What steel erection actually involves, stage by stage
Erection is the visible part of a longer sequence. Knowing the stages makes it much easier to see where a programme is going to slip.
Steel arriving on site and going up looks like a single operation. It is the end of a sequence, and most delays are caused several stages earlier.
1. Design and connection detailing
The frame is designed, then every connection is detailed: plates, bolts, welds, stiffeners. This is where most of the drawing work lives, and where a late change is most expensive, because it ripples through fabrication.
2. Shop drawings and approval
Fabrication drawings are produced and issued for approval. Nothing is cut until they come back. Approval turnaround is a common and underestimated programme item.
3. Fabrication
Members are cut, drilled, welded and assembled, then surface-prepared and coated. Each piece gets a mark that matches the erection drawings — that mark is how the right member ends up in the right place on site.
4. Site preparation
Running in parallel: foundations cast, holding-down bolts set, levels surveyed and confirmed. Access and crane standing positions prepared. Steel that arrives before this is finished sits in a lay-down area costing money.
5. Delivery and lay-down
Members are delivered in erection sequence where the site allows it. Where it does not, they are laid down so the right piece can be reached without moving three others first.
6. Erection
Columns first, then primary beams, then bracing, then secondary steelwork. Members are placed, bolted loosely, plumbed and aligned, then finally bolted or welded. The frame is not stable until the bracing is in, which is why temporary stability is designed rather than improvised.
7. Inspection and handover
Bolt tightness, weld condition, alignment and levels checked and recorded. Coating damage made good. Then the frame is released to the trades that follow.
Where the programme usually goes
Approval turnaround, holding-down bolt accuracy, and crane access. Those three account for most of the lost time on a steel package, and all three are settled before erection begins.