Tiny House Footings in Victoria: Movable Dwellings, Class 1a Builds & Concrete-Free Piles

Short answer: a tiny house is either a movable dwelling on wheels or a Class 1a fixed dwelling on land, and the two have very different footing answers in Victoria. Movable tiny houses need an engineered support set, not a stack of timber sleepers under the chassis. Fixed tiny homes need engineered footings under each bearer support, designed to AS 2870. On almost every Victorian block the cheapest and most flexible answer is the same: one concrete-free helical screw pile per bearer support — un-screwable and re-usable if the tiny house is ever relocated.

The longer answer covers the legal distinction Victorian councils actually apply, why tiny houses are deceptively heavy once you load them with off-grid batteries and water, what changes on a sloping or BAL-rated rural block, and why the screw-pile workflow suits the kind of regional Victorian sites where most tiny houses are actually parked. This guide is written for Melbourne metro, Geelong, Ballarat, Bendigo, the Mornington Peninsula and Gippsland.

The Two Tiny House Categories Victorian Councils Apply

The marketing literature treats "tiny house" as a single thing. The building surveyor doesn't. Every Victorian tiny house falls into one of two regulatory boxes, and the box determines the footing design more than anything else:

• Tiny House On Wheels (THOW). Built on a road-registered trailer chassis, generally 2.5 m wide and 6 to 9 m long. Treated as a movable dwelling under the Residential Tenancies Act and the Caravan Park regulations rather than a Class 1a building, provided it remains capable of being moved within 24 hours and is not permanently connected to mains services. Many Victorian councils will accept a THOW parked on a host property for personal use; some require a permit to occupy long-term. The footing question is not "do I need a permit" but "what do I sit it on so it doesn't bog into Class H1 clay through the winter."
• Tiny House On Foundations (THOF). Built directly onto a permanent footing set, generally 25 to 50 square metres of internal floor, with mains services and full fit-out. This is a Class 1a building under Volume 2 of the National Construction Code. It needs a building permit, engineered footings signed to AS 2870, often a planning permit in rural and overlay-affected zones, and a final occupancy permit. From a footing perspective it is treated exactly like a small Class 1a granny flat — see our granny flat footings guide for the parallel detail.

The line between the two is drawn on three things: fixity (can it actually be moved?), services (is it on mains or off-grid?) and occupancy (is someone living there full-time?). A THOW that has lived in the same paddock for five years, plumbed in, hard-wired to mains, with decking built around it, is the case where councils most often rule "this is a Class 1a build, you need a permit retroactively." Get the classification straight up front; the footing design follows from it.

Why Tiny House Footings Are a Point-Load Problem

A tiny house, on or off wheels, concentrates its load onto a small number of supports. The trailer chassis is usually a pair of steel C-section rails with cross-members and a coupling tongue; a fixed tiny house is built on timber bearers spanning between piles. Either way, the load reaches the ground through point supports, not a continuous slab.

The numbers, in rough Victorian terms:

• A 6 m tiny house weighs 3.5 to 4.5 tonnes fitted out for off-grid living (cladding, insulation, kitchen, bathroom, loft, batteries, water tanks).
• A 7.5 m tiny house lands at 4.5 to 6 tonnes.
• A 9 m tiny house lands at 6 to 8 tonnes.
• Designed on four corner supports plus two intermediates, each support transfers 8 to 15 kN to the ground under serviceability load — significantly higher under design wind uplift on an exposed coastal or ridge site.
• A loaded off-grid tiny house with a full 2,000 L rainwater tank and a 10 kWh battery wall can add another 2.5 tonnes of dead load over a small area, all of which lands on the rear bearer pair.

Those numbers are deceptively large for a structure that looks like a "cabin on a trailer." A 200 mm-square paver, a stack of timber sleepers, or four supermarket-grade jack stands cannot resist that load on Victorian reactive clay without settling unevenly through the first wet winter. The doors stop closing, the loft tilts toward the heavy end, and the chassis takes a permanent twist. Most tiny house "the floor went out" complaints in Victoria are a footing problem, not a build problem.

The Victorian Permit Picture for Tiny Houses

A habitable tiny house in Victoria touches three sets of rules: the Building Regulations 2018, the Planning and Environment Act via local council planning schemes, and the Residential Tenancies Act if it is rented out. In practice, the footing-relevant points are:

• A fixed (THOF) tiny house requires a building permit from a registered building surveyor, an engineer's footing design signed to AS 2870 and AS 1170, and a final occupancy permit before it can be lived in.
• A movable (THOW) tiny house generally does not require a building permit if it remains genuinely movable, but most councils still require it to be parked behind appropriate boundary setbacks, with adequate effluent and stormwater management, and not used as a long-term primary dwelling without a permit.
• A planning permit is often required in rural zones, on lots with a Bushfire Management Overlay (BMO), Heritage Overlay (HO), Significant Landscape Overlay (SLO) or Environmental Significance Overlay (ESO), and frequently for second dwellings on suburban lots regardless of category.
• If the site is bushfire-prone, a BAL assessment drives both the cladding and the sub-floor detail.
• A short-stay or holiday-rental tiny house has additional planning permit triggers and is increasingly being flagged by councils in tourism corridors like the Mornington Peninsula, Great Ocean Road and Gippsland coast.

The most expensive mistake in Victorian tiny house builds isn't the footings — it's misreading the category and finding out after the fact that the council considers it a Class 1a build that has been occupied without a permit. The footing engineering is usually the cheapest part of the permit pack, and getting it certified up front gives the building surveyor confidence in the rest of the build. For the broader regulatory picture across all footing types, see our Victorian footing regulations guide.

Footing Options for a Tiny House

The headline pattern: one engineered support per bearer point, with a steel bearing cap or chassis bracket sized to the tiny house, beats every alternative on a Victorian site. The pile resists the point load through soil friction and helix bearing; the cap transfers that capacity cleanly into the chassis rail or timber bearer; the tiny house sits level the day the piles go in and stays that way.

Sloping Blocks: Where Tiny House Footings Earn Their Keep

The most common Victorian tiny house site by a wide margin is a regional or peri-urban block with a fall — a back paddock in the Macedon Ranges, a Gippsland hobby farm, a Mornington Peninsula coastal lot, a Yarra Valley vineyard corner. Tiny houses are popular on these sites precisely because they install fast and don't need a full earthworks crew on the ground.

Concrete-free piles are designed for exactly this. Each pile is screwed to engineer-specified torque or refusal, the bearing head is welded or cut to a different cut-off height under each bearer, and the four to eight heads finish on a single level plane. A 400 to 800 mm fall across the length of a 9 m tiny house — which would otherwise force a tall stepped concrete pier, retained fill, or a cut-and-fill platform with associated drainage — is absorbed by the cut-offs. The tiny house arrives on a tilt-tray, the lift contractor lowers it onto the heads, and the chassis is dead level on day one.

A bored-pier build on the same slope is much more expensive: each pier needs over-height formwork, the spoil has to be carted up or down the fall, the concrete truck often can't reach the back piers and the pump distance adds cost, and the contractor has to come back twice. We cover the general sloping-block footing problem in more depth in our footings for sloping blocks guide.

BAL-Rated and Bushfire-Prone Sites

A large share of Victorian tiny houses end up on blocks with a Bushfire Management Overlay — the Dandenongs, Otways, Macedon Ranges, Yarra Valley, Strzelecki Ranges and rural Gippsland are the most common postcodes we see in tiny-house quotes. The BAL rating — from BAL-LOW through BAL-FZ (Flame Zone) — is set on the bushfire attack level assessment and drives a lot of the build detail.

From a footing perspective, BAL ratings influence two things:

1. The sub-floor space cannot harbour embers. A tiny house on piles sits with a ventilated gap between the chassis or bearers and the ground. At BAL-29 and above, that gap needs to be enclosed with non-combustible perimeter skirting (compressed fibre cement, steel sheet, or screened to AS 3959 ember requirements). The piles themselves are steel and BAL-compliant; the skirting is a builder detail rather than a footing detail, but the two have to be coordinated at pile cut-off stage.
2. Vegetation clearance and tree protection. BMO setbacks and council tree-protection zones often overlap. Concrete-free piles install with hand-held drive equipment that can deflect around mature roots; bored piers usually can't be approved within a Tree Protection Zone. See footings near trees for the TPZ detail.

Off-Grid and Remote Regional Tiny Houses

A growing share of Victorian tiny house owners are not on mains water, sewer or power — they're on tank water, composting or worm-farm waste, and solar with battery storage. From a footing perspective that matters in two ways:

• Battery and tank weight. A 10 kWh lithium battery wall is around 90 kg, but a 2,000 L water tank coupled inside or under the deck is 2 tonnes of dead load over a small area. The footing engineer needs to know where it lands.
• Access for install plant. Pile install equipment is mounted on a small mini-excavator or skid-steer and accesses through a 1.5 m gate, down a paddock track, or across pasture without leaving a scar. A concrete truck and pump combination usually can't reach remote tiny house pads, and ready-mix delivery to remote regional Victoria carries a heavy long-haul premium — sometimes 50 % above the metro mix price by the time the truck has driven two hours each way.

The workflow we see most often on a remote regional tiny house:

1. Engineer's setout. Pile positions are surveyed to the chassis rail or bearer centres, typically ±15 mm tolerance.
2. Piles installed and capped. Half a day on site for a 6 to 7.5 m tiny house, full day for a 9 to 12 m build, often the day before the tilt-tray.
3. Tiny house delivered. Tilt-tray reverses to the pad, the operator slides the tiny house off the truck and lands the chassis rails directly onto the bearing heads.
4. Bolt down or strap. Engineer-specified anchor rods or steel strap tie-downs secure the chassis to each pile head.
5. Services and skirting. Water tank connection, solar penetration, decking and perimeter skirting follow over the next week or two.

Choosing the Right BMSA System for Your Tiny House

• SurePile is the default for almost every Victorian tiny house. The helix lets a single pile carry the 8 to 15 kN per-support load on Class M, H1 and H2 reactive clay, fill, and sloping or remote regional sites. Variable cut-off means perfect levelling regardless of ground fall, and the pile is fully un-screwable if the tiny house is later relocated — valuable on land you don't own or on a property with a future development plan.
• RapidStump suits 6 to 7.5 m tiny houses on stiff Class M or better soil where bearing is reached inside 3 m. Common on Melbourne inner-suburb infill blocks where a tiny house is being added behind an existing house as a studio or second dwelling.
• StumpRite is the option to consider for THOW long-term parking. The 120 mm of screw-thread adjustment lets the owner re-level the dwelling seasonally without disturbing the chassis, which suits sites where some long-term reactive-clay movement is expected and engineering risk-tolerated.

For a side-by-side comparison of all three see our RapidStump vs StumpRite vs SurePile breakdown. For the full screw-pile primer, see our screw pile footings Melbourne guide.

Soil & Site Considerations

• Class M reactive clay. The default soil across most of Melbourne's middle-ring suburbs and a wide band of regional towns. Driven steel stumps work for 6 to 7.5 m tiny houses; screw piles are the safer choice for 9 to 12 m builds, especially fully fitted off-grid units.
• Class H1/H2 reactive clay. Common across inner-east Melbourne, bayside, western basalt suburbs and the Bellarine. Shallow piers can be heaved by seasonal moisture; screw piles to 2.5 to 3.5 m bypass the active zone. Critical on a tiny house, because differential heave between front and back supports twists the chassis and pops door alignment within one season.
• Class P (problem) soils. Old farm fill, peat in the Westernport fringe, soft alluvial deposits along the Yarra and Goulburn floodplains, mine subsidence in central Victoria. Tiny house piles on these sites must penetrate to a confirmed bearing layer, which a screw pile does with live torque measurement at install.
• Sandy coastal sites. Mornington Peninsula, Phillip Island, Bellarine, Surf Coast. Loose surface sand on a stiffer base; piles drive through to the bearing layer cleanly and the cap heads sit well above any sand drift line.
• Sloping rural blocks. Tiny house piles are the cheapest correct answer here by a wide margin — see the section above.
• Remote / off-grid access. Pile install equipment accesses through a 1.5 m gate; concrete truck access often can't. This single factor decides most rural tiny house quotes.

Practical Tips for Tiny House Footings

• Get the finished weight in writing from the builder. A 7.5 m tiny house fully fitted is a much heavier number than the trailer-tare quoted at sale. Get the kerb weight including water tanks, batteries, internal joinery, double-glazed openings and any external decking.
• Confirm the chassis rail layout. Most THOW builds have two main C-section rails and several cross-members. The footing setout follows the rail centres, not the visible cladding edge of the build.
• Specify the bearing cap with the pile. The cap has to land cleanly under the chassis rail (THOW) or bearer (THOF), transfer load through bearing not bolt shear, and tolerate ±15 mm setout error. A great pile under a poorly detailed cap will still hold the load — but the tilt-tray contractor will curse you on delivery day.
• Plan tie-down for N3 wind country. Tiny houses on the Mornington Peninsula, Surf Coast, Phillip Island and exposed Macedon ridges are light enough to need engineered tie-down to their footings. Screw piles take a tie-down rod directly through a tapped pile head; bored piers need a starter bar cast in at pour time.
• Pothole services first. Sewer, stormwater, gas, telecommunications and rural water-main runs frequently cross the part of the property where the tiny house is going. A $300 hydro-vac potholing run will save you a $5,000 service repair.
• Mind boundary setbacks and overlays. Most Victorian suburban second-dwelling rules want 1 m to the side boundary and 3 m to the rear; rural-zone setbacks can be much larger. BMO sites trigger 10 m vegetation clearance circles around the dwelling. Confirm before setting out piles.
• If it's a THOW, leave it move-able. The footing detail can be a chassis-clamp bracket rather than a welded cap. That keeps the dwelling genuinely movable, which is the test some councils apply when deciding if a building permit is required.
• Document everything. Get the engineering certificate, pile install torque records, and footing layout on file with the building permit pack (THOF) or in the owner's records (THOW). A future sale, a future planning enforcement, or a future insurance claim will all ask for them.
• Plan deck and entry steps at footing stage. A tiny house chassis sits 350 to 600 mm above ground once piled; some THOFs sit higher. Specify the deck or stair piles at the same time as the dwelling footings so the equipment is mobilised once.

What Do Tiny House Footings Cost in Victoria?

Indicative ranges from recent jobs across Melbourne metro and regional Victoria:

Indicative ranges only. Actual quote depends on access, soil report, slope, BAL rating, wind region and bearing depth. All figures ex-GST as at May 2026.

The headline number to watch: concrete-free piles beat bored piers more decisively on tiny house builds than on almost any other application, because the savings on spoil, concrete delivery, cure time and re-mobilisation all stack up against a relatively small per-support footing budget. On a sloping or remote regional block, concrete-free is routinely 35-50 % cheaper installed and weeks faster to occupancy. On a THOW where future relocatability matters, the concrete-free option also preserves the resale value of the dwelling as a genuinely movable asset.

Tiny Houses vs Granny Flats vs Container Homes

Three closely-related small-dwelling categories often get confused in Victorian footing quotes. The footing answer is genuinely different for each:

• A granny flat is a fixed Class 1a dwelling, typically 40 to 60 sqm, built like a small house with a continuous footing perimeter. Slab or pier-and-bearer.
• A shipping container home is a fixed Class 1a build where the entire load goes through eight corner castings, regardless of internal area. Four to eight engineered piles per container.
• A tiny house is either movable (THOW) or fixed (THOF) and rides on a chassis or bearer pair. Four to eight engineered supports along the rail line, never under a single point.

If you're still deciding between the three, the footing cost difference is usually less than 10 % of total build, but the regulatory and resale picture differs enormously. A tiny house is the most relocatable; a container home the most cyclone-resistant; a granny flat the most planning-friendly for permanent residence.

Frequently Asked Questions

The Bottom Line

A Victorian tiny house is fundamentally a point-load problem, not a slab problem — and the right answer depends almost entirely on whether yours is a movable dwelling on wheels or a fixed Class 1a build on land. Get the category straight with your council, get the finished weight in writing from the builder, then install one engineered concrete-free pile under each chassis-rail or bearer support with a properly detailed bearing cap. The piles finish on a single level plane regardless of slope, the tilt-tray contractor lands the tiny house dead level on day one, and the structure is compliant, certified and ready for occupancy permit or council inspection. Skip the stack of timber sleepers under "temporary" jack stands — it will cost less today and considerably more after the first wet winter on Victorian reactive clay.