The two systems, side by side.
An L-block is a single precast unit shaped like the letter L — a vertical stem and a horizontal base. The retained earth sits on the base, holding the unit in place by its own weight. A cantilever wall is a reinforced concrete wall where the stem is structurally tied to a wide footing. Both work; they win at different jobs.
Speed of install.
L-blocks beat cantilever every time on speed. A two-person crew with a HIAB can land 25–30m (~82-98ft) of L-block in a day on a prepared base. A site-cast cantilever needs formwork, rebar fixing, pour and a multi-day cure. On a 60m (~197ft) run, L-block is usually two days from delivery to handover; cantilever is two to three weeks.
Height range.
| Retained height | L-block | Cantilever | King post |
|---|---|---|---|
| To 1.5m (4'11") | Standard | Overkill | Possible |
| 1.5–3.0m (4'11"–9'10") | Standard | Standard | Standard |
| 3.0–4.0m (9'10"–13'1") | Bespoke L | Standard | Standard |
| Above 4.0m (13'1") | Not suitable | Standard | Standard / contiguous |
Above 4m (13'1"), see our king post guide or talk to us about a contiguous bored pile design.
Surcharge handling.
Cantilever handles vehicle surcharge better than L-block in a push-wall or silage-clamp setting. Where stockpiles, tractors or HGVs run within 1.5m (4'11") of the retained face, the cantilever footing distributes the moment over a wider base. L-blocks can take surcharge but design becomes site-specific quickly.
Foundation and footprint.
L-blocks sit on a prepared granular sub-base or a 100mm (4in) concrete blinding. Cantilever footings are reinforced concrete, typically half the retained height in width. On a 3m (9'10") wall, that's a 1.5m (4'11") footing — a real footprint on a tight yard.
When each one wins.
Pick L-block for silage-clamp walls, aggregate bays, farm push-walls, temporary works, leased-yard splits, and any retained height under 3m (9'10") where speed and relocatability matter. The whole agricultural sector runs on L-block — same units shift between clamp, fertiliser bay and aggregate yard across a season.
Pick cantilever when the wall is permanent, retained height is above 3m (9'10"), vehicle surcharge is significant, or the wall is the boundary of a development with planning conditions on long-term stability. Highway and civils work tilts toward cantilever for the same reasons.
Frequently asked questions
What is the difference between an L-block and a cantilever retaining wall? +
An L-block is a precast L-shaped concrete unit that sits on a prepared base — gravity holds it in place, the heel is loaded by the retained earth itself. A cantilever wall is a single reinforced concrete element (usually cast in-situ or as a large precast) where the stem cantilevers off a fixed footing. L-blocks are quick and relocatable; cantilevers are taller and permanent.
Which is faster to install? +
L-blocks. A two-person crew with a HIAB can land 25–30 metres (~82-98ft) of L-block in a day on a prepared slab. A site-cast cantilever needs formwork, rebar fixing, pour and a multi-day cure before it carries any load. Even precast cantilever sections take longer per metre because of the size and craneage involved.
Which goes higher? +
Cantilever. L-blocks top out at about 3m (9ft10in) of retained earth in standard production; specials run to 4m (13ft1in). Cantilever walls are routine to 5m (16ft5in) and beyond, sized by the structural calc. Above 4m (13ft1in) retained, switch from L-block to a king post system or cantilever.
Can L-blocks be relocated? +
Yes. A standard L-block has lifting anchors cast in. Once the retained earth is cleared away, the unit lifts straight back onto the lorry — useful for temporary works, leased yards, push-walls and silage clamps that may be reconfigured. Cast cantilevers are permanent.
How are foundations compared? +
L-blocks need a level prepared base — typically a granular sub-base or a thin concrete blinding. Cantilever walls need a designed footing with reinforcement, often as wide as half the retained height. The cantilever footprint can dominate the total cost on tight sites.
Not sure which?
Send us your retained height, plan length and what's behind the wall. We'll recommend the system, design it and quote it within 24 hours.