Key takeaways
- Strip footings spread a wall or line load continuously along their length, while pad footings concentrate support under a point load such as a column or pier, so the two are selected by the load path and the soil profile rather than by preference.
- On reactive clay sites the footing detail is driven by the expected ground movement and the depth of the zone of influence, which is why the engineer’s specification and the geotechnical report must be read together before excavation.
- Setout errors on strip footings compound along the length of a wall and on pad footings shift the load path, and both are expensive to correct once concrete is placed and the surveyor has left.
- Reinforcement loses its designed capacity if it is bartered down into the trench or laid directly on the ground, so chairs, spacers and cover are the details inspectors check first.
- The inspection that matters most happens before the pour, and a footing that is excavated, reinforced and covered in the same day leaves the certifier and the engineer no opportunity to verify what is in the ground.
Strip footings and pad footings are the two most common shallow footing types on residential work in NSW, and the difference between them is not cosmetic. A strip footing spreads a wall or line load continuously along its length. A pad footing concentrates support under a point load, usually a column, pier or post. The choice between them is settled by the load path, the soil profile and the site conditions, and getting it wrong is expensive because it is discovered after the concrete is in.
The NCC sets the performance framework for footings, but the detail that governs the job comes from the geotechnical report and the structural engineer’s drawings. That is why two houses on the same street can have different footing designs: same suburb, different soil profile, different depth to a competent bearing stratum. The builder’s job is not to redesign the footing but to build what is specified and to know which checks will be made.
This article compares the two footing types against typical NSW soil and site conditions, and focuses on the parts of the work that are most often done wrong: setout, reinforcement placement and the pre-pour condition of the excavation.
Why the soil profile, not the plan, decides the footing type
Residential footings in NSW are designed against the soil profile identified in a geotechnical investigation. That investigation classifies the site and describes the expected ground movement, the depth of the zone of influence and the bearing capacity available at the founding level. The structural engineer then designs the footing to suit.
On a site with relatively stable soil and a shallow bearing stratum, strip footings with a modest bearing width are often adequate for the walls. On a site with reactive clay, the design usually has to deal with movement rather than just bearing pressure, and that can push the footing deeper, make it wider, or change the reinforcement. Pad footings come into their own where the load is concentrated and the structure needs isolated support rather than a continuous line.
The practical point is that a builder cannot infer the footing type from the architectural plan. The footing schedule, the geotechnical report and the structural drawings have to be read together, and any inconsistency between them is a question for the engineer before excavation, not after.
Strip footings: where they suit NSW residential work
Strip footings suit continuous line loads. On a brick veneer or full masonry house they typically run under the external walls, under internal load-bearing walls and under any wall that carries roof or floor load. They are also common under retaining walls, though retaining design is a separate exercise.
The excavation is a trench, and the bearing width is set by the design. In good ground the trench may be relatively shallow; in reactive clay the design may require the footing to extend deeper to get below the zone of influence. The trench must be founded on the specified material, and the base must be clean and undisturbed. A trench that has been left open over a wet weekend, with the base softened and loose spoil in the bottom, is not the same footing the engineer designed.
Reinforcement in a strip footing usually runs longitudinally, with cross bars and starter bars for the wall above. The longitudinal bars resist tension and control cracking; the starter bars tie the footing to the wall. If the bars are bartered down into the trench or laid directly on the ground, the cover is lost and the reinforcement no longer acts where it was designed to act. Chairs and spacers are not optional.
Pad footings: where they suit and what changes on site
Pad footings suit point loads. They appear under columns, piers, posts and steel or timber frames, and under any element that delivers load to a small plan area. They are also common in garage and carport construction where a small number of posts carry the roof.
The excavation is a pit rather than a trench, and the plan dimensions and depth are set by the pad design. The reinforcement is typically a mat or cage with starter bars for the column or pier above. Because the pad is small, the setout is less forgiving: a pad that is out of position shifts the load path and can force a redesign of the column or the connection.
Pad footings are also where the interface between trades shows up. The pad may be poured before the column, and the starter bars have to be positioned so the column reinforcement can be lapped correctly. If the starter bars are set in the wrong place or at the wrong spacing, the fix is usually cutting and drilling, which is slower, weaker and more expensive than getting it right the first time.
Strip footings and pad footings compared
| Strip footings | Pad footings |
|---|---|
| Continuous under walls and line loads, spreading load over a long bearing area | Isolated under columns, piers and point loads, spreading load over a defined plan area |
| Excavated as a trench, usually with a relatively narrow bearing width | Excavated as a pit, with plan dimensions set by the pad design |
| Reinforcement runs longitudinally with cross bars and starter bars for walls | Reinforcement is a mat or cage with starter bars for the column or pier |
| Setout is controlled by the wall centrelines and the building envelope | Setout is controlled by the column grid and the structural grid lines |
| Inspection focuses on trench cleanliness, bearing material and cover | Inspection focuses on pit dimensions, bearing material and cage position |
Setout: the error that compounds
Setout is the first place a footing job goes wrong, and the consequences are different for each footing type. A strip footing set out slightly off line will run the whole length of the wall, and the error compounds with every metre. A pad footing set out slightly off grid will misalign the column above, and the error can propagate through the frame.
On most residential jobs the building envelope and the wall centre lines are set out from the surveyor’s pegs, and the footing setout is taken from those. The person doing the setout needs to work from the approved plans, not from a scaled print or a marker on the ground. Profiles should be checked against the survey, and diagonal checks should confirm the building is square before any trench is opened.
The commercial reality is that setout errors are cheap to fix before excavation and expensive to fix after concrete. Once the footing is poured, correcting a setout error can mean cutting reinforcement, re-forming, re-pouring and re-inspecting, and the cost usually lands on the builder because the setout was the builder’s responsibility. On a project with a tight programme, the delay is often worse than the direct cost.
Reinforcement: the detail inspectors look at first
Reinforcement placement is the detail that most often fails inspection, and it is entirely within the builder’s control. The inspector is not checking whether the reinforcement looks neat; they are checking whether it is the specified size, grade and spacing, whether it is supported at the specified cover, whether laps and cog lengths match the detail, and whether starter bars are positioned for the element above.
Cover is the recurring problem. Reinforcement that is laid on the ground has no cover on the underside, and reinforcement that has been walked on or bartered down has lost cover on top. Both reduce the durability and the structural capacity of the footing. Chairs and spacers should be set out so the reinforcement sits at the specified cover, and they should be checked again immediately before the pour, not just at the start of the day.
Laps and cog lengths are the second recurring problem. The reinforcement detail shows how bars are to be lapped and how they are to be bent, and those dimensions come from the design. A bar that is cut short on site, or a cog that is bent to a different radius, changes the capacity of the connection. If the detail is unclear, the question goes to the engineer before the concrete is ordered.
What inspectors and certifiers actually check before the pour
The pre-pour inspection is the point of no return. Once the concrete is placed, the excavation, the bearing material, the reinforcement and the cover are all hidden. That is why the inspection has to happen before the pour, and why the certifier and the engineer need enough notice to attend.
Inspectors typically check the depth and dimensions of the excavation against the design, the material at the founding level, the cleanliness of the trench or pit, the reinforcement as placed, the cover, the starter bars and the setout. They may also check that the excavation is dry and that there is no standing water or softened material. If any of those items is wrong, the fix is usually a small amount of labour before the pour and a much larger amount of labour after it.
The mistake that costs the most is scheduling the pour before the inspection is confirmed. A footing that is excavated, reinforced and poured in the same day leaves the certifier no opportunity to verify what is in the ground, and the result can be a non-conformance that has to be resolved with the certifier and the engineer after the fact. On a residential job that can hold up the frame and the following trades.
Do not order concrete until the inspection is confirmed and the reinforcement has been checked in place. The cost of a delayed pour is a day. The cost of a failed or missing pre-pour inspection can be a non-conformance, an engineer’s assessment and remedial work, all of which lands on the builder and the programme.
Pre-pour checks on strip and pad footings
- Confirm the excavation has reached the bearing stratum or depth specified by the engineer, and that the material at the base is the expected material.
- Check that the trench or pit is free of loose spoil, roots, ground water and softened material that will not carry the design load.
- Verify the setout against the approved plans, including wall centre lines, column grid lines and the building envelope.
- Confirm reinforcement is the specified size, grade and spacing, and that it is supported on chairs or spacers at the specified cover.
- Check laps, cog lengths, ligatures and starter bars against the reinforcement detail, and that starter bars are positioned for the wall or column above.
- Confirm the concrete is the specified strength and slump, and that the pour sequence will not displace the reinforcement or the formwork.
- Ensure the certifier, engineer and any required inspection have been booked before the concrete is ordered.
Concrete supply, pumping and the pour itself
The concrete mix is specified by the engineer, and the builder’s job is to order what is specified and to check it on delivery. Strength, slump and aggregate size all matter, and the discharge docket should be checked against the specification before the pour starts. If the mix is not what was specified, the concrete should not go into the footing.
Concrete pumping is common on residential footings where the truck cannot reach the trench or the pit. Safe Work Australia publishes guidance on concrete pumping hazards, and the key controls on a residential site are the same as on any other: a competent operator, a stable setup for the pump, exclusion zones around the boom and the delivery line, and clear communication between the pump operator and the crew placing the concrete.
The pour itself should not displace the reinforcement or the formwork. On a strip footing, the concrete should be placed so the reinforcement stays at the specified cover; on a pad footing, the cage should be checked again as the concrete rises. Vibration should be used to consolidate the concrete without moving the reinforcement, and the top of the footing should be finished to the level shown on the drawings.
Working example: a builder in western Sydney
A builder in western Sydney is constructing a single-storey brick veneer house on a site with a reactive clay profile. The geotechnical report identifies the soil and the expected ground movement, and the structural engineer designs strip footings under the external and internal load-bearing walls, with pad footings under the posts supporting the rear pergola and the carport.
The builder sets out from the surveyor’s pegs, checks the diagonals and opens the trenches. The excavation reaches the specified depth, and the base is clean and dry. The reinforcement is delivered and placed, with chairs set at the specified cover and starter bars positioned for the walls. The pad footings are excavated to the specified plan dimensions, and the cages are set with starter bars for the posts.
Before the pour, the builder calls the certifier and the engineer for the pre-pour inspection. The inspector checks the depth and dimensions, the bearing material, the reinforcement, the cover and the starter bars, and confirms the setout against the approved plans. The concrete is ordered to the specified mix, the pump is set up with an exclusion zone, and the pour proceeds. Because the inspection was done first, the footing is signed off without a non-conformance, and the frame can start on programme.
The counterfactual is the same job with the pour booked before the inspection. If the trench is backfilled or the concrete is placed before the certifier attends, the builder has to arrange for the engineer to assess what can be verified and what cannot, and the certifier may require additional evidence before issuing the next certificate. That is the scenario where a footing detail becomes a programme problem.
Documentation, records and the CPD angle
Every footing job generates records that matter later: the geotechnical report, the structural drawings, the reinforcement schedule, the concrete dockets, the pre-pour inspection record and any engineer’s directions. These records are what the certifier relies on, and they are also what protects the builder if a question arises during the defects liability period.
For licensed builders in NSW, understanding how footing design, setout and inspection fit together is part of the knowledge base that continuing professional development is meant to maintain. The PointCPD guide to how NSW builder CPD works explains how the requirements apply, and the course catalogue lists the modules that cover siteworks, concrete and structural fundamentals. Builders who want to refresh their knowledge of safe work procedures can also review the SWMS template for residential builders in NSW, which is relevant to concrete pumping and excavation work.
The technical content of footing work changes slowly, but the standards and the NCC are updated from time to time. The Housing Industry Association summary of the NCC 2025 changes is a useful starting point for what has changed for residential builders, and CCAA publishes technical guidance on concrete practice that is relevant to footing pours. Neither replaces the engineer’s drawings or the geotechnical report on a specific job.
Frequently asked questions
These are the questions builders ask most often about strip and pad footings on NSW residential work.
Questions builders ask
How do I know whether a job needs strip footings or pad footings?
The footing type is set by the structural engineer based on the load path and the geotechnical report. Strip footings suit continuous wall loads, and pad footings suit point loads such as columns and posts. The builder should not substitute one for the other without the engineer’s direction.
What does an inspector check before a footing pour?
Inspectors check the depth and dimensions of the excavation against the design, the bearing material at the founding level, the cleanliness of the trench or pit, the reinforcement as placed, the cover, the starter bars and the setout. They may also check that the excavation is dry and free of softened material.
Why is cover so important in a footing?
Cover protects the reinforcement from moisture and chemicals in the ground and keeps the bars in the position assumed by the design. Reinforcement laid on the ground or bartered down loses cover and does not act where it was designed to act. Chairs and spacers should be checked immediately before the pour.
Can I pour the same day I excavate?
Only if the pre-pour inspection has been completed and the reinforcement has been checked in place. Pouring before inspection leaves the certifier no opportunity to verify the excavation and the reinforcement, and can result in a non-conformance that has to be resolved after the fact.
What records should I keep for footing work?
Keep the geotechnical report, the structural drawings, the reinforcement schedule, the concrete dockets, the pre-pour inspection record and any engineer’s directions. These records support the certifier’s assessment and protect the builder if a question arises later.
Do the NCC changes affect residential footings?
The NCC sets the performance framework, and updates can affect residential construction. Builders should check the current edition and the HIA summary of what has changed, and always work to the engineer’s drawings and the geotechnical report for the specific site.
Sources
- Concrete pumping · Safe Work Australia
- Cement Concrete and Aggregates Australia · CCAA
- National Construction Code 2025: what’s changed for residential builders · Housing Industry Association
Published 21 June 2026. General information for builders, not legal, financial or engineering advice for a specific job. Check current requirements with the relevant regulator or standard before relying on them.
