UB150 is shorthand for the 150 mm universal beam family — usually written 150UB14.0 or 150UB18.0. It is one of the most useful small sections for retaining walls: deep enough to be genuinely stiff, light enough for two people to place by hand, and cheap enough that closer post spacing stays economical.
The sizes in the 150UB family
- 150UB14.0 — 150 mm deep, 75 mm flange, 14.0 kg/m
- 150UB18.0 — 155 mm deep, 75 mm flange, 18.0 kg/m
Both have a nominal 75 mm flange, which is the number that matters when you are choosing sleepers: the sleeper has to slide comfortably between the flanges. A 1.8 m 150UB18 post weighs around 32 kg — a two-person lift, no crane, no telehandler.
UB150 versus 150UC30
A 150UB is deeper and narrower than a 150UC; the UC is 150 mm × 150 mm with a much wider flange and, at 30 kg/m, roughly twice the mass. Where a wide flange suits thick concrete sleepers, the UC wins. Where you want stiffness per kilogram and your sleepers are thinner, UB150 is the better buy. Our notes on 150UC steel posts and on 200UB18 posts sit either side of this size and are worth reading together.
Typical retaining wall heights
As a starting point only — a site-specific engineer’s design always overrides this — 150UB posts at 1.2 m centres commonly suit retained heights up to roughly 900 mm to 1.2 m in good soil with no surcharge. Add a driveway, a pool, a slope above the wall or reactive clay and the section will need to step up, or the spacing needs to come in. Above about 1.2 m of retained height we would normally be quoting a 200 series section.
Spacing and footings
- Post centres of 1.2 m are standard and match common sleeper lengths.
- Embedment in the order of two-thirds of retained height into concrete is the usual rule of thumb.
- Footing diameter is typically 300–450 mm for this size of post — confirm against your design.
- Set posts plumb and string-line the flange faces before the concrete goes off; a 5 mm wander is visible over a long wall.
- Backfill with free-draining material and run an ag drain to daylight.
Finish and supply
For buried posts we supply UB150 hot-dip galvanised to AS/NZS 4680, cut to length and drilled if you need it. Doing the drilling before galvanising keeps the coating intact, so send the hole pattern with your order. See the retaining wall steel range for current lengths, and the gallery for finished walls in this height band.
Not sure whether UB150 is enough for your wall? Send the retained height, wall length, sleeper type and what sits behind the wall through the quote and order form or the contact page and we will size it with you. We deliver across Melbourne and regional Victoria, including Gippsland and Traralgon.