Quick answer: In Melbourne in 2026, a fabricated steel portal frame package typically costs $4,200–$5,500 per tonne ex GST for supply and fabrication, with erection adding roughly $800–$1,500 per tonne depending on site access and craneage. On a per-floor-area basis, the structural steel frame for a standard warehouse works out to about $85–$160 per square metre — the wider the span and the taller the eaves, the closer you get to the top of that range. Below we break down where that money actually goes, with tonnage and cost tables by span and three worked examples.
These figures cover the steel frame only — columns, rafters, purlins, girts, bracing, cleats and bolts. Cladding, concrete slab, roofing and services are separate trades.
Please note: the figures on this page are indicative Melbourne market ranges published as a budgeting guide. They are not a quotation. Actual pricing depends on your engineering drawings, member sizes, connection detailing, surface treatment and site conditions — ask us for a firm price on your drawings.
How portal frame cost is actually quoted
Most Melbourne fabricators (including us) price a portal frame job in one of two ways:
- Per tonne — the industry-standard way to compare fabricators. The rate covers steel supply, workshop fabrication (cutting, drilling, welding, cleat attachment), surface treatment, and usually delivery. Erection is quoted separately or as an add-on rate per tonne.
- Per square metre — useful at feasibility stage before an engineer has sized the members. It is derived from tonnes anyway: floor area × steel intensity (kg/m²) × rate per tonne.
The single biggest driver of your total is not the rate — rates in Melbourne sit in a fairly narrow band — it is the tonnage, and tonnage is driven by span, eave height, wind region, and whether the frame carries a crane.
Tonnage and cost by span (2026 Melbourne rates)
Typical steel intensities for a single-storey industrial portal frame at 7–8 m bay spacing, standard 6 m eaves, no crane, Melbourne wind region:
| Clear span | Typical steel intensity | Steel per 1,000 m² | Supply + fabricate (ex GST) | With erection (ex GST) |
|---|---|---|---|---|
| 12 m | 15–18 kg/m² | 15–18 t | $63,000–$99,000 | $75,000–$126,000 |
| 18 m | 18–22 kg/m² | 18–22 t | $76,000–$121,000 | $90,000–$154,000 |
| 24 m | 22–28 kg/m² | 22–28 t | $92,000–$154,000 | $110,000–$196,000 |
| 30 m | 28–35 kg/m² | 28–35 t | $118,000–$193,000 | $140,000–$245,000 |
Two things jump out of this table. First, going from an 18 m to a 30 m clear span roughly doubles the steel in the roof structure — clear span is expensive, and if your racking layout allows an internal column line, it is the cheapest structural decision you can make. Second, the per-tonne rate barely changes with span; what changes is how many tonnes you are buying.
At 8 Star we fabricate portal rafters and columns up to 13.5 m in a single pass and handle sections up to 800 × 300 mm H-beams and 22 mm plate in-house, which is why long-span frames are a core part of our workload rather than an exception. See our heavy-duty and long-span fabrication capabilities for the full equipment list.
Where the money goes: cost breakdown of a portal frame package
For a typical mid-size job, expect the package to split roughly like this:
| Component | Share of package | Notes |
|---|---|---|
| Raw steel supply | 35–45% | UB/UC sections, PFC, plate; moves with mill pricing |
| Fabrication labour | 25–35% | Cutting, drilling, welding to AS/NZS 1554.1, cleats, QA |
| Surface treatment | 8–15% | Shop primer at the low end; hot-dip galvanising to AS/NZS 4680 at the top |
| Transport | 3–6% | Over-length loads (rafters over 12 m) may need permits |
| Erection & craneage | 15–25% of total | Site access, working at height, crane size drive this |
| Bolts, purlins & bracing | 5–10% | Often underestimated at feasibility stage |
Galvanising vs paint is the most common variable clients ask about: hot-dip galvanising typically adds $350–$550 per tonne over a standard shop primer, but for warehouses near the bay, food premises, or any structure you never want to repaint, it usually pays for itself.
Three worked examples
1. Small workshop — 500 m², 15 m span, 5.4 m eaves, no crane. Steel intensity around 16–18 kg/m² gives 8–9 tonnes. Supply and fabricate: $34,000–$50,000 ex GST. Erected: roughly $41,000–$62,000. Frames this size are often over-quoted by big fabricators because they sit below their efficient batch size — worth getting a workshop like ours to price it directly.
2. Mid-size warehouse — 1,500 m², 24 m clear span, 6.8 m eaves. Steel intensity around 24–27 kg/m² gives 36–40 tonnes. Supply and fabricate: $151,000–$220,000 ex GST. Erected: $180,000–$280,000. Typical fabrication lead time in our workshop for a package this size is 4–6 weeks from approved shop drawings.
3. Large distribution shed — 3,000 m², 30 m clear span, 8 m eaves, provision for a 5 t crane on one bay. Steel intensity around 30–34 kg/m² plus crane corbels and stiffened columns gives 90–105 tonnes. Supply and fabricate: $380,000–$580,000 ex GST. Erected: $450,000–$700,000. At this scale, member size (we handle up to 800 × 300 mm H-beams) and documented QA under an AS/NZS 5131 CC2-aligned process are what separate fabricators — see what our CC2 process covers.
The design decisions that quietly add tonnes
- Clear span vs internal columns. One internal column line on a 30 m building can cut roof steel by 25–35%. If your forklift aisles allow it, take the column.
- Eave height. Every extra metre of eave height adds column steel and pushes up wind loads on the whole frame. Going from 6 m to 8 m eaves typically adds 8–15% to tonnage.
- Crane beams. A 5–10 t overhead crane does not just add the runway beams — it stiffens the columns, upsizes the footings and tightens deflection limits. Budget 15–25% extra steel on crane bays.
- Fire and durability requirements. Intumescent coating or heavier galvanising specs can add more than the difference between two fabricators’ quotes. Lock the spec before you compare prices.
- Repetition. Ten identical frames fabricate cheaper per tonne than seven different ones. Standardise bays wherever the layout allows.
Steel portal frame vs precast concrete
For single-storey industrial buildings in Melbourne, steel portal frames usually win below roughly 35 m spans on speed and total cost: the frame is fabricated off-site while the slab cures, erection is measured in days, and future modifications (new openings, mezzanines, crane retrofits) are straightforward. Precast panels are commonly used for the walls of a steel-framed warehouse — the hybrid is the Melbourne default. Full precast structural frames only tend to compete where fire ratings between tenancies drive the design. If you are still comparing options, our structural steel fabrication service page sets out what we cover end to end.
FAQ
How much does a steel portal frame cost per tonne in Melbourne in 2026?
Typically $4,200–$5,500 per tonne ex GST for supply and fabrication, plus $800–$1,500 per tonne for erection. Complex connections, crane provisions and hot-dip galvanising push jobs toward the top of the range.
How much steel does a warehouse frame need per square metre?
Around 15–18 kg/m² for spans up to 12 m, rising to 28–35 kg/m² for 30 m clear spans at standard eave heights. Cranes, high eaves and heavy wind exposure add more.
What does a portal frame for a 20 m × 25 m shed cost?
A 500 m² building at around 15–18 m span usually lands between $34,000 and $50,000 ex GST for the fabricated steel package, before erection.
Does the price include erection?
Not by default. Most Melbourne fabricators quote supply-and-fabricate first; erection is priced once site access, crane requirements and program are known. Always confirm which basis a quote is on before comparing.
How long does fabrication take?
From approved shop drawings: roughly 2–3 weeks for a small workshop frame, 4–6 weeks for a 30–40 tonne warehouse package, longer for crane buildings or long-lead sections.
Is galvanising worth it on a portal frame?
For coastal exposure, food or wash-down environments, or any building you do not want to repaint in 15 years — yes. Expect $350–$550 per tonne over shop primer.
Can you fabricate long-span rafters in one piece?
We fabricate up to 13.5 m in a single pass, which reduces splices on 24–30 m span rafters. Fewer splices means less site bolting and faster erection.
Do I need AS/NZS 5131 compliance for a warehouse?
Most commercial and industrial structures in Victoria fall under Construction Category 2 (CC2). We execute fabrication under a CC2-aligned process with documented hold points, traceability and weld inspection — ask us for the compliance documentation list with your quote.
Get a real number, not a range
Send us your architectural or engineering drawings and we will price your portal frame package — supply, fabrication and erection — from our Dandenong South workshop. Request a quote.