footings

Footings are structural elements that transfer a building's loads to the underlying soil or rock. They form the lower part of a foundation system and help distribute weight to prevent excessive settlement. Footings are usually made of reinforced concrete, but can also be masonry, steel, or timber in small or non-traditional structures. They may be used alone or in combination with grade beams, piles, or other components.

Common types include spread (pad) footings for individual columns, strip footings for load-bearing walls, combined footings for adjacent columns with overlapping loads, and raft (mat) footings that distribute loads over a large slab area. In poor soil, footings may be supported by piles or be connected to piles via pile caps. In some designs, footings are built as continuous footings along a wall or as stepped or offset shapes to accommodate varying soil conditions.

While footings spread load in shallow foundations, deeper foundations rely on piles or drilled shafts that transfer loads to deeper strata; pile caps are a form of footing that connect piles.

Design factors include soil bearing capacity, footing size and thickness, reinforcement layout, eccentric loading, settlement limits, frost depth, groundwater and drainage, and construction tolerances. Codes and standards govern material strength, minimum concrete cover, and inspection requirements.

Construction involves excavation to the required depth, placing and securing reinforcement, forming and pouring concrete, and curing. Proper compaction around the footing edge and adequate drainage reduce moisture-related heave and settlement.

Reinforcement is used to resist bending and crack widths; in many regions footings are designed with concrete of specified strength and provide protective concrete cover to resist corrosion. Regular inspection ensures no movement or cracking.