Reference · Glossary
Every footing term a contractor or DIY builder runs into, defined in one plain paragraph each. Thirty-two terms, from spread footing and frost line to sonotube, rebar, and cubic yard.
A concrete footing is the widened base that spreads a structure’s load onto the soil; a foundation is the whole below-grade system — footings plus the walls, piers, or slab on top. Most other footing vocabulary describes either the shape of the footing, the ground it bears on, or the concrete itself. The list below runs roughly in that order — shape, then ground, then concrete — so related terms sit together.
The widened base of concrete at the bottom of a foundation that spreads the structure’s load over the soil. A footing is almost always wider than the wall or post it supports so the soil below it is not overstressed.
The whole below-grade system that transfers a building’s load to the ground — footings plus the walls, piers, or slab above them. The footing is one part of the foundation, not a synonym for it.
A footing that spreads a concentrated or line load over a larger soil area. Continuous wall footings and isolated column pads are both spread footings; the term contrasts with deep foundations like piles.
A long, uniform footing that runs under a wall the full length of the wall. Residential perimeter and interior foundation walls sit on continuous footings, which is why footing labor is billed by the linear foot.
A single square or rectangular footing under one column, post, or interior support point, poured as an individual unit and counted separately from linear-foot wall footings.
An isolated footing that carries a pier or post, common under decks, porches, and pole structures. A cylindrical concrete pier is often cast in a form tube on top of a wider pad.
A brand of waxed cardboard form tube used to cast round concrete piers and deck footings. Standard diameters run from about 6 to 36 inches; the tube sets the diameter while depth is set by the frost line and load.
A reinforced concrete beam that spans between piers or footings and carries wall or slab loads across softer soil. It looks like a footing but is designed to bridge, not just bear.
The concrete or block wall that rises from the footing to support the structure above. A stem-wall foundation is a footing plus a short wall, as opposed to a monolithic slab that pours footing and slab together.
The maximum depth to which soil freezes in a given location, from near zero in warm climates to 4 feet or more in cold ones. Footings must bear below it so freezing soil cannot lift them.
The upward movement caused when water in soil freezes and expands beneath a footing. Footings placed above the frost line can heave in winter and settle in spring, cracking walls and slabs.
A code-recognized method that uses insulation to keep the ground under a shallow footing from freezing, allowing footings above the normal frost depth for heated buildings. Governed by IRC R403.3.
The load per unit area a given soil can safely support, expressed in pounds per square foot (PSF). Weaker soils have lower bearing values and require wider footings to spread the same load.
Native, never-excavated ground that has not been loosened or backfilled. Footings must bear on undisturbed soil or on engineered, compacted fill — never on loose spoil.
One foot of length measured in a straight line, ignoring width and depth. A 40-foot footing is 40 linear feet whether it is 16 or 24 inches wide. Footing crews measure and bill work in linear feet.
The standard unit for ordering concrete: a volume 3 feet on each side, equal to 27 cubic feet. Ready-mix is sold and priced by the cubic yard.
A volume 1 foot on each side. Footing volume is calculated in cubic feet from width, depth, and length, then divided by 27 to convert to cubic yards for ordering.
Concrete batched at a plant and delivered wet by truck, ordered by the cubic yard. It is the economical choice for anything beyond roughly one cubic yard — most footing pours.
Dry pre-mixed concrete in 40, 50, 60, or 80 lb bags, mixed on site. An 80 lb bag yields about 0.60 cubic feet; bags only make sense for small pads, short runs, and repairs.
A percentage added to the calculated concrete volume to cover over-excavation, uneven subgrade, spillage, and short loads. Footings commonly carry a 5–10% waste allowance.
Deformed steel bars cast into concrete to carry tension the concrete cannot. Footings commonly run continuous horizontal bars; size and placement follow the plan and local code.
A short reinforcing bar that ties one concrete element to the next — for example, vertical dowels set in a footing to bond the stem wall poured on top of it.
A groove formed into the top of a footing, usually with a beveled 2x4, that keys the wall pour to the footing and helps resist sliding and water passage at the joint.
How far the footing extends beyond the face of the wall it supports. The IRC requires at least a 2-inch projection on each side, and the projection may not exceed the footing thickness.
A slab poured in one piece with a thickened, reinforced edge that acts as the footing. Common in warm climates without deep frost, it eliminates the separate footing-and-stem-wall pour.
Excavation wider or deeper than the footing itself, which increases the concrete volume actually placed. Over-dig is a main reason real yardage exceeds the theoretical calculation — hence the waste factor.
To strike off wet concrete level with the tops of the forms using a straightedge. Footings are screeded to a consistent top elevation so the wall or piers above start level.
A field measure of concrete’s wetness and workability, in inches, from a standard cone test. Footing mixes are typically ordered at a moderate slump so concrete flows into forms without segregating.
Pounds per square inch of compressive strength concrete is designed to reach, commonly 2,500–4,000 PSI for residential footings. The mix is specified by its 28-day strength.
Keeping fresh concrete moist and at a workable temperature so it gains strength. Footings gain most strength in the first days and reach design strength at about 28 days.
A visible seam where fresh concrete is placed against concrete that has already begun to set, creating a weaker plane. Continuous footing pours are planned to avoid unplanned cold joints.
Voids on a concrete surface where mortar failed to fill around the aggregate, usually from poor consolidation. In footings it signals the mix was not vibrated or rodded enough during placement.
Turn these terms into numbers with the free tools: footing volume and bags on the concrete footing calculator, run totals on the linear feet of footing calculator, and code-driven sizes on the footing size chart. New to the trade vocabulary of length? Start with how to measure linear feet.
FootingTakeoff reads a footing plan and returns total linear feet, pad count, and an invoice at your rates — automatically.