Cantilever engineering is maximising usable footprints in cities like London

Cantilever engineering systems are designed with contractors, designers, and end users in mind

IF YOU SEE a plot of land sitting empty in a city like London, you know there’s a good reason. More than enough developers have gone on that egg hunt through the streets that the chances of finding a perfect – or even a ‘pretty good’ – plot of land waiting between Hammersmith and Greenwich are about as slim as tissue paper. 

You look at a cramped plot between two Victorian terraces or a sloping embankment near a railway line, and it won’t take long to realise that a standard approach will swallow half the saleable footprint before the foundations even dry. 

In other words, digging wide trenches and pouring heavy gravity walls just to hold back the local clay used to dictate exactly where you could and couldn’t build.

The Old Approach

In the past, regional developers handled these awkward urban gaps by battering the soil back at a gentle angle. That keeps the earth from sliding into the basement, yes, but it also wastes metres of real estate that could otherwise hold valuable square footage. London is cramped enough as it is, and buyers a “cosy embankment” outside the kitchen window isn’t high on a London buyers’ list. 

Structural engineering simply had to start defying gravity to make these plots viable. In a project like the London Wall Place development, engineers had to navigate strict rights to light and historic viewing corridors by suspending massive chunks of the commercial floor space right out into mid-air. Storey-high steel trusses support building sections that cantilever up to 11 metres directly over the adjacent pavement. The structure literally hovers above the thoroughfare.

Precast geometry and fix-free installation

Pouring wet concrete into hand-built timber shuttering at the bottom of a soggy, restricted urban trench is a miserable experience. You need massive working clearance behind the wall, which isn’t something London offers.

Shifting the heavy structural load into offsite precast manufacturing completely bypasses the mud. Precision retaining systems crafted from CBS concrete utilise an integrated L-shaped CLF10GS unit where the toe, stem, heel, and interlocking joints are cast as a single solid piece. Site crews lift the units straight off a flatbed and lock them into place without any drilling, structural fixings, messy grout, or exposure to silica dust.

You then have a strong vertical boundary that borders the property edge. The retained soil sitting directly on top of the heel actually provides the counterweight to anchor the whole system. The earth pins itself down.

Maximising the liveable footprint

When land values in urban centres dictate whether a development turns a profit or bleeds cash, every lost centimetre stings.

You can’t afford to lose a chunk of a residential garden to a chunky gravity retaining wall..

Then again, it also simplifies the logistics on cramped sites where you can barely turn a delivery van around. Factory-controlled self-compacting concrete drops tolerances to fractions of a millimetre, giving architects the clearance to push ground-floor living spaces, lower-level terraces, sunken courtyards, and retaining boundaries directly up against the site limit.