The Steel Erection Process and Sequence

The steel erection process runs in a set order: plan the work and check the foundations, set the columns on their anchor rods, connect beams and bracing to make a stable first bay, extend the frame from there, then plumb it, complete the bolting and field welding, and finish with deck, grout and touch-up. The detailed sequence for any job is set by the erector's erection plan and the erection drawings, and the whole point of the sequence is to keep the frame stable at every stage.

This guide walks through each stage the way it happens on a typical Ontario commercial or industrial frame, then shows how the same steps scale down to a beam and posts in a house. For who does the work and how the contracts split, see steel fabrication vs erection.

Before the steel arrives: planning and the method statement

Erection starts on paper. Before the first truck rolls, the erector puts together an erection plan, often called a method statement or erection procedure. A useful one covers:

• Scope and drawings. Which erection drawings, revisions and pieces are included, and what is excluded (deck, grout, touch-up, miscellaneous steel).
• Sequence. The order the bays, floors or areas go up, starting from the bay that will be braced first.
• Cranes and lifts. Crane type and location, the heaviest and farthest pick, rigging, and a lift plan for anything unusual.
• Stability. Temporary bracing, guy cables and the point at which the permanent bracing or deck takes over.
• Connections. Which bolts are snug-tight and which are pretensioned, the tightening method, and the field welds.
• Safety. Fall protection, access to connection points, overhead protection and exclusion zones under the lift.
• Inspection and records. Bolt and weld inspection, survey checks and who signs off.

In Ontario the safety side of that plan has to meet the construction regulation under the Occupational Health and Safety Act, O. Reg. 213/91. Our post on steel erection safety in Ontario covers those rules in detail.

Checking the foundations

The most common cause of erection delays is the concrete, not the steel. Before steel arrives, the general contractor or erector should:

1. Survey the anchor rods for location, projection above concrete and elevation, against the anchor rod plan.
2. Check bearing elevations on walls, piers and pilasters where beams sit on concrete or masonry.
3. Confirm the concrete has reached the strength the engineer requires before it takes load.
4. Set elevation control with levelling nuts, shim packs or levelling plates, depending on the base detail.

Anchor rods that are out of position can sometimes be dealt with by slotting or redrilling a base plate, but any fix to a structural connection needs the engineer's approval. Finding the problem a week early is far cheaper than finding it with a column in the air.

Delivery, shake-out and staging

Steel should arrive in erection sequence, with the first pieces to be set on top of the load. Phased deliveries keep the laydown area workable and stop pieces sitting for weeks.

On arrival the crew "shakes out" the steel: unloads it, checks piece marks against the shipping list, looks for damage, and lays it out near where it will be lifted, on dunnage and off the ground. Every piece carries a mark that matches the erection drawings, so the crew knows exactly where it goes. Bolts, nuts and washers are kept dry and sorted by type and length, since mixing up bolt grades or lengths is an easy mistake to make on a busy deck.

Setting columns

Columns usually go first in each area. A typical column erection goes like this:

1. Rig and lift. The column is lifted, usually from a lifting lug or a hole near the top, with tag lines to control it.
2. Land on the anchor rods. The base plate is lowered over the rods onto levelling nuts, shims or a pre-set levelling plate.
3. Nut up before releasing. Nuts go on the anchor rods before the crane takes the load off, so the column is held at the base.
4. Stabilize. The column is guyed or braced until beams tie it into the frame.

CSA S16 includes a requirement, aimed at erection safety, that columns have at least four anchor rods arranged so they give the column a lever arm against overturning in more than one direction; CISC has published guidance on it for the 2014 edition. Where four rods aren't feasible, such as some small posts, special precautions are needed and the engineer and erector agree on them.

Connecting beams and making the first bay stable

With two or more columns standing, the beams go in. Ironworkers called connectors receive each beam, line up the holes with drift pins and put in enough bolts to hold it before the crane unhooks. Those first bolts are temporary in the sense that the connection is not finished, but they have to be enough to carry the piece safely.

Ontario's construction regulation has a specific rule for one common situation: where two beams or columns connect to a common member, the connection must be a clipped double connection, or the first member must be held in a seated connection. The idea is that the first beam is never left hanging on bolts that will be pulled out to install the second.

The first goal is a stable, braced bay: columns, beams and the permanent bracing (or temporary bracing) in one bay, so it can stand on its own. The rest of the frame is then built out from that bay. A frame that goes up as a row of unbraced columns and beams relies entirely on temporary guying, which is slower and riskier.

Erection with a crane

Most building frames go up with a mobile crane, and larger projects may use a tower crane. Crane choice depends on the heaviest piece at the longest reach, site access and ground conditions. On houses and tight sites where a crane can't reach, beams are often moved in by hand with rollers, lifts and jacks instead.

Plumbing, aligning and final bolting

Once an area is erected with temporary bolting, the crew plumbs and aligns it:

• Columns are checked for plumb with a level, a plumb line or survey instrument.
• The frame is pulled into line with cables and turnbuckles, or adjusted at the bases.
• Beam elevations and spacing are checked against the drawings.

The erection tolerances come from CSA S16 and the project specification. Only after a section is plumb are the connections completed, because final bolting or welding locks in whatever position the frame is in.

Final bolting then fills every hole and brings the bolts to the condition the drawings specify. Most simple shear connections are snug-tight. Connections the engineer designates as pretensioned or slip-critical are tightened by a recognized method such as turn-of-nut and inspected. The bolting requirements live in CSA S16 and the project specification, so check the drawings rather than assuming.

Field welding follows the same logic: welds shown on the erection drawings, such as some moment connections, column splices and bracing connections, are made after alignment. Companies welding structural steel designed to CSA S16 need CWB certification, and that applies to field welds as much as shop welds. See why hire a CWB certified fabricator for what that covers.

Floors, deck and moving up

In a multi-storey building the frame goes up in tiers. The regulation requires temporary or permanent flooring to be installed progressively as the building goes up, and limits how far above that flooring work can be carried out unless workers are protected by a scaffold, safety net or fall arrest system. That ties the steel sequence to the deck sequence: steel deck or temporary planking follows the frame up rather than waiting until the end.

Steel deck, once fastened, also acts as a diaphragm that stiffens the frame, which is one reason temporary bracing can often come out only after the deck is down. Removing temporary bracing is the engineer's or erector's call, never a site improvisation.

Close-out: grout, touch-up and inspection

The last stage turns a standing frame into a finished one:

• Grouting base plates. Once the columns are plumb and loaded enough, non-shrink grout is packed under the base plates. Our guide to grouting base plates covers the materials and method.
• Touch-up. Primer or paint is touched up at field welds, bolted connections and damaged areas where the contract includes it.
• Inspection. Bolting, welding and alignment are checked by the inspector or engineer as the specification requires.
• Punch list. Missing bolts, loose connections and small fit-up items are cleared before the next trades take over.

The same sequence on a house

A basement beam and posts follows the same logic on a small scale. The opening is shored first, footings for the posts are checked, the beam is brought in and set on its bearings, posts are set under it on their footings, and the beam is fastened, levelled and tied to the floor framing. Only then is the temporary shoring removed. The work needs a design from a qualified designer or engineer and usually a building permit. Our guide to installing a steel beam in a basement explains what to expect on a residential job.

Supply and installation from one shop

We prepare shop drawings in-house, fabricate and mark every piece to match them, deliver across the GTA and Ontario with phased deliveries to suit your schedule, and install structural steel from basement beams and posts to larger commercial and high-rise frames. Work continues year-round. If you are planning erection, ask us how we'd sequence deliveries for your site.

Send your drawings for a quote, or see our fabrication and installation services.