What it is called, by market
One concept, four markets. Where a name means something else locally, the card says so rather than leaving you to find out on site.
United Kingdom
Same word, different thingfoundation
also strip foundation, trench fill, footing, raft, pad foundation
FOOTING is used loosely for the whole foundation. The named types are the distinction that matters: a strip is a thin band with masonry built off it, trench fill is concrete nearly to ground level.
Australia
Close, not identicalfooting
also strip footing, pad footing, waffle raft, stiffened raft, bored pier
FOOTING is the standard term and the site classification by soil reactivity drives the design, which is why waffle rafts and stiffened slabs are common where British practice would dig a trench.
United Statesyours
Same word, different thingfooting
also spread footing, foundation wall, stem wall, grade beam, frost footing
The FOOTING is the widened base only; the FOUNDATION or STEM WALL is the separate wall built on it. Two elements, two pours, two drawings — where British practice often has one.
Canada
Same word, different thingfooting
also spread footing, foundation wall, frost wall, grade beam
As the United States, with frost depth governing so strongly that a foundation wall is often a full basement wall simply because the footing has to be that deep anyway.
The governing standard, by market
United Kingdom
Approved Document A / BS 8004
Structure, and the code of practice for foundations including bearing pressures and minimum depths.
United States
IRC Chapter 4 / ACI 332
Prescriptive footing widths and frost depth requirements for residential work, and residential concrete construction.
Calculators for this
Each works in either measurement system, and the terminology on the page follows whichever market you have selected.
Frequently asked questions
- Is a footing the same thing as a foundation?
- Not in North America, and the difference is two separate concrete elements. There, the FOOTING is the widened pad or strip at the bottom that spreads the load over enough soil, and the FOUNDATION WALL or STEM WALL is the wall built on top of it carrying the structure up to floor level. They are poured separately, reinforced separately, and drawn separately, and a quantity for one is not a quantity for the other. British practice uses the word foundation for the whole assembly and often does not have two elements at all, because trench fill pours concrete nearly to ground level in one operation. So a bill of quantities crossing markets has to establish which elements are being priced before any volume is meaningful.
- Why is a trench-fill foundation usually cheaper than a strip?
- Because it trades a cheap material for expensive labour, and on most sites that trade wins. A traditional strip puts a few hundred millimetres of concrete in the bottom of the trench and then a bricklayer builds masonry up from it to ground level, working down a hole — which is slow, needs the trench wide enough to work in, needs the trench held open and safe while they do it, and needs the excavation battered or supported. Trench fill digs a narrower trench and fills almost all of it with concrete in one pour, so the extra concrete replaces days of below-ground bricklaying and a wider excavation. It is more concrete and less of everything else. The strip comes back into its own where concrete is expensive, where the dig is very deep, or where the trench cannot be kept stable long enough to pour it full.
- What sets the depth of a foundation?
- Whatever moves the ground, and which of those governs is regional. In cold climates it is FROST: the base must sit below the depth to which the ground freezes, because water expanding as it freezes lifts anything above it, and that depth is prescribed locally and can exceed a metre. In shrinkable clay it is MOISTURE: clay swells when wet and shrinks when dry, the active zone extends deeper than frost ever does, and nearby trees make it worse by drawing water out, so depths of a metre and often far more are normal and a removed tree can cause heave for years afterwards. Elsewhere it is simply reaching soil that can carry the pressure. This is why a foundation detail cannot be copied between regions: the same house on the same load needs a different depth for a reason that has nothing to do with the house.