Crane Outrigger Pad (Square)

What crane outrigger pads do

A crane concentrates its whole working weight onto four small outrigger floats. Put that float straight on the ground and the pressure often exceeds what the soil can hold, and the crane leg sinks — the leading cause of mobile-crane tip-overs. Crane outrigger pads — also called crane pads, crane support pads, crane leg pads, or crane foot pads — spread that point load over a larger area so the machine stays level and stable through the lift. The same problem shows up under crane outrigger feet on a boom truck or a concrete pump: an unsupported float finds soft ground fast.

Sizing by ground bearing pressure

The rule is simple: pad area = maximum outrigger load ÷ the ground’s safe bearing pressure. Weaker ground needs a bigger pad, not a thicker one. The same arithmetic sets the size of the smaller crane jack pads used under service trucks and lorry-mounted cranes. Square pads run 18×18 in up to 48×48 in (450–1200 mm) with a vertical working load limit from about 12 t to over 100 t by size, so you can match the pad to the leg load and the soil instead of guessing — the full method is in the crane outrigger pads sizing guide. We stock these crane pads for sale across the full size range, factory-direct.

Why a square pad

The square form puts the most area under the float for a given dimension and gives a stable seat for spreader-beam feet and large float plates — sold by some as spreader pads or composite outrigger pads. Moulded in HDPE or UHMW at 1–4 in thick, these plastic crane pads replace the aluminium outrigger pads and timber packing crews used to stack, and cover everything from backhoe outrigger pads up to mobile crane outrigger pads for the largest crawler cranes; the pad spreads pressure without flexing apart, and a cut-in grip keeps it a one-person carry around the setup.

On site

Mobile crane setup, concrete pump stabilisers, piling rig feet, and outrigger pads for boom truck work — anywhere outriggers land on anything softer than engineered hardstanding. The polymer is non-conductive and will not rot or soak up water, so the pads live on the truck between jobs. For cylindrical MEWP and boom-lift feet, the round outrigger pad seats more neatly.

HDPE vs timber vs steel: material choice

Before crane pads existed as a category, crews packed the outrigger float with stacked timber or slid a plate of steel underneath, and plenty of yards still keep some of each. Set them side by side and the case for HDPE heavy duty outrigger pads is straightforward: timber absorbs water, swells, and rots after a season left on a truck bed, while steel plate does not rot but conducts electricity and corrodes at the welds — both routinely need two people or a hoist to move. A moulded HDPE pad in the same footprint is roughly half the weight of steel and does not take on water like timber, so it stays a one-person lift for the life of the pad.

	HDPE crane pad	Timber	Steel plate
Weight, 24×24 in / 2 in	~14–18 kg, one-person carry	~25–35 kg, heavier once wet	~35–45 kg, often needs a hoist
Water	Will not absorb, rot, or delaminate	Absorbs and swells; rots outdoors within a season or two	Will not absorb, but rusts and pits at welds
Conductivity	Non-conductive	Conducts once wet	Conducts — a hazard near live services
Service life	10+ years, UV- and chemical-resistant	2–4 years outdoors before replacement	Long-lived but corrodes at cut edges and welds
Handling	Moulded grip, one person	Splinters; often a two-person carry	Sharp edges; usually two people or a hoist

That combination — light, non-conductive, and unaffected by standing water — is why plastic outrigger pads have become the default choice for crane and MEWP fleets that used to run timber or plate.

Pad size by crane tonnage class

The load-chart method above is the accurate way to size a pad for a specific lift, but as a starting point for outrigger pads for crane classes commonly on site, here is how the range typically breaks down. Treat it as a first cut, not a substitute for checking the actual outrigger load at your working radius.

Crane class	Typical pad size	Thickness	Vertical WLL
~25 t mobile crane / MEWP	18×18–24×24 in (450–600 mm)	1–2 in	~12–25 t
~50 t mobile crane	24×24–30×30 in (600–750 mm)	2 in	~25–45 t
~100 t mobile crane	30×30–40×40 in (750–1000 mm)	2–3 in	~45–75 t
~250 t crawler / large mobile crane	40×40–48×48 in (1000–1200 mm)	3–4 in	~75–100+ t

Ground conditions move a job between rows faster than tonnage does — a 100 t crane on firm compacted hardstanding may sit comfortably on the pad sized for the row above, while the same crane on soft or wet ground needs the larger pad even though the tonnage has not changed. These figures are for the pad under each individual outrigger foot; a crane that needs a full platform to track or crawl across softer ground, rather than point-loading four feet, is a different product — see our HDPE crane mats.

What size outrigger pads do I need?

Pull the maximum outrigger load from the crane’s load chart at your worst-case working radius, then divide by the ground’s safe bearing pressure to get the pad area — that calculation, not the crane’s rated tonnage alone, is what sizes the pad correctly. As a working range, square crane outrigger pads span 18×18 in up to 48×48 in (450–1200 mm) with a vertical working load limit from about 12 t to over 100+ t by size, covering everything from a spider crane to a large crawler. If the ground is soft, wet, or unknown, round up to the next size rather than trust the low end of the range — an oversized outrigger mat costs little; a leg that settles mid-lift does not.

Care, storage, and inspection

A pad that lives on the truck between jobs still needs a quick check before it goes under a loaded outrigger: look for cracks or gouges that cut into the load-bearing thickness, check the moulded grip has not torn away, and confirm the surface is free of mud or grease that could let the float skate sideways during setup. HDPE will not rot or corrode in storage, so pads stacked flat in a yard or racked upright in a truck body need no more than an occasional wipe-down — no oiling, no re-galvanising, none of the upkeep timber and steel demand. A pad that has taken a hard hit or shows a crack through more than a third of its thickness should be pulled from service rather than risked under a rated lift; the cost of a replacement pad is trivial next to the cost of a leg settling mid-pick.

Working near overhead and buried services

Crane outrigger pads sit at the point where the machine meets the ground, often close to buried cable runs or under overhead lines, so the fact that HDPE does not conduct electricity is not just a durability feature — it is a safety one. Unlike steel plate, a polymer pad will not become a live path back through the outrigger float if insulation elsewhere on site fails, and unlike timber it does not become conductive once soaked by rain. That is one more reason plastic crane pads have largely replaced aluminium and timber packing on sites with live services nearby.