Glossary

Concrete footing and takeoff terms

Plain definitions of the words that show up on footing plans, in takeoffs, and on invoices — written for footing subs and estimators, not engineers. Each term is defined in one or two sentences you can quote.

Footing types

Footing: A footing is the widened concrete base that spreads a structure’s load onto the soil so the ground can carry it without settling. It sits at the bottom of the foundation, below the wall or column it supports, and is sized so the pressure on the soil stays within what the soil can bear.
Strip footing (continuous footing): A strip footing is a continuous concrete footing that runs beneath a load-bearing wall, spreading the wall’s line load along its length. It is the footing type measured in linear feet on a takeoff, and it is the most common footing on residential foundation plans.
Spread footing: A spread footing is an isolated footing that spreads a single concentrated load — usually from a column or post — over the soil. Because it carries a point load rather than a line load, a spread footing is counted as a unit, not measured in linear feet.
Pad footing: A pad footing is an isolated, usually square or rectangular footing under a post or column. Interior pad footings carry the posts under a main beam; they are counted individually and typically billed at a flat rate per pad rather than by length.
Trench footing: A trench footing is a footing poured into a dug trench, often filling most of the trench depth with concrete so the footing and the foundation wall below grade are effectively one element. It is common on lighter residential and outbuilding work where deep hand-forming is not warranted.
Grade beam: A grade beam is a reinforced concrete beam that spans between piers or pads at or near ground level, carrying wall loads across the gaps between point supports. It is measured in linear feet like a strip footing, but it bridges soft ground rather than bearing continuously on it.
Stepped footing: A stepped footing is a strip footing that changes elevation in steps to follow sloping ground while keeping each section level and below frost. Each horizontal run bears at a different depth, connected by short vertical steps, so the footing stays continuous across a grade change.

Piers and pads

Pier footing: A pier footing is a vertical concrete column that carries a point load down to firm soil or below the frost line, usually resting on a widened base at the bottom. Piers support decks, porches, fences, and pier-and-beam foundations, and are counted as units on a takeoff.
Bored (drilled) pier: A bored pier, also called a drilled pier, is a straight-sided hole augered into the ground and filled with concrete, carrying load through end bearing and side friction. It is the cast-in-place alternative to a driven pile for structural point loads.
Belled pier: A belled pier is a bored pier with a flared, cone-shaped base cut wider than the shaft by a belling bucket. The bell increases the bearing area at the bottom, letting the pier carry a heavier load or bear on weaker soil without a separate spread footing.
Sonotube: A Sonotube is a waxed cardboard forming tube used to cast a round concrete pier. The tube is only a form and has no structural value on its own; the load is carried by the concrete column inside it and the footing base beneath it.
Pile cap: A pile cap is a thick concrete block that ties several driven piles together and distributes a structure’s load into them. It belongs to deep-foundation work and is rarely seen on standard residential footing jobs.
Point load: A point load is a concentrated load applied at a single spot, such as a post or column bearing on a foundation. Point loads are carried by pads and piers rather than strip footings, because they need an isolated base sized to spread that one load over the soil.

Soil, depth, and code

Frost line (frost depth): The frost line is the maximum depth to which the ground freezes in a given locality, and footings must bear below it so freeze-thaw cannot lift them. Frost depth ranges from near zero in the far south to four feet or more in the north, and is set by the local building department.
Frost heave: Frost heave is the upward movement of soil when water in it freezes and expands. A footing placed within the freezing zone can be lifted by frost heave and dropped when it thaws, which is why footings are set below the frost line.
Bearing capacity: Bearing capacity is the maximum pressure the soil can safely support without excessive settlement, expressed as load per unit area. Footing width is sized so the load spread over the footing stays within the soil’s bearing capacity.
Undisturbed soil: Undisturbed soil is native ground that has not been excavated, filled, or loosened, and it is what a footing must bear on. Footings placed on backfill or disturbed ground can settle unevenly, so the excavation is taken down to undisturbed soil of adequate bearing.
Slab-on-grade: A slab-on-grade is a concrete floor poured directly on prepared ground, often thickened at the edges or over a perimeter footing. It is an alternative to a footing-and-foundation-wall crawl space or basement, common in warm climates with shallow frost.

Reinforcing

Rebar: Rebar is deformed steel reinforcing bar cast into concrete to carry tension the concrete cannot. In footings, longitudinal rebar runs the length of the footing to bridge soft spots and control cracking; residential footing rebar is often decided on site rather than shown on the plan.
Dowel: A dowel is a short length of rebar that ties one concrete pour to the next, such as vertical bars left projecting from a footing to bond the foundation wall poured on top of it. Dowels transfer load and keep the two elements acting together.
Keyway: A keyway is a groove formed into the top of a footing so the foundation wall poured on top interlocks with it, resisting sliding and helping seal against water. It is formed by pressing a tapered strip into the wet footing concrete and removing it after set.
Lap splice: A lap splice is the overlap where two lengths of rebar run side by side and are tied together so load transfers between them. Footing rebar is spliced by lapping bars a specified distance rather than by welding, and the lap length adds to the total bar quantity.

Takeoff and estimating

Takeoff: A takeoff is the process of measuring quantities off a set of plans to price or order the work. A footing takeoff measures every footing run to produce total linear feet plus the count of pads and piers, which is what a footing subcontractor bills from.
Linear foot (LF): A linear foot is one foot measured along a length, and it is the unit continuous footings are measured and billed in. A footing sub’s primary quantity is total linear feet of footing; pads and piers are counted separately as units.
Cross-section: A footing’s cross-section is its width times its thickness — the shape you would see if you sliced across it. Cross-section times length gives the concrete volume, so the cross-section, not the depth of burial, is what drives cubic yards on a takeoff.
Cubic yard: A cubic yard is 27 cubic feet, and it is the unit ready-mix concrete is ordered and sold in. Footing concrete volume is calculated in cubic feet from the cross-section and length, then divided by 27 to order in cubic yards.
Unit price: A unit price is a rate charged per unit of work — per linear foot of footing, or a flat rate per pad or pier. Footing subs bill from unit prices so an estimate is the measured quantity multiplied by the agreed rate for each item.
Bid: A bid is a priced offer to do a defined scope of work. A footing bid is built from the takeoff quantities — linear feet, pad and pier counts — multiplied by the sub’s unit prices, plus any allowances for access, rebar, and site conditions.
Ready-mix: Ready-mix is concrete batched at a plant and delivered by truck, ordered by the cubic yard for a scheduled pour. Footing pours are almost always ready-mix, and the order quantity comes from the takeoff volume plus an allowance for over-excavation and waste.
Over-excavation: Over-excavation is soil dug beyond the neat footing dimensions — from uneven trench bottoms, sloughing sides, or intentional over-dig — that fills with extra concrete on an unformed pour. It is why a concrete order carries a waste allowance above the calculated footing volume.

Reading plans

Dimension string: A dimension string is a run of linked measurements along a plan edge that gives the spacing between grid lines, walls, and openings. Footing lengths are read from dimension strings, and cross-checking a string’s parts against its stated total catches plan errors before they reach a bid.
Footing schedule: A footing schedule is a table on the structural drawings listing each footing type with its width, thickness, and reinforcing. It is the authoritative source for footing sizes on a takeoff — you read the size from the schedule rather than scaling it off the drawing.
Pad schedule: A pad schedule is a table listing each pad or pier type with its plan dimensions and depth. It tells you the size and count of the isolated footings, which are billed as units, and it is where you confirm a pad’s dimensions instead of assuming them.
Scale (calibration): Scale is the ratio between plan distance and real distance, and calibration is confirming that ratio before measuring. A takeoff scaled to the wrong calibration multiplies every length by the same error, so the scale is verified against a known dimension first.
Formwork: Formwork, or forms, are the temporary molds that shape and contain wet concrete until it sets. Footings are often poured neat against the trench soil without forms, while raised or precise footings and piers are formed; forming is labor that a footing rate accounts for.
Screed: To screed is to strike off the top of freshly placed concrete to a level, even surface using a straight edge. Footings are screeded to grade so the foundation wall or posts above bear on a flat, correctly-elevated top.

Where these terms come from

Every term here is defined the way it is used on residential and light-commercial footing work. For the how-to behind them, see the footing takeoff guide, footing types, pier footings, footing depth and frost line, and rebar in footings. For the arithmetic, the free footing calculators at footingcalc.com convert these quantities directly.

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