Wide-flange steel beams are commonly stocked in imperial lengths such as 20 ft (about 6.1 m) and 40 ft (about 12.2 m), with some suppliers also carrying 50 ft and 60 ft, and mills rolling longer lengths to order. Most projects don't use full stock lengths. Beams are cut to the length on the drawings, and the practical limit on how long a single piece can be is often delivery and site access, not the steel itself. Here's how beam lengths work and what to check before you order.
Stock lengths vs cut lengths
There are three different "lengths" in a beam order:
- Mill length. Steel mills roll beams in long lengths. Very long lengths are possible for some sections, but they're ordered on the mill's rolling schedule, not off a rack.
- Stock length. Service centres buy from mills and hold inventory in standard lengths. For W-shapes in North America, 20 ft and 40 ft are the most common, and many suppliers also stock 50 ft and 60 ft lengths. Stock lengths are imperial even in Canada, because the North American mill and distribution system runs in feet.
- Cut length. The length your drawings call for. A fabricator or service centre cuts the beam from a stock length to that dimension.
| Stock length | Metric equivalent |
|---|---|
| 20 ft | about 6.1 m |
| 40 ft | about 12.2 m |
| 50 ft | about 15.2 m |
| 60 ft | about 18.3 m |
What's in stock depends on the supplier, the section and the time. Common sizes in light and medium W-shapes are easy to find; very light, very heavy or deep sections may need longer to source, as explained in our Canadian steel beam sizes chart. Always ask before a design depends on an unusual length.
Why cut length affects price
You pay for the steel you use, plus some share of the leftover. A 6.4 m beam cut from a 40 ft (12.2 m) length leaves a 5.8 m drop that may or may not be usable on another job. A 6.0 m beam from a 20 ft length leaves almost nothing.
That doesn't mean you should change a design to fit stock. But where there's a choice, such as several beams of the same size, it helps to know the stock lengths. Two 6.0 m beams can come out of one 40 ft length with little waste. Our post on steel beam cost by length looks at how length feeds into the price.
Remember that the ordered length is not the clear span. A beam needs bearing at each end. The 2024 Ontario Building Code requires beams in Part 9 houses to have at least 89 mm of bearing at end supports (Article 9.23.8.1), and engineered beams may specify more. Steel lintels supporting masonry need at least 150 mm (Sentence 9.20.5.2.(3.1)). Order the length shown on the drawing or the length measured on site including bearing, never the opening width.
How heavy is a long beam?
A metric W-shape's name includes its mass per metre, so weight is easy to estimate: length in metres times the second number in the designation.
| Beam | Length | Approximate weight |
|---|---|---|
| W200x27 | 6 m | 162 kg |
| W250x33 | 9 m | 297 kg |
| W310x39 | 12 m | 468 kg |
| W360x57 | 15 m | 855 kg |
Plates and connections add a little. Weight matters for handling: a long beam that is light per metre is still awkward to carry and can bend under its own weight if lifted from one point. Plan the unload and the route in.
Ontario delivery limits for long beams
Most beam deliveries travel on flatbed trucks or tractor-trailers. Ontario sets maximum dimensions for vehicles and loads, and loads beyond them need an oversize permit. According to the Ministry of Transportation's guide to oversize and overweight vehicles and loads, the legal limits include:
- Width, vehicle including load: 2.6 m
- Height, vehicle and load: 4.15 m
- Length, single vehicle including load: 12.5 m
- Length, combination of vehicles and load: 23 m
- Rear overhang: a permit is needed when the load overhangs more than 4.65 m behind the centre of the rearmost axle
The standard semi-trailer length limit is 16.2 m (53 ft). Ontario's Extended Semitrailer Program allows trailers up to 18.44 m (60 ft 6 in) under a special vehicle configuration permit, provided the overall tractor and trailer length stays at 23 m or less.
What that means in practice:
- Short beams for houses, typically well under 12 m, travel easily on a straight truck or with other material.
- Long beams need a trailer of suitable length, and the overhang must stay within the legal limit.
- Very long beams beyond the legal limits travel under an oversize permit, which adds cost and can restrict travel times and routes. Municipal roads can have their own permit requirements.
The carrier is responsible for the load being legal. As a buyer, what you control is the beam length, which is why designers sometimes split very long members.
Site access: the limit people forget
The truck can carry a long beam; the question is whether it can get to the final position:
- Residential streets may not allow a long trailer to turn in or park.
- Driveways and laneways limit the truck length that can reach the site.
- Overhead wires and trees limit boom truck unloading.
- Inside the building, basement stairs, windows and door openings limit the length that can be carried in.
Measure the route before the beam is cut. If one piece won't fit, the engineer can design a splice so the beam comes in sections and is bolted or welded together in place. A splice isn't something to improvise on site, because its location and connection are part of the structural design. The trade-offs are covered in bolted vs welded beam connections and splices.
Several beams on one job
On a renovation or small building with several beams, a little planning with the length list helps:
- Group by size. Beams of the same section can often be cut from shared stock lengths with less leftover.
- Check the longest piece first. It sets the truck, the unloading method and the access route for the whole delivery.
- Order the posts with the beams. Posts and beams made from the same drawings arrive with matching holes and plates.
- Mark every piece. Each beam should be marked to match the drawing so it goes to the right place on site.
- Phase if needed. If the site can't take everything at once, ask for deliveries timed to the work.
What to tell your supplier
When you order, include:
- Beam size, grade and cut length (or field-measured length with bearing)
- Quantity, and whether several beams of the same size could share stock lengths
- The site address and the longest straight run the delivery truck can reach
- How the beam gets from the truck to its position, with photos if possible
- Whether a splice has been designed, if access is tight
Our guide on where to buy steel beams in Ontario covers the rest of the ordering process.
Beams cut to length and delivered
We supply wide-flange beams cut to length or fully fabricated with plates, holes and connections, and we deliver across the GTA and Ontario, with phased deliveries available to match your schedule. Ask us about lengths and delivery for your site when you request a quote. Send your drawings or beam list, or see our steel products.
Frequently asked questions
What lengths do steel I-beams come in?
Service centres commonly stock wide-flange beams in imperial lengths such as 20 ft and 40 ft, and some carry 50 ft and 60 ft. Mills can roll longer lengths to order. Stock varies by supplier and section, so ask what's on hand.
Can I buy a steel beam cut to any length?
Yes. Fabricators and most service centres cut beams to the length you need. The leftover drop from a stock length is part of the cost, so order lengths that use the stock efficiently where the design allows.
What is the longest steel beam a truck can carry in Ontario?
It depends on the truck and trailer. Ontario's standard limits include 16.2 m for a semi-trailer and 23 m for a combination of vehicles and load, with a rear overhang limit measured from the rearmost axle. Loads beyond the legal limits need an oversize permit.
How do you get a long beam into a house?
Measure the route before ordering. If a one-piece beam won't fit, the engineer can design a splice so it comes in sections and is bolted or welded together in place.
