What the header above a garage door actually does
Every garage door opening carries a structural header above it, resting on jack studs on either side, that carries the load from the roof, and any floor above, down to the foundation. Framing a door-sized hole removes the vertical wall that used to carry that load straight down. The header takes over that job: it rests on the jack studs, which pass the load down to the king studs, the foundation wall, and the footing below.
For how king studs, jack studs, and the header work together in a standard rough opening, and the exact finished-opening dimensions for common door sizes, see the rough opening size chart.
LVL vs. glulam vs. steel: how the three compare
Directional differences only. Which beam type an opening actually needs, and its exact size, is an engineering calculation for your specific span and loads — this table compares tendencies, not a substitute for a stamped design.
| Beam type | Span capability | Typical depth | Cost tendency | When it's typically specified |
|---|---|---|---|---|
| LVL (laminated veneer lumber) | Covers most standard residential garage door spans | Moderate — similar to a conventional built-up lumber header | Usually the most economical of the three engineered options | Default pick for single and double garage headers under typical loads |
| Glulam (glue-laminated timber) | Similar range to LVL, sometimes extended further | Similar to LVL, occasionally deeper for exposed applications | Comparable to LVL, sometimes a premium for appearance-grade stock | Chosen for exposed beams, or by regional supplier or engineer preference |
| Steel (W-beam or steel flitch) | Handles the longest spans and heaviest loads of the three | Can run shallower than wood for an equivalent span — useful where headroom is tight | Typically the highest material and install cost of the three | Specified when loads or headroom clearance rule out an engineered wood beam |
None of these figures are a substitute for an engineer's calculation. The right beam type and its exact dimensions depend on your specific span, loads, and local code requirements — always confirmed by a licensed structural engineer.
The 4x rule: why a wider opening needs a bigger beam
Bending demand on a header does not rise in a straight line with the span; it rises roughly with the square of the span. Take an 8-ft single opening out to a 16-ft double and the header needs to resist on the order of four times the bending demand, before any load from a room above adds weight of its own. That is why a wider opening almost always means swapping a standard lumber header for an engineered beam, not simply cutting a bigger hole and using a longer piece of the same lumber.
Lintel vs. header: not the same thing on a brick house
A steel lintel carries the brick veneer above the opening; the header, or engineered beam, carries the structural load of the wall and roof behind it. On a brick home, both exist above the same opening, doing different jobs.
The header sits inside the wall framing and carries the actual structural load, sized by the engineer. The lintel sits in the brick veneer itself, a separate steel angle that just holds up the brick coursing above the opening, so the brick doesn't rely on the wood framing behind it. Widening an opening means both get replaced and resized: a new engineered beam behind the wall, and a new one-piece steel lintel across the brick.
Why wide GTA openings need a P.Eng-stamped design and a permit
Any garage door opening past roughly 10 feet of span, or any opening beneath a load-bearing wall, needs an engineered beam design stamped by a licensed Professional Engineer (P.Eng) in Ontario, filed with a municipal building permit. The stamped drawings are what a building department reviews before issuing the permit, and what the inspector checks the finished beam against.
Skipping this step on structural work risks a stop-work order, resale disclosure problems, and insurance complications down the line. See how the permit process works, municipality by municipality, on the Ontario garage door permit guide.
Can you frame a garage door opening yourself?
Framing a single, non-structural garage door opening is straightforward carpentry a competent DIYer can handle. Anything load-bearing, or any opening wider than standard, is engineered work, not a weekend project. The dividing line is the header, not the drywall or trim.
A like-for-like door swap in an existing opening, with no change to the header, typically needs no permit and no engineer. The moment the header changes size, or the opening gets wider — such as combining two single doors into one, see centre post removal— Ontario's permit process requires stamped engineering drawings before a municipality will sign off, which puts the design step out of DIY reach regardless of how good your framing is. See the full two-single-doors-to-one process on the conversion hub.
Header and beam questions, answered plainly
What size header do I need for a 16-foot garage door?
It depends on the loads above the opening, not just the width, so there is no single answer without an engineer's calculation. A structural engineer sizes the beam for your specific span, roof and floor loads, and local snow load; typical solutions for a 16-foot double garage door are a multi-ply LVL beam or a steel beam, confirmed at the structural assessment. .
LVL vs steel: which is better for a garage door header?
Neither is universally better; the engineer picks based on span, load, and available depth. LVL is usually the more economical choice and covers most residential garage door spans. Steel gets specified when the span, the load, or a tight headroom clearance rules out an engineered wood beam. .
What is a garage door lintel?
A lintel is the steel angle that carries the brick veneer above a garage door opening, separate from the structural header behind the wall framing. On a brick home, the header carries the building's load and the lintel carries the brick; widening an opening means resizing and replacing both. .
Can I frame a garage door opening myself?
A single, non-structural opening with no change to the existing header is straightforward carpentry. Anything load-bearing, or any opening wider than what's already there, is engineered work: Ontario's permit process requires stamped structural drawings before the framing can be signed off. .
Do I need an engineer for a garage door opening?
Yes, if the opening is getting wider, the header is changing size, or anything load-bearing sits above it. A licensed structural engineer calculates the beam for the span and loads and stamps the drawings the municipality requires for the permit. A like-for-like door swap in an unchanged opening does not need one. .
What happens if the header is undersized?
An undersized header can deflect, crack finishes above the opening, or in a serious case fail under load, and it will not pass a building inspection. This is exactly what the engineered beam calculation and the municipal inspection are there to prevent, which is why sizing is never guessed at on structural work. .
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