Steel fabrication cost per tonne in Ontario is worked out from the job, not looked up from a table. Fabricators estimate the shop hours for every piece and connection, add material, finish and drawings, then divide by the weight. A tonne of simple beams and a tonne of plates, posts and braced connections can be very different numbers. This guide walks through how a fabrication estimate is built, what moves it, and how to judge whether quotes are comparable. For a price on your project, send us your drawings.
Fabrication cost vs the full steel price
"Fabrication" gets used loosely. In this post it means the shop work and the costs that travel with it:
- Material: beams, columns, HSS, channels, angles and plate, plus connection material and bolts.
- Shop labour: cutting, drilling or punching, coping, fitting, welding, grinding and cleaning.
- Finish: bare steel, shop primer or a specified coating system.
- Shop drawings: often included in the fabricator's price.
- Handling and loading: marking, bundling, loading and strapping for delivery.
Erection on site is a separate cost, covered in steel erection cost per tonne. If you want the full supplied, fabricated and erected picture, see structural steel price per tonne in Canada.
How a fabrication estimate is built
Most fabricators follow a version of this process when they price structural steel.
1. Take-off
The estimator lists every member from the structural drawings by size and length, then works out its weight using the mass per metre from the steel handbook. Plates, connection material and miscellaneous items are measured where details exist, or carried as an allowance until shop drawings are done.
2. Group by type of work
Columns, beams, bracing, girts and purlins, lintels, posts, plates and miscellaneous metals are grouped separately, because each group takes different shop effort per tonne.
3. Count pieces and connections
This is where the estimate is really made. For each group, the estimator counts pieces, ends, holes, copes, stiffeners and welded attachments. A beam with a bolted shear tab at each end is a few operations. A column with base and cap plates, stiffeners and connection plates on several faces is many.
4. Apply shop hours
Each operation gets an hours allowance based on the shop's equipment and experience: saw cutting, drilling, coping, layout and fitting, welding by weld size and length, grinding and cleaning. Automated drilling and cutting lines reduce hours on repetitive work; hand layout and manual fitting take longer.
5. Price the material
Material is priced from current supplier quotes, with an allowance for drops and offcuts. How well member lengths nest into stock lengths matters here. Awkward lengths that leave long, unusable offcuts add waste.
6. Add finish, consumables and drawings
Primer or paint, welding wire and gas, saw blades and other consumables, and the detailing hours for shop and erection drawings. See steel detailing cost per tonne for what drives that last item.
7. Add handling, overhead and margin
Marking, loading, shop overhead, quality control and the fabricator's margin. Only after all of this does a per-tonne or per-kg figure appear, as total cost divided by weight.
What drives fabrication cost per tonne
Pieces per tonne
The single biggest driver. Light members, short pieces and lots of plates mean more handling and more operations for each tonne. That's why posts, lintels and small plates cost more per tonne than long, heavy beams.
Connection type and complexity
Simple bolted shear connections are the fastest to fabricate. Moment connections, full-penetration welds, skewed or sloped members, and connections that differ from one beam to the next all add hours. Whether the shop or site makes the welds also matters.
Welding
Weld volume, position and inspection requirements drive welding hours. For structural steel designed to CSA S16, which the 2024 Ontario Building Code references, fabricators doing the welding must be certified by the Canadian Welding Bureau to CSA W47.1. Certification is a fixed requirement of doing the work, not an optional extra.
Repetition
Repeated members with the same connections move through the shop quickly. One-off members, each different, slow everything down.
Special operations
Cambering, curved members, built-up sections and architecturally exposed steel with ground welds or tight tolerances all add cost. Heat cambering, for example, is a separate process with its own setup.
Finish
Bare steel for members that will be enclosed is the simplest. Shop primer adds surface preparation and coating time. Specified paint systems and fire-resistive coatings add more, and galvanizing adds a trip to a galvanizing plant.
Material market and origin
Mill prices move, and trade measures have added movement in Canada since 2025. Where the steel comes from now affects what it costs, and fabricators may hold prices for shorter periods or include escalation terms. Our post on steel price increases and tariffs in Canada covers that in more detail. This is also why "fabrication steel price per ton today" has no single answer: the material share moves with the market, while the labour share depends on your drawings.
Drawing quality and changes
Incomplete drawings mean allowances and assumptions in the estimate. Design changes after fabrication starts can mean rework or scrap.
Per tonne, per kg and per ton: reading the units
Fabrication rates are quoted in different units depending on who's talking:
| Unit | Equal to |
|---|---|
| 1 tonne (metric) | 1,000 kg, about 2,204.6 lb |
| 1 kg | about 2.2 lb |
| 1 US short ton | 2,000 lb, about 907 kg |
A rate per tonne divided by 1,000 gives a rate per kg. If a source says "per ton," check whether it means a metric tonne or a US short ton, because the difference is about 10 percent of the weight.
Be careful with rates found online. Many come from other countries, where labour costs, certification rules and material sourcing are different, or from a single project type that may look nothing like yours. A fabrication rate per kg is only meaningful for the job it was calculated on.
How to compare fabrication quotes
Before comparing prices, make sure the quotes cover the same thing:
- Same drawings and revision, and a similar tonnage. Ask each bidder what tonnage they carried.
- Connection material and bolts included, and who designs the connections.
- Shop drawings included, and how many revision cycles.
- Finish stated clearly: bare, primer or a named system.
- Miscellaneous metals in or out. Stairs, rails and lintels are labour-heavy for their weight.
- Delivery included, with phasing if your schedule needs it.
- Certification: is the shop CWB certified to CSA W47.1?
- Validity and escalation: how long the price is held, and how material increases are handled.
For smaller one-off pieces, where hourly shop rates and minimum charges matter more than tonnage, see how much custom steel fabrication costs.
How to keep fabrication cost down
- Issue complete drawings. Sizes, lengths, connection details and finishes all shown.
- Ask your engineer about standard, repeated connections where the design allows it.
- Avoid unnecessary field welding and over-specified finishes on members that will be hidden.
- Freeze the design before shop drawings are approved.
- Bundle the work. Detailing, fabrication and delivery from one shop avoids hand-offs and duplicate checks.
Get a fabrication quote from your drawings
We fit, cut, weld, grind, mark and bundle structural steel to your shop drawings in our CWB-certified shop, with shop drawings produced in-house and engineering services available where a project needs them. Every piece is marked to match the drawings, and we deliver and install across the GTA and Ontario.
Send your structural drawings for a free take-off and quote, or see the structural steel products we supply and fabricate.
Frequently asked questions
How do you estimate structural steel fabrication cost?
Start with a take-off of every member and plate from the drawings, then estimate shop hours for each operation (cutting, drilling, coping, fitting, welding, cleaning and finishing) by piece and connection. Add material with an allowance for cutting waste, consumables, finish, handling and shop drawings.
Is steel fabrication priced per tonne or per kg?
Both are used, and they are the same thing in different units: one tonne is 1,000 kg. Either way, the rate is usually the result of a piece-by-piece estimate divided by weight, so it changes from job to job.
Why do light steel members cost more per tonne to fabricate?
Shop labour follows pieces, cuts, holes and welds, not weight. A tonne of small members, plates and connections needs far more handling and processing than a tonne of large beams with simple end connections.
Can I use a fabrication rate per kg from another country or an online calculator?
Not reliably. Labour rates, certification requirements, material sourcing and trade measures differ by market, and a single rate ignores your job's piece count and connections. A take-off from your drawings is the only accurate basis.
