin a fireplace, so proper preparation, before the footing is laid, is key.

Thickness

• The footing thickness should usually be 8 inches for a normal slab designed to support a fireplace and chimney in a one-story house. If you have a two-story house, prepare to increase the thickness to 12 inches since the extra chimney height needs to be supported. This is a 12-inch minimum that must extend from the ground level down to the foundation itself.

Width

• The width of the footing will also be determined by the size of the fireplace and its chimney. As a general rule, you will need to bring the footing out at least 6 inches on every side of the fireplace wall. This helps prevent heat from traveling into nearby materials and weakening them or catching them on fire when the fireplace is used.