Steel fabrication happens in the shop and erection happens on site. The fabricator cuts, drills, fits, welds, paints and marks every piece to the shop drawings; the erector unloads those pieces, lifts them into place, plumbs the frame and makes the field bolts and welds. One company can do both, or they can be separate contracts. Either way, most problems on a steel job come from the handful of items that sit between the two scopes, so this guide spends as much time on those as on the definitions.
What the fabricator does
Fabrication turns mill material into finished, numbered pieces. A typical structural fabrication scope includes:
- Shop drawings. Erection drawings that show where every piece goes, and piece drawings the shop builds from. The engineer of record reviews them before fabrication.
- Material. Buying beams, columns, HSS, plate and angle in the grades specified.
- Cutting and holes. Sawing members to length, coping beam ends, drilling or punching bolt holes.
- Fitting and shop welding. Attaching base plates, cap plates, shear tabs, end plates, stiffeners and bracing gussets, then welding them to CSA W59.
- Specialty work. Cambering beams, for example, so they finish level under load.
- Finish. Cleaning and priming or painting where specified.
- Marking, bundling and shipping. Each piece is marked to match the erection drawings and loaded in the order the erector needs it.
Good fabrication is mostly invisible on site. Holes line up, pieces arrive in sequence, and the erector never has to cut or modify anything to make it fit.
What the erector does
Erection turns those pieces into a standing structure:
- Receiving and unloading deliveries, and checking pieces against the shipping list.
- Hoisting with a crane or other equipment, according to a lift plan.
- Setting columns on their base plates and anchor rods, and connecting beams to them.
- Plumbing, levelling and aligning the frame to the erection tolerances in CSA S16 and the project specification.
- Temporary bracing to keep the frame stable until the permanent bracing, deck or floors are in.
- Final bolting, including any pretensioned bolts the drawings require.
- Field welding shown on the drawings.
- Touch-up of primer at field connections and damaged areas, where it is in the contract.
Erection is governed by workplace safety law as well as building standards. In Ontario, construction projects fall under the Occupational Health and Safety Act and its construction regulation (O. Reg. 213/91), which covers fall protection and other hazards that are part of every erection job. Our guide to steel erection safety in Ontario goes into that side.
Do steel erectors weld?
Yes. Most welding is done in the shop, where conditions are controlled and the work can be positioned for easy access. But some welds can only be made after the steel is standing: certain moment connections, column splices, welding of steel deck, and connections the designer chose to weld for geometry or tolerance reasons. Those are made by the erector's welders.
Field welds are held to the same standard as shop welds. The Ontario Building Code points to Clause 24.3 of CSA S16 for the qualification of fabricators and erectors of welded construction, and that clause is the basis for the requirement that companies welding structural steel are certified by the Canadian Welding Bureau. So when you hire an erector who will weld, confirm their CWB certification just as you would the fabricator's. Our post on why to hire a CWB certified fabricator explains what that certification covers, and structural welding services compares shop and field welding in more detail.
Steel erector vs ironworker
The two terms get used interchangeably, but they mean different things:
- Ironworker is the trade. Ironworkers raise and connect structural steel, bolt and weld it, and also install rebar (reinforcing ironworkers) and miscellaneous and ornamental metal. It is an apprenticeable trade in Ontario; Skilled Trades Ontario has the current trade details.
- Steel erector is the contractor: the company that signs the erection contract, supplies the crews, crane and equipment, plans the lifts and is responsible for safety and quality on its scope.
So the erector employs ironworkers. A fabricator with its own field crews is also, in effect, an erector.
How fabrication and erection get contracted
There are three common arrangements:
| Arrangement | How it works | Watch for |
|---|---|---|
| Fabricate only (supply) | The fabricator delivers to site; the owner or general contractor hires an erector separately | Who pays when a piece doesn't fit, and who owns delays between the two |
| Fabricate and erect, one contract | The fabricator erects with its own crews or a subcontractor it manages | Clear inclusions and exclusions; it simplifies responsibility |
| Furnish, fabricate and erect on a larger package | Steel is one trade package within a general contract | Interface with concrete, deck and other trades |
A single contract for fabrication and erection has one obvious advantage: when a hole doesn't line up, there's no argument about whether the shop or the field caused it. On smaller jobs, such as a residential beam and posts, one supplier who fabricates and installs is usually the simplest path. The cost side of a combined scope is covered in installed structural steel cost.
The gaps between the two scopes
These are the items that cause disputes because each party assumes the other has them. Settle them in writing before you sign, whatever the arrangement:
- Anchor rods. Who supplies them, who sets them in the concrete, and who surveys their location before steel arrives. Rods in the wrong place stop erection cold.
- Grout under base plates. Often by others; confirm.
- Levelling plates or shims under columns.
- Crane and hoisting. Who supplies and pays for it, and for how long.
- Site access and laydown. Ground that can take a crane and trucks, and space to shake out steel.
- Survey and layout. Gridlines and elevations the erector works from.
- Temporary bracing design and when it can come out.
- Field touch-up painting and final painting.
- Field fixes. How mis-fits are reported, who corrects them and how back-charges are agreed.
- Miscellaneous steel. Lintels, stairs, railings and loose angles are sometimes in the steel package and sometimes not.
- Inspection and testing. Who pays for the inspection firm, and who provides access.
The Canadian Institute of Steel Construction publishes a Code of Standard Practice for structural steel that many contracts reference for default answers to these questions. Even so, writing the answers into the quote and contract is the reliable way to avoid surprises.
How the two work together on site
The handoff runs both ways. The erector should see the shop drawings before they are finalized, because connection details and piece lengths affect how the steel is lifted and connected. The fabricator needs the erection sequence, because it decides the shipping sequence. Pieces that arrive in the order they will be lifted save crane time; pieces that arrive in the wrong order sit on the ground and get handled twice.
When something doesn't fit, report it with the piece mark and a photo before anyone cuts or welds. A shop that can see the problem can often explain it in minutes, and modifying steel in the field without the engineer knowing can create a bigger problem than the original mis-fit. If you are choosing an erector, our guide to hiring steel erectors in Ontario covers what to ask.
Fabrication and installation from one shop
We fabricate structural steel to shop drawings we prepare in-house, with CWB certified welding, and we supply and install structural steel and rebar, from basement beams and posts on residential builds to larger commercial projects. Delivery is available across the GTA and Ontario, with phased deliveries to match your schedule. Send us your drawings for a free take-off and quote, and tell us whether you need supply only or supply and install. See our services for the full scope.
Frequently asked questions
What is the difference between steel fabrication and erection?
Fabrication is shop work: cutting, drilling, fitting, welding, painting and marking each piece to the shop drawings. Erection is site work: unloading, lifting the pieces into place, plumbing, bolting and field welding them into a finished frame.
Do steel erectors weld?
Yes. Erectors make the field welds shown on the drawings, such as some moment connections, column splices and deck welding. For structures designed to CSA S16, the companies doing that welding have to meet the same CWB certification requirement as fabricators.
Is a steel erector the same as an ironworker?
Not quite. Ironworker is the trade, the skilled worker who raises, connects and welds steel or places rebar. A steel erector is the company that contracts to erect the steel and employs the ironworkers, crane crews and supervisors.
Can one company fabricate and erect?
Yes. Some fabricators have their own erection crews, others subcontract erection, and some owners hire the fabricator and erector separately. A single contract for both puts fit-up and field problems in one set of hands.
