Steel Posts / Retaining Wall Advice

150 PFC Dimensions: Full Specification Guide

Because 100PFC and 150PFC are standardised section names under AS/NZS 3679.1, their dimensions and mass per metre are fixed by the standard itself, not by whichever supplier is selling them. This guide sets out the full 150PFC specification, in the same order you'd want it for a materials take-off or a quick sanity check against a drawing.

For the broader comparison between C-channel and H-beam posts on 150 Series walls, see our 150 UC Steel Posts guide, which covers that decision in detail. This article stays focused on the 150PFC dimensions themselves. For the 100PFC equivalent, see our 100 PFC dimensions guide, or the 100PFC vs 150PFC overview if you're still deciding between the two sizes.

Whether you're specifying posts for a DIY sleeper wall, pricing up a trade job, or just double-checking a delivery against what was ordered, the numbers below are the same ones an engineer, certifier or steel estimator would work from — sourced from the section standard itself rather than a single retailer's product listing.

What "150 PFC" Actually Means

In Australian structural steel, a section name like "150PFC" isn't a brand or a model number — it's a designation defined by AS/NZS 3679.1: Hot-rolled bars and sections, published by Standards Australia and Standards New Zealand. The standard sets out the exact geometry — depth, flange width, flange thickness, web thickness, root radius — that every mill producing a genuine 150PFC section has to roll to.

The full commercial designation you'll sometimes see on a delivery docket or mill certificate is 150PFC17.7: the depth in millimetres, the profile code (PFC for Parallel Flange Channel), and the mass per metre in kilograms. Drop the trailing number and you're just naming the profile family; include it and you're specifying the exact section.

This matters practically because it means a 150PFC post from one supplier and a 150PFC post from another should be dimensionally identical, provided both are genuinely rolled to AS/NZS 3679.1 and not a similar-looking but non-standard channel. It's also why a spec sheet for this profile doesn't need to be supplier-specific — the numbers below come from the standard itself, not from a single retailer's catalogue.

150 PFC Dimensions

Standard section properties for 150PFC under AS/NZS 3679.1:

Depth	150.0mm
Flange width	75.0mm
Flange thickness	9.5mm
Web thickness	6.0mm

These figures describe the steel section itself — the raw geometry defined by the standard. They're not a statement about what wall height or load a 150PFC post can safely carry in your ground; that depends on spacing, embedment, soil and surcharge, covered further down.

Each dimension has a practical role beyond the spec sheet:

• Depth (150mm) is the overall height of the channel's cross-section, measured across the web. It's the dimension that primarily governs the post's bending resistance in the direction the wall pushes against it.
• Flange width (75mm) is how far each flange extends from the web. This is the dimension that determines what fits inside the channel — it's directly why the 150 Series pairs with 75mm and 100mm sleepers rather than a different thickness.
• Flange thickness (9.5mm) is the thickness of the horizontal flange plates. Thicker flanges resist local buckling and give bolted brackets and post caps more material to bite into.
• Web thickness (6.0mm) is the thickness of the vertical connecting plate between the two flanges. It contributes to shear capacity and overall section stiffness.

If you're fitting third-party brackets, cleats or post caps to a 150PFC post, these are the dimensions to check against the hardware's stated fit range — particularly flange width and flange thickness, which determine whether a bracket clamps or bolts on cleanly.

Weight Per Metre

150PFC weighs 17.7kg per linear metre. This is the mass figure built into the section's full designation (150PFC17.7) and is useful for freight estimates, manual handling planning, and cross-checking a delivery against what was ordered.

Weight per metre matters for a few practical reasons beyond curiosity. It affects how many posts can go on a single pallet or vehicle load, whether a post can reasonably be handled by one or two people on site, and it's a quick way to sanity-check a delivery — if a supposed 150PFC post feels noticeably lighter than expected for its length, it's worth checking the mill certificate before installing it.

Approximate total weight by stocked length:

Length	Approx. weight
2000mm	35.4kg
2400mm	42.5kg
2800mm	49.6kg
3200mm	56.6kg
3600mm	63.7kg
4000mm	70.8kg
4400mm	77.9kg
4800mm	85.0kg
5200mm	92.0kg
5600mm	99.1kg
5800mm	102.7kg

At the longer end of the range, a single 150PFC post is well over 100kg — worth planning for with mechanical handling or a two- or three-person lift, rather than assuming it can be muscled into position solo.

Sleeper Thickness Compatibility

150PFC belongs to the 150 Series post range, which is built to work with both 75mm and 100mm concrete sleepers. The 75mm flange width is what allows this — there's enough clearance in the channel to accommodate either sleeper thickness, unlike the 100 Series, which is sized more tightly around a single 75–80mm range.

Confirm your sleeper thickness before ordering — posts and sleepers are sold as a matched system, and a mismatch typically shows up as a sleeper that's loose in the channel (too thin) or one that won't seat fully (too thick). Neither is a safe long-term fix, and both are avoidable by checking sleeper specifications against post series before the order goes in.

Standard Lengths Available

Retaining Walls Direct stocks 150PFC in 11 lengths, from 2000mm to 5800mm:

2000mm • 2400mm • 2800mm • 3200mm • 3600mm • 4000mm • 4400mm • 4800mm • 5200mm • 5600mm • 5800mm

Post length isn't the same as wall height. A post needs enough length above ground to carry the full sleeper stack, plus embedment below ground, typically around one-third of total post length as a general starting rule, with a practical minimum of roughly 600mm regardless of how short the exposed wall is. On reactive clay or loose sandy soils, that embedment often needs to increase by around 20–30% beyond the baseline.

Applying that one-third rule to the stocked 150PFC lengths gives a rough starting picture (not a substitute for site-specific advice):

Post length	Approx. embedment (1/3 rule)	Approx. above ground
2000mm	~670mm	~1330mm
3200mm	~1070mm	~2130mm
4000mm	~1330mm	~2670mm
5800mm	~1930mm	~3870mm

Treat this as a rough planning figure only. Confirm exact embedment against the steel post sizing guide or your engineer for your specific soil and wall height — the one-third rule is a starting point, not a design calculation.

Compliance and Galvanising

• Section geometry to AS/NZS 3679.1 (hot-rolled bars and sections)
• Hot-dip galvanised to AS/NZS 4680 — the correct in-ground corrosion protection for Australian conditions
• Supplied to comply with AS 4678-2002 Earth-retaining structures

These three standards cover different things, and it's worth knowing the difference. AS/NZS 3679.1 defines the steel section's geometry and mechanical properties — it's what makes a 150PFC a 150PFC. AS/NZS 4680 governs the hot-dip galvanised coating applied after fabrication, setting out the process and general coating requirements that give the steel its corrosion resistance. AS 4678-2002 sits above both — it's the design standard for earth-retaining structures generally, covering how a wall as a whole (materials, geometry, drainage, and structural design together) is expected to perform.

Meeting all three confirms the material and coating are correct. It doesn't confirm the post is the right size for your specific wall — spacing, embedment and footing still need to be matched to your wall height, soil type and any surcharge load. For walls over 1.0m, near boundaries, on reactive clay, or carrying vehicle or building loads, involve a structural engineer.

How 150PFC Is Made

150PFC is a hot-rolled section, meaning it's formed by passing a heated steel billet through a series of shaped rollers until it takes on the final C-channel profile, rather than being pressed or folded from flat plate at room temperature. Hot rolling is what gives PFC sections their constant flange thickness from web to tip — the parallel-flange geometry that distinguishes them from older taper-flange channel designs and makes them easier to bolt hardware to consistently along the flange.

After rolling, sections destined for retaining wall posts are cut to the stocked lengths, then hot-dip galvanised as a separate process: the steel is cleaned, fluxed, and dipped in molten zinc, which bonds metallurgically to the surface and forms the corrosion-resistant coating specified under AS/NZS 4680. This is a different (and more durable) process than electroplating or spray-applied zinc coatings, which is why hot-dip galvanising specifically is the standard called out for in-ground retaining wall posts rather than a lighter-duty coating.

Checking You've Received a Genuine 150PFC Section

Because the dimensions above come from the standard rather than a specific brand, verifying a delivery is mostly a matter of checking it against the standard rather than against a particular supplier's marketing:

• Check the paperwork. A mill certificate or supplier compliance document should reference AS/NZS 3679.1 for the section and AS/NZS 4680 for the galvanising. If neither is mentioned, ask before installing.
• Spot-check the flange width. A quick tape measure across the flange should read close to 75mm. A section that's noticeably narrower or wider may be a different profile entirely, not a manufacturing tolerance issue.
• Look at the galvanised finish. Genuine hot-dip galvanising has a distinctive crystalline or "spangled" surface texture, quite different from the flatter look of a painted or cold-galvanised (brush-applied) coating.
• Weigh a sample length if in doubt. A one-metre offcut should weigh close to 17.7kg. A significant deviation either way is worth querying with the supplier before the posts go into the ground.

This matters most on engineered or council-approved projects, where the certifier may specifically ask for documentation confirming the section and coating standards used.

Uses Beyond Retaining Wall Posts

While this guide is written for retaining wall end posts, 150PFC is a general-purpose structural section and turns up in plenty of other applications — lintels over openings, light structural framing, fence posts and gate framing, trailer and equipment chassis fabrication, and as a bracing or edge member in general steel fabrication work. The dimensions and weight per metre on this page apply equally in those contexts, since they describe the section itself rather than anything specific to retaining walls.

If you're sourcing 150PFC for a non-retaining-wall application, the same verification principles apply: confirm it's genuinely rolled to AS/NZS 3679.1, and match the galvanising or coating specification to the exposure conditions the section will actually face in service.

How 150PFC Compares to 150UC

It's worth understanding where 150PFC sits relative to the H-beam (UC) options in the same series, without repeating the full buying-decision comparison — that's covered in detail in the 150 UC Steel Posts guide.

The key structural difference is that 150UC is a genuinely symmetrical H-shaped section, offered across three different mass variants for different load requirements, while 150PFC is a single, lighter C-shaped section used specifically for end and start posts rather than the full structural run. At 17.7kg/m, 150PFC is noticeably lighter than any of the 150UC mass options — part of why it's the right choice for a termination point but not a substitute for an H-beam mid-run.

FAQs

Handling and Transport Notes

At close to 103kg for the longest stocked length, transporting and handling 150PFC posts is worth planning for rather than improvising on delivery day. A few points that come up often:

• Vehicle access. Longer lengths (5000mm and up) need a vehicle and unloading area that can accommodate the full post length, not just its weight. Tight suburban driveways and narrow side access can be more of a constraint than the weight itself.
• Manual handling. Posts over roughly 3000mm (around 53kg) are generally a two-person lift at minimum, and longer posts are better moved with a trolley, forklift, or similar mechanical aid rather than carried.
• Site storage. Store posts flat on level bearers rather than leaning upright against a fence or wall, both to avoid a tipping hazard and to keep the galvanised coating from being scuffed against a rough surface before installation.

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