Fireplace Footing Requirements

Materials

• According to Section 2111.2 of the International Building Code, the footings of masonry fireplaces and their chimneys need to be constructed of concrete or solid masonry. Examples of stone materials that commonly comprise such masonry include marble, brick and granite. More specifically, concrete and masonry fireplaces must be at least 12 inches thick and need to extend at least 6 inches beyond the foundational wall -- or face of the fireplace – on all sides.

Footing Foundations

• In order to comply with International Building Code, fireplace footings must have foundations that are built upon engineered fill -- such as mixtures of sand, silt clay or fine-grained gravel -- or natural, undisturbed soil. In addition, the foundations must reach below the frost depth. Also known as the frost line, the frost depth is the level below which groundwater no longer freezes. A foundation that is above the frost depth is subject to movement and cracking as a result of the seasonal freezing and defrosting of the underlying ground. In areas that are not subject to ground freezing, fireplace footing foundations must be at least 1 foot below finished grade.

Drainage

• To prevent leakage problems, fireplaces should have a continuous array of drainage tiles around the exterior perimeters of their footings. This is an especially relevant consideration when adding a fireplace to an exiting house, as drainage tiles can sometimes be disrupted during the construction process. Basement fireplaces are particularly prone to leaking as a result of a lack of adequate footing drainage.

Passing a Home Inspection

• In addition to meeting the above-mentioned material, foundation and drainage requirements, a fireplace footing must be free of structural problems in order to successfully pass a home inspection. Some of the most common fireplace footing problems include cracking, settling and heaving. Cracking can be the result of several underlying issues, including concrete shrinkage, roots growing beneath the footings, poor soil conditions, and deterioration. The most troublesome footing cracks, however, are the result of settling and heaving, as these cracks may lead to structural failure and the collapse of the fireplace and chimney. Settling occurs when the fireplace footing shifts downward or “settles” into its underlying foundation. The opposite, heaving, occurs when soil expansion forces the fireplace footing upward.