Footings — technical guide
Pad Footing vs Strip Footing Melbourne — When Each Wins for Reactive Clay
Pad footing vs strip footing is not really a choice on most Melbourne sites — it is a decision the structural drawings make for you based on the load path, the site classification under AS 2870, and the structural elements sitting above the footing. But how those two footing types are set out, tied together, and detailed for Melbourne’s reactive clay is where builders and engineers earn the value. This is a technical comparison of pad vs strip footings on Melbourne sites, when each type wins, what site classification does to the call, and the cost implications for builders.
The load-path question — what each footing actually does
A pad footing is a discrete square or rectangular pad of reinforced concrete that spreads a concentrated point load from a column, post or pier into the ground. A strip footing is a continuous linear beam of reinforced concrete that spreads a continuous line load from a wall — masonry, framed, or boundary — into the ground. Both do the same job at the physical interface with the soil: distribute the structural load over an area large enough that the bearing pressure stays under the safe bearing capacity of the founding stratum. What differs is the shape of the load coming down.
On a Melbourne site, the choice between pad footing vs strip footing comes from the structure. A single-storey framed house with continuous perimeter walls uses strip footings under the walls with an integrated slab, giving a stiffened raft that handles reactive clay movement well. A steel portal frame commercial shed uses pad footings under each column with a slab poured separately. A townhouse project might use both — strip footings under masonry party walls, pad footings under the steel portal at the driveway crossing. The structural drawings dictate which footing sits under which element, and the site classification dictates how deep and how heavily reinforced each one has to be.
Why this matters
A footing designed for the wrong load shape is a footing that will crack. Pad footings under a continuous wall load produce differential settlement between pads. Strip footings under isolated column loads waste concrete and reinforcement. Getting the footing type matched to the load path is the base decision that everything else builds on.
Melbourne reactive clay — what AS 2870 site classification changes
Melbourne sits on some of the most reactive clay soils in Australia. The city’s south-east, the outer south, and much of the north-east are classified H1 or H2 — highly reactive clay that swells by 30 to 40mm or more between winter wet and summer dry. Parts of Cranbourne, Officer, Casey and the outer south sit on Class E soils — extremely reactive — where seasonal movement can exceed 60mm. That movement drives footing design more than any other factor on a Melbourne residential build.
AS 2870 (Residential slabs and footings) classifies sites into five reactive classes plus P (problem soils). Each class carries a design ground movement in millimetres, which drives the required footing stiffness, depth, and reinforcement. A footing designed for Class M performs correctly on M but is inadequate on H2. A footing designed for H2 is over-specified on M — costing more but not failing. Getting the site classification right is prerequisite to getting the footing right, and it is done by a geotechnical report or a professional inspection before the drawings are stamped.
| Class | Reactivity | Design movement | Typical Melbourne areas |
|---|---|---|---|
| A | Non-reactive (sand, rock) | 0mm | Bayside sand belts, rocky outcrops |
| S | Slightly reactive | Up to 20mm | Inner-city stable ground |
| M | Moderately reactive | 20–40mm | Much of metropolitan Melbourne |
| H1 | Highly reactive | 40–60mm | North, north-east, south-east clay belts |
| H2 | Highly reactive (upper) | 60–75mm | Outer south-east, growth corridors |
| E | Extremely reactive | Over 75mm | Casey, Cardinia, parts of Whittlesea |
| P | Problem site — special design | Case by case | Fill, uncontrolled fill, mine subsidence |
Ground movement of 40mm at one corner of a house and 10mm at another means a 30mm differential across the structure. If the footing is not stiff enough to redistribute that load — or the structure above is not detailed to handle it — the walls crack. The footing choice, and its detailing, is what stops that crack appearing in year three of a build.
When pad footings win — and when strip footings do
Pad footings suit isolated point loads. Steel portal frame columns on a commercial shed, timber posts on a residential deck or verandah, isolated piers under a suspended timber floor, columns carrying an intermediate steel beam. The pad is sized to spread that concentrated load over enough area to stay under safe bearing pressure, and reinforced to distribute the load radially through the pad.
Strip footings suit continuous linear loads. Masonry walls on a residential build, framed walls with a roof load, boundary walls, retaining walls, brickwork over openings supported by a footing beam. The strip is sized to spread the continuous load over enough width to stay under safe bearing, and reinforced longitudinally to bridge soft spots and resist ground movement between supports.
- Steel portal frame columns
- Timber posts on decks and verandahs
- Isolated piers under suspended floors
- Columns carrying intermediate beams
- Freestanding structures (carports, sheds)
- Masonry walls (brick, block)
- Framed walls with roof load
- Boundary walls
- Perimeter walls of any residential build
- Load-bearing internal walls
- Townhouse projects with mixed structure
- Commercial with masonry + portal
- Extensions to existing structures
- Multi-level residential with steel
On highly reactive Melbourne clay (H1, H2, E), pad and strip footings are almost never used in isolation for a residential build. The dominant residential footing solution is a stiffened raft slab designed to AS 2870 — an integrated concrete raft with strip footings under the perimeter walls, internal beam runs under load-bearing walls, and thickenings under point loads. The stiffened raft acts as a single structural element that redistributes ground movement across the whole footprint, minimising differential settlement.
Pouring footings on Melbourne’s reactive clay?
Pad footings, strip footings, stiffened raft slabs — engineered to AS 2870, poured by crews who know Melbourne ground.
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Cost implications — the honest comparison
Comparing pad footing cost against strip footing cost as a straight per-unit or per-metre number misses the point. The two footings do different jobs. But builders still ask, so the honest ranges below are indicative for typical Melbourne residential and light commercial builds — always quote off engineered drawings.
All figures indicative and quoted off drawings. On any given Melbourne project the actual cost depends on the site classification, structural drawings, excavation conditions, reinforcement schedule, concrete strength grade, formwork requirement and site access. A stiffened raft on Class H2 with an engineered beam schedule can double the base strip footing rate — and it should, because the structural stiffness it provides is the reason the walls above stay uncracked.
“The stiffened raft came in above our budget line. We asked why. Cinerari walked us through the H2 classification, the beam schedule, and the differential settlement risk on the ground we were building on. It made sense. Two years in, the walls are dead straight and the client is happy. Cheaper wasn’t the right answer on that site.”
— Melbourne builder (project client)
Common Melbourne mistakes on pad and strip footings
Every year we see the same handful of footing mistakes on Melbourne sites. All of them are avoidable. All of them cost more to rectify than they would have to build correctly.
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Site classification skipped. Footing designed off a plan without a soil test or a proper site classification. On reactive clay this is the fastest route to a cracked house. -
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Fill not accounted for. Uncontrolled fill under a footing settles unevenly. The engineered footing then bridges a soft spot it was never designed for. Classification should catch this. Sometimes it does not. -
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Cover to reinforcement wrong. Reo sitting on the ground with 20mm cover corrodes fast, spalls the footing, and reduces structural life. AS 3600 covers this. Site check the reo before pour. -
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Strip footing depth reduced on site. A designed strip footing depth is not a guideline. Reducing depth to save time or concrete produces a footing that cannot handle the design ground movement. The crack shows up in year two. -
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Pad-strip interface poorly tied. Where a pad footing supports a column adjacent to a strip footing carrying a wall, the two must be tied by reinforcement or a beam. Untied, they settle independently and the wall cracks at the interface. -
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Concrete cure abandoned. Reactive clay does not care about a footing that was rushed. Full 28-day cure to design strength is not optional on structural footings.
What to do
- Get a proper site classification under AS 2870 before the footing design is finalised.
- Match the footing type to the load path — pad for point loads, strip for line loads, stiffened raft for residential on reactive clay.
- Follow the engineered drawings exactly on depth, reinforcement schedule, cover, and concrete strength.
- Tie pad-to-strip interfaces properly where they meet.
- Cure the concrete to design strength before loading the footing above.
Pad footing vs strip footing — the summary call
On a Melbourne site, pad footing vs strip footing is a question the structural drawings answer for you. Pad for point loads, strip for line loads. The interesting question is not which type, but how the two are detailed, tied, and integrated to handle Melbourne’s reactive clay. Site classification under AS 2870 drives the depth, reinforcement, and stiffness. Reactive clay makes stiffened raft slabs the dominant residential footing solution on H1 and above. Portal-frame commercial builds keep pad footings alive on almost every site. The right answer on any given project is the one on the engineered drawings — and the right execution is following them.
For the full footings service scope — including stiffened raft slabs, pad footings, strip footings, edge beams and pier and beam systems on reactive Melbourne clay — see house footings Melbourne. Related: concrete slabs Melbourne for the slab that sits on top, and retaining walls Melbourne for wall footings and boundary structures.
Footings on Melbourne reactive clay — done properly
Cinerari pours to engineered drawings on Class M through E sites across metropolitan Melbourne and the growth corridors.
Get a quote
or call 0400 692 550
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Frequently asked questions
When do you use pad footings instead of strip footings?
Pad footings suit concentrated point loads — columns, posts, portal frame supports, isolated piers. Strip footings suit continuous linear loads — masonry walls, framed walls carrying a roof, boundary walls. On reactive Melbourne clay the site classification and structural drawings will name which footing applies to which element.
What is the difference between pad footing and strip footing?
A pad footing is a discrete square or rectangular concrete base carrying a single column or point load. A strip footing is a continuous linear beam of concrete carrying a wall or line of load. Pad spreads point loads; strip spreads line loads. Both may sit on the same site and same structure.
Which is cheaper — pad or strip footings?
Pad footings are cheaper per unit but only work for point loads. Strip footings cost more in concrete and reinforcement per lineal metre but are unavoidable under continuous walls. The right comparison is not cost — it is which footing the structure actually needs.
What Melbourne site class affects footing choice?
AS 2870 classifies sites A, S, M, H1, H2, E and P. Class M is moderately reactive clay; H1 and H2 highly reactive; E extremely reactive; P problem soils requiring specific engineering. Higher classes push footing design toward stiffer solutions — deeper strip footings, tied pads, stiffened raft slabs, or piled systems.
Can you mix pad and strip footings in one building?
Yes. Most commercial and larger residential Melbourne builds carry pad footings under portal frame columns and strip footings under masonry or framed walls, connected via edge beams and tied reinforcement. The engineered drawings specify the interface details.
What is a stiffened raft slab and when is it used?
A stiffened raft is an integrated concrete raft with beams and thickenings that distribute load and resist differential settlement. It is the dominant residential footing solution on Melbourne Class H1, H2 and E sites, replacing separate pad or strip footings with a single stiffened slab designed to AS 2870.
How deep should footings be on Melbourne reactive clay?
Depth is set by the engineered design against site classification. On Class M, typical residential strip footings sit 500 to 700mm deep. On H2, 700 to 900mm plus edge beam thickenings. On E, deeper and often into a stiffened raft. Never reduce below the drawn depth.
Sources
- Standards Australia — AS 2870 Residential slabs and footings, AS 3600 Concrete structures
- Victorian Building Authority — footing design and building permit guidance
- Engineers Australia — geotechnical practice guidance for reactive soils
- CSIRO — Foundation maintenance and footing performance (BTF 18)
- Master Builders Victoria — structural work and reactive soil guidance
Luke leads Cinerari Contracting, a Melbourne civil and reinforced concrete subcontractor working with builders, developers and civil contractors across metropolitan Melbourne and regional Victoria. Cinerari focuses on structural concrete scopes that matter — footings, slabs, formwork, retaining walls, drainage, and site establishment. Published 6 July 2026 · 11 min read.