Steel Erection Lift Planning

Steel erection is not one lifting operation. A single portal frame job might involve two hundred individual picks; a multi-storey frame runs into the thousands. Every one of those is a lifting operation under LOLER 1998 Regulation 8, which means every one must be properly planned by a competent person, appropriately supervised, and carried out safely. The practical job of a steel erection lift plan is to do that across a whole package without producing a document nobody on site will ever read.

The other thing that makes steel different from most lifting work is that the structure being built is not stable until it is finished. A column standing on four holding-down bolts is not a structure — it is a cantilever waiting for a reason to fall over. So the lift plan and the erection sequence are the same conversation. You cannot plan the picks without knowing the order, and the order is driven by when the frame becomes self-supporting.

Fabrication drawing review

Planning starts with the fabrication drawings and the steel schedule. We work through them to establish the weight of every piece, where its centre of gravity sits, and whether it has usable lifting points or needs a purpose-made arrangement. Long slender members — rafters, trusses, plate girders — often need a spreader beam or a two-point pick simply to stop them bending under their own weight while suspended.

This stage catches problems that are cheap to solve on paper and expensive to solve on site. Missing or absent lifting lugs, pieces whose weight puts them outside the intended crane's chart at the radius they have to be placed at, and members that cannot be rotated from the delivery position into the erected position without fouling something are all routinely found here. Confirmed fabricator weights are always preferable to calculated ones, but we can derive them from the drawings where the schedule is incomplete.

Erection sequence and temporary stability

The erection sequence determines the order in which the frame goes up, when temporary bracing goes in, and when it can safely come out. Temporary stability is a design responsibility — it belongs to the temporary works designer and is signed off by the temporary works coordinator appointed under BS 5975, not by the Appointed Person. But the two have to agree. The sequence we plan the lifting around must be the sequence the stability design assumes, and where they conflict, the stability design governs and the lifting gets replanned around it.

In practice the sequence also has to survive contact with the real programme. Steel rarely arrives in the order the drawings imply, deliveries get split, and other trades want the same ground the crane is standing on. A sequence that only works if everything goes to plan is not a sequence, and we build in the flexibility to reorder where the stability design allows it — and flag clearly where it does not.

Crane selection and siting

Crane selection follows from the heaviest pick at the greatest radius, not from the heaviest piece. A five-tonne member placed at 30 metres is a much bigger crane than a twelve-tonne member placed at eight. We work the load chart deductions properly — hook block, slings, spreader beams, lifting accessories — and plan to the net capacity rather than the headline figure. Our mobile crane lift plans cover the same ground for standalone crane work.

Siting is where most steel jobs actually get decided. Outrigger loads from a large mobile crane are concentrated and high, and the ground has to be verified as capable of taking them — made ground, backfilled service trenches, basement slabs and buried drainage are the usual culprits. The plan specifies mat or pad sizes derived from the bearing pressure, not from what happens to be on the wagon. Where access is genuinely tight, a tower crane may be the answer instead, and our comparison of mobile crane versus tower crane sets out how that decision usually falls on steelwork.

Tandem and multi-crane lifts

Tandem lifts come up on steel more than on almost any other type of work — long trusses, pre-assembled frames, and pieces that have to be turned from horizontal to vertical mid-lift. A tandem lift is a complex lift under BS 7121 by definition. Both cranes are derated to allow for load sharing and out-of-plumb effects, one person holds overall control of the operation, and the communication arrangement has to be established and briefed before anything leaves the ground.

The planning detail that gets missed most often is what happens if the lift has to stop part-way. A tandem lift that is halted with the load part-rotated is a materially different loading case from either the start or the end position, and the plan needs to say what the crews do in that situation rather than leaving them to improvise.

What you actually receive

For a typical steel package that means a set of lift plans covering each crane position and load envelope, an erection method statement setting out the sequence and the controls, the supporting risk assessment, crane position and radius drawings marked up on the site layout, exclusion zone arrangements, and the lifting accessory schedule. Everything is signed off by a CPCS A61 Appointed Person and written to the standard Tier 1 principal contractors expect, because they are the people who review it.

Plans should be with the principal contractor seven to ten working days before steel starts arriving. That is not a formality — it is the window in which review comments get resolved, clashes with other trades get spotted, and the erection team gets briefed properly. Packages that arrive the day before the first delivery are the ones that end up being replanned on the hard shoulder of the programme. If a reviewer does come back with comments on our documents, dealing with them is part of the fee, not an extra.