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Trusses vs Rafters and Cathedral Ceilings in an Ontario House (2026): Scissor Trusses, Structural Ridge Beams, Room-in-Attic Trusses, Insulation, Venting and Cost
Framing & Building Systems
Trusses or Rafters: Decide What You Want Above the Ceiling First
If the ceiling is flat and the attic is just for insulation, trusses win on price and speed nearly every time. If you want a vaulted great room, a loft or real storage in the roof, the choice gets more interesting, and so does the insulation. This page compares trusses with stick-framed rafters, explains scissor trusses, ridge beams and room-in-attic trusses, and covers the part of a cathedral ceiling that goes wrong most often: the venting.
The numbers
| Roof framing item | Level | Range | Note |
|---|---|---|---|
| Common gable trusses, delivered, per foot of span | Level 1, kit | $5.00 to $9.00 | two Canadian calculator sites |
| Hip roof trusses | Level 1, kit | about 15% more than gable | a Canadian calculator site |
| Scissor or room-in-attic trusses | Level 1, kit | quoted per job | no published price found |
| Stick-framed rafter roof or cathedral ceiling | Level 2, installed | quoted per job | no published price found |
| Journeyman framer | Level 2, labour | $50 to $80 an hour | a GTA framing contractor |
| Boom truck and crew, half day | Level 2, setting | $900 to $1,400 | a calculator site |
| Whole roof structure, per house | Level 2, scope not stated | $10,000 to $30,000 | a Canadian finance guide |
October 2026, before HST. A rafter roof is mostly labour: the framer cuts every rafter on site, and the ridge beam and its posts are an engineered item of their own. That is one reason nobody publishes a square-foot price for it. Ask for the roof priced both ways on the same drawings. The truss side is worked out in detail on the roof truss cost page.
Why Ontario prices are all over the map: the price guides and companies we checked could not agree on the roof frame, and none would price a rafter roof at all. One Canadian calculator site said $5.00 to $7.50 a foot of span for trusses, another about $9. A Canadian finance guide said $10,000 to $30,000 for the whole roof structure. Lifting runs $900 to $1,400 for a half-day boom truck, or $700 to $1,500 a day for a crane from a Hamilton company. The gap is trusses alone vs a framed roof, the shape, and the ridge beam. Budget about $7 a foot of span for plain trusses, our estimate, and get two or three quotes on the same written scope.
Trusses: Cheap, Fast and Not Negotiable Later
A truss is a whole roof triangle built in a plant, top chord, bottom chord and webs, designed by software and sealed by a Professional Engineer. It spans from outside wall to outside wall without needing an interior bearing wall, which is why open plans love them. A crew can set and brace a simple house in a day.
The price of that is the attic. It is full of webs, so it is good for insulation and not much else. And a truss is finished when it arrives: nobody cuts, notches or drills a truss except as the truss engineer allows in writing. Changing your mind about an attic room after the trusses are up is a new roof, not a renovation.
Trusses also move. The bottom chord sits in warm, dry insulation and shrinks more than the top chord in the cold, and the middle can lift off an interior wall. That is covered on the truss uplift page.
Rafters: More Labour, More Room, More Engineering
A stick-framed roof is rafters cut on site from the ridge down to the wall plate. Ordinary rafter sizes for ordinary loads come from the span tables at the end of Part 9. What the tables do not do for you is stop the roof pushing the walls out.
Rafters want to spread at the bottom like a stepladder without its brace. There are two ways to stop them. With ceiling joists or ties across the bottom, the roof is a triangle again and the ridge board is just a nailing strip. With a cathedral ceiling there are no ties, so the ridge has to be a structural ridge beam that holds the top of every rafter up. That beam carries a big load, and the posts at each end carry it down to the foundation.
- A structural ridge beam is engineered. An LVL needs engineered sizing software output or an engineer’s stamped report, and steel or big glulam beams and point loads take you outside Part 9 to an engineer.
- The posts have to land on something. A footing, not a subfloor. The inspector follows the load down.
- Connections matter more in the 2024 Code. It added nailing requirements, including rafter-to-joist connections, and increased anchorage.
Where the framing is exposed timber, with big members spaced more than 600 mm apart, that is post and beam work designed by an engineer. The post and beam homes page covers it.
Scissor Trusses and Room-in-Attic Trusses
Scissor trusses give you a vaulted ceiling with trusses. The bottom chords slope up toward the middle, so the ceiling rises at a lower pitch than the roof outside. A 10/12 roof might give you a 5/12 ceiling. You get the cathedral look without a ridge beam, and the plant engineers it like any other truss. The catch is the insulation: at the outside walls the space between ceiling and roof gets thin, so ask for a raised heel.
Room-in-attic trusses, sometimes called attic frame trusses, leave a rectangle open in the middle for a room or real storage, with a floor built into the bottom chord. They are big and heavy, often need a crane, and the floor inside them has to be designed for the load you plan to put on it. Price them per job; we found no published figure.
Either way, decide before the order. Scissor or attic trusses are not something a framer can improvise from common trusses on the day.
Insulating and Venting a Cathedral Ceiling
An attic over a flat ceiling is easy: lots of depth for insulation and lots of air above it. A cathedral ceiling squeezes both into the depth of the rafter or the scissor truss. That is where frost, drips and stained ceilings come from.
- Air seal the ceiling first. Warm, moist house air leaking through pot lights and gaps meets a cold roof deck and turns to frost, then to drips on the first sunny day. A tight ceiling is the main defence. The insulation and air sealing section covers how.
- Vented: keep a clear channel. A vented cathedral ceiling needs a continuous air space above the insulation, open from the soffit vents to the ridge vent, in every rafter bay. Skylights and hips interrupt it, so plan around them.
- Unvented: it is a design, not a shortcut. Spray foam against the roof deck can make an unvented assembly, but the designer specifies it and it gets checked.
- Count the framing. A rafter roof with batts has the same problem as a stud wall: the wood bridges the insulation. SB-12 lets a design meet either the nominal or the effective value, and your designer needs to know which one the ceiling is meeting.
The shingles, underlayment and ridge vent are on the roofing pages.
Questions people ask
Are trusses cheaper than rafters?
Almost always for an ordinary roof. Trusses are about $5.00 to $9.00 a foot of span delivered, and a crew sets them in a day. Rafters are cut on site, which is mostly labour; nobody publishes a rafter roof price, so get both quoted on the same drawings.
Can I have a cathedral ceiling with trusses?
Yes, with scissor trusses. The ceiling slopes at a lower pitch than the roof, and no ridge beam is needed. A full-pitch cathedral ceiling usually means rafters and a structural ridge beam.
Do rafters need a ridge beam?
Rafters with ceiling joists or ties across the bottom can use a plain ridge board. Without ties, as in a cathedral ceiling, the ridge must be a structural beam sized by engineered software or an engineer, with posts carried down to footings.
Can I use my truss attic for storage?
Not much. The webs are in the way and the bottom chord is designed for a ceiling, not boxes. If you want storage or a room, order room-in-attic trusses designed for that load.
Why does my cathedral ceiling drip in winter?
Usually warm, moist house air leaking into the roof and freezing on the cold deck, then melting. Air sealing the ceiling, and a clear vent channel in a vented design, are the cures.
Price the roof frame both ways
The house framing cost calculator gives you the frame by floor area and shape, with a truss package and crane estimate. If you have quotes for trusses and for a framed roof, the $99 review reads up to three of them and tells you whether they priced the same roof. More floor and roof subjects are on the floors and roof framing hub.
Sources and further reading
- Residential building permit requirements (Clarington): truss shop drawings sealed by a Professional Engineer, and when professional design is needed outside Part 9.
- The 2024 Ontario Building Code: Ontario on the 2024 Code: in force January 1, 2025, and harmonized with the national codes.
- OBOA: effective R-values under SB-12: why a design can meet either the nominal or the effective R-value, and what continuous insulation is for.
