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I-Joists vs Floor Trusses vs Sawn Joists in an Ontario House (2026): Spans, Ducts and Drains, Stiffness, Hole Rules and What a Floor Costs
Framing & Building Systems
Sawn Joists, I-Joists or Floor Trusses: Pick the Floor That Has Room for the Ductwork
All three hold up a floor. The differences are how far they reach without a beam, how stiff they feel underfoot, how much they shrink, and where the furnace guy and the plumber get to run their pipes. This page compares the three, shows the only per-foot price we could find, works out a real floor, and says what goes over an ICF basement.
The numbers
$4 to $9I-joist per lineal foot, by depth and series (Level 1, thin)
$3,472 to $7,812I-joists for a 28 x 40 ft floor, our estimate
quoted per jobopen-web floor truss package
$40 a sq ftwhole-house framing, labour and materials, our planning number (Level 2)
| Floor item | Level | Range | Note |
|---|---|---|---|
| I-joists, per lineal foot | Level 1, material | $4 to $9 | a Canadian calculator site, no named data |
| Sawn lumber joists (2×10, 2×12) | Level 1, material | ask your yard | commodity prices move month to month |
| Open-web floor truss package | Level 1, material | quoted per job | no published price found |
| Whole-house engineered floor package | Level 1, material | quoted per job | no published price found |
| Subfloor replaced in a renovation | installed renovation line | adds $2 to $5 a sq ft | a GTA contractor |
| House framing, labour and materials | Level 2, framed structure | $30 to $60 a sq ft | a Canadian finance guide; $40 our planning number |
October 2026, before HST. Example: a floor 40 ft long and 28 ft wide (1,120 sq ft) with joists at 16 inches on centre is 40 x 12 / 16 = 30 spaces, so 31 joists. At 28 ft of joist per line, over a centre beam, that is 31 x 28 = 868 lineal feet: 868 x $4 = $3,472 to 868 x $9 = $7,812, about $3.10 to $6.98 a sq ft of floor. That is the joists only. Rim board, hangers, blocking, the beam, the subfloor, delivery and the framer are all extra.
Why Ontario prices are all over the map: the price guides and contractors we checked for this page did not agree on what framing costs, and almost none would price a floor on its own. For labour and materials, a Canadian proptech blog said $11 a sq ft and a Canadian finance guide said $30 to $60. For the floor itself we found one calculator site at $4 to $9 a lineal foot of I-joist and nothing else. The gap is level of completion, floor area vs footprint, and whether the beam, subfloor and labour are in. Budget $40 a sq ft for the whole frame and get two or three quotes on the same written scope.
Three Ways to Hold Up a Floor
Sawn joists. Plain 2x10s or 2x12s, the way houses were framed for a century. Any framer can cut them on site, and the Part 9 span tables say how far each size and grade can go. The catch is that sawn lumber arrives with water in it and shrinks across its depth as it dries, like bacon after you fry it. A 2×12 floor loses a little height in the first heating season, and that shows up as nail pops and drywall cracks. The lumber shrinkage page explains it.
I-joists. A top and bottom flange of solid or engineered wood with a thin OSB web between them, shaped like a steel I-beam. They are made dry and straight, they come in long lengths, and they span further than a sawn joist of the same depth. They do not forgive a saw. The web can only be cut where the maker says, and the flanges never.
Open-web floor trusses. Built in a truss plant from 2x4s laid flat and joined with steel plates, with open triangles through the middle. They reach further again, and a duct or a drain passes straight through the webs. The trade-off is that every truss is designed for one place in one house. Change the stairs after they are ordered and you are waiting for the plant.
Deck joists are a different animal: pressure-treated, outdoors and wet. Those have their own page on deck framing, joists and beams.
Ducts, Drains and the Hole Chart
This is where floors go wrong. A trunk duct is a big rectangle, a toilet drain needs slope, and both want to cross the joists at right angles. With sawn joists, Part 9 limits how big a notch or hole can be and where it goes. With I-joists the rule is the maker’s hole chart: a list of how big a hole can be at each distance from the bearing. The Code accepts I-joists when they are installed to their CCMC evaluation and the maker’s instructions, and the hole chart is part of those instructions.
- Never cut, notch or drill an I-joist flange. Not a little bit, not for a drain. The flange is the part doing the work.
- Holes in the web go where the chart allows, usually toward the middle of the span and away from the ends, and many I-joists have knockouts for wiring.
- Plan the trunk duct before the floor is ordered. With I-joists it usually runs under the joists in a bulkhead or in a dropped ceiling chase. With floor trusses the plant can leave a clear chase for it.
- A cut truss or joist is not fixed with a sister board and good intentions. It is fixed with a repair detail from the maker or an engineer, in writing, and the inspector will want to see it.
Span Is Not the Same as Stiffness
A floor can be strong enough and still feel like a trampoline. Span tables and maker’s software give you a floor the Code will accept. Whether it feels solid when someone walks past the china cabinet is a separate question, and the answer is depth, spacing and a glued and screwed subfloor. That is the whole subject of the bouncy and squeaky floors page.
The 2024 Code adds another reason to plan the floor with the walls. Under the new bracing rules in Subsection 9.23.13, walls with required braced wall panels must be continuously supported by floor joists, blocking or rim joists. A braced panel sitting over a gap in the floor framing is a detail the plans examiner will catch, and the wall bracing page explains what that means for open plans and walkouts.
Sawn joist spans come from the tables at the end of Part 9. Engineered joists and floor trusses are sized by the maker, and an LVL beam needs engineered sizing software output or an engineer’s stamped report. Anything with heavy point loads or unusual spans goes to an engineer.
What Goes Over an ICF Basement and Under a Radiant Floor
I build ICF houses with hydronic radiant floors. On those houses the basement and exterior walls are ICF, and the floors are engineered I-joists bearing on the ICF walls. So I work with engineered floors on every house, and the questions below are the ones to settle on any ICF house. The wall side of it is on ICFPro.ca.
- Decide how the floor meets the concrete before the wall is poured. The floor either sits on top of the wall or hangs off a ledger anchored into it. Anchors and pockets go in with the concrete, and the connection detail comes from the ICF system’s instructions or the designer.
- Tell the floor designer about the radiant floor. Tubing set in a poured topping adds a lot of weight to a wood floor. Tubing in plates under the subfloor adds very little. The floor has to be sized for whichever one you are getting.
- Keep the joist bays clear for the heating side. Radiant tubing, manifolds and supply lines run through the floor framing too. With I-joists that means holes planned on the chart, not drilled on the day.
- Engineered floors suit a radiant house. A floor that does not shrink keeps the finish floor and the tile where they were put, which matters when the floor is also the heater.
For what the whole frame costs on top of the floor, see the house framing cost page, and the rest of the floor and roof subjects are on the floors and roof framing hub.
Questions people ask
Are I-joists better than 2x10s?
For most new houses, yes: they are straighter, they shrink far less, and they span further at the same depth. Sawn joists are easier to cut and repair on site. Neither is better if it is drilled where it should not be.
How much do I-joists cost per foot in Canada?
One Canadian calculator site gives $4 to $9 a lineal foot by depth and series, with no named data behind it. Ask your yard or truss plant for a floor package quote on your drawings, which is the only number that counts.
Can I drill a hole in an I-joist?
Only in the web, only where the maker’s hole chart allows, and never in the flange. If a hole is already in the wrong place, the fix is a written repair detail from the maker or an engineer.
Why would I choose open-web floor trusses?
Long clear spans and easy ductwork. The ducts, drains and wiring pass through the open webs. The trade-off is that each truss is made for one spot and cannot be cut down on site.
Do engineered floors need an engineer?
The maker sizes them with its own software and installation guide, and the Code accepts them when installed that way. Heavy point loads, odd spans and beams outside Part 9 still go to an engineer.
Price the frame, floors included
The house framing cost calculator works out labour only or labour and materials by floor area and shape, with the truss package and the crane. If you already have framing or floor package quotes, the $99 review reads up to three of them and tells you what each one left out.
Sources and further reading
- Trusses and engineered wood products declaration (Arran-Elderslie): how a municipality accepts trusses and engineered floor joists, and who is responsible for bracing and anchorage.
- Canadian Construction Materials Centre evaluations: what a CCMC evaluation is, and why no building department is bound to accept one.
- The 2024 Ontario Building Code: Ontario on the 2024 Code: in force January 1, 2025, and harmonized with the national codes.
