Shallow foundation

Generally, each column is set on an individual footing to transmit and distribute the load of the structure to the soil underneath.

This type of footing is used when the structural load is relatively low, columns are widely spaced, and the soil's bearing capacity is adequate at a shallow depth.

This type of construction is most often seen in warmer climates, where ground freezing and thawing is less of a concern and where there is no need for heat ducting underneath the floor.

Over the long term, ground settling (or subsidence) may be a problem, as a slab foundation cannot be readily jacked up to compensate; proper soil compaction prior to pour can minimize this.

While elevated structural slabs actually perform better on expansive clays, it is generally accepted by the engineering community that slab-on-grade foundations offer the greatest cost-to-performance ratio for tract homes.

Signs of a slab leak range from unexplained dampened carpet spots, to drops in water pressure and wet discoloration on exterior foundation walls.

[5] Copper pipes must be lagged (that is, insulated) or run through a conduit or plumbed into the building above the slab.

Electrical conduits through the slab must be water-tight, as they extend below ground level and can potentially expose wiring to groundwater.