This is planning guidance, not engineering. Whether a specific slab can take a specific machine is a call for the structure’s engineer of record. CLE supplies the machine data that review needs on every indoor rental.
KEY TAKEAWAYSA crane loads a floor two different ways. Traveling on tracks is gentle, the weight spreads over the whole track footprint. Lifting on outriggers is not, one pad can briefly carry most of the machine plus the load.
Slab-on-grade handles most mini crane picks. Elevated decks, mezzanines, and anything with occupied space below always get checked by the structure’s engineer first.
Outrigger mats and cribbing are cheap insurance: doubling the mat dimension cuts the pressure under it to a quarter.
While a mini crane tracks across a floor, its weight is spread across the full contact area of both rubber tracks. Ground pressure in travel is low, for most of the fleet it is in the same range as a person walking, which is why these machines can cross finished lobbies and warehouse slabs without drama.
The picture changes the moment the outriggers go down and the boom picks up a load. Now the machine’s weight plus the load is carried on four small pads, and as the boom swings, the share on each pad shifts. At the worst boom position a single outrigger can briefly carry a large share of everything, a common planning assumption is 65 to 80 percent of machine plus load on one pad.
Worst-case pad load ≈ 0.65–0.80 × (machine + load + rigging)
That single number, checked against what sits under the pad, is the heart of every indoor lift plan.
FLOOR TYPETYPICAL CONCERNWHAT TO DO
Slab-on-gradeRarely governs for mini cranes; watch trenches, pits, and thin toppings.Confirm slab thickness if known, mat the outriggers, keep pads off joints and patches.
Elevated composite deckDesigned for distributed live load (often 100 psf), not point loads.Engineer review required. Set pads near columns and girders, spread with cribbing.
Precast plank / parking deckPoint loads between supports and near edges are the risk.Engineer review required. Locate plank bearing lines before placing pads.
MezzanineOften the lightest structure in the building.Assume it cannot take a lifting crane until the engineer says otherwise.
Historic wood / terrazzoCrushing and cosmetic damage as much as strength.Protection layer plus mats, use the lightest machine that makes the pick.
Machine weight is the starting input for every floor check. CLE’s indoor-capable machines, lightest first:
MACHINEWEIGHTINDOOR NOTE
Maeda MC285C-24,765 lbsLightest in the fleet, first pick for weak or finished floors. Jekko SPX532.26,060 lbsLithium, zero emission, longest reach in the light class. Maeda MC3058,750 lbsBi-energy, runs on electric indoors. Maeda MC40512,440 lbsBi-energy, heavier class, grade slabs and verified decks. Jekko SPX65013,007 lbsLithium, zero emission, big capacity where the floor allows. Jekko SPX128015,653 lbsFleet flagship, floor check is mandatory planning. Weights are base machine values from the technical data on each machine page. Add the load, rigging, and any counterweight options in your check.
Pressure is load divided by area, so the mat under the outrigger does most of the work. A worked example with the SPX527 picking 4,000 lbs:
STEP 1Worst pad load ≈ 0.75 × (7,937 + 4,000) ≈ 9,000 lbs
STEP 2On a 2′ × 2′ mat (4 sq ft): 9,000 ÷ 4 = 2,250 psf
STEP 3On 4′ × 4′ cribbing (16 sq ft): 9,000 ÷ 16 = ≈ 560 psf
For scale, a typical office floor is designed around a 100 psf distributed live load. That is why grade slabs shrug these numbers off, why elevated decks need the engineer to check real capacity at the real pad locations, and why bigger mats are the easiest win on any marginal floor.
Call for a review, and budget lead time for it, whenever any of these is true:
The lift happens on any elevated slab, mezzanine, or deck, or there is occupied or excavated space below the floor.
Slab thickness or reinforcement is unknown, or the building is old enough that drawings do not exist.
Outrigger pads land near slab edges, trench lines, pits, vaults, or fresh patches.
The machine parks or works in one spot for days, sustained loading is its own check.
Every indoor rental ships with the numbers the engineer asks for: machine weight and center of gravity, track contact area and travel ground pressure, worst-case outrigger reactions, and footprint drawings. We will also recommend down-class, the lightest machine that makes the pick, and quote electric or bi-energy models so exhaust never becomes the second problem. If the floor genuinely cannot take an outrigger load, the answer is sometimes a carry deck working from outside or a different pick position, and we will tell you that up front.
How much does a mini crane weigh?CLE’s mini cranes run from 4,765 lbs (Maeda MC285C-2) to 15,653 lbs (Jekko SPX1280). Most indoor picks use machines in the 4,700 to 8,000 lb range.
Can a mini crane work on an elevated slab or mezzanine?Often yes, but only after the building’s structural engineer verifies the slab against the machine’s outrigger reactions. Outrigger mats or cribbing spread the point loads.
What is the worst-case outrigger load?During a lift a single outrigger can briefly carry most of the machine plus load weight, plan on 65 to 80 percent. CLE provides per-model outrigger reaction data for lift plans and engineering review.
Does CLE provide floor loading data?Yes. Every rental includes machine weight, track ground pressure, outrigger reactions, and footprint drawings your engineer can check against the slab.
Planning an indoor pick?Send us the load, the floor, and the access route. We’ll match the lightest machine that makes the lift and supply the data your engineer needs.
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