Brett Field
A lintel is the beam across the top of a window or door opening. It carries the wall, roof or floor above, so that weight goes around the opening and down the frame either side, not onto the window or door.
Below is what a lintel does, how it differs from a header, what lintels are made of, how their size is worked out, when you need an engineer and approval, and the signs one is failing. These are published figures from timber and steel lintel makers and the QBCC, checked on 10 November 2026. They are a guide, not a design for your home. An engineer or certifier signs off the real job.
What does a lintel do?
It bridges the gap in the wall, carrying the load above across to the framing either side of the opening.
In a timber-framed wall, the lintel sits across the top of the opening and is held up by the framing either side. Timber maker Hyne says lintels must be used together with top plates, ledgers and head trimmers, as set out in AS 1684, the timber framing code. The bigger the opening and the more roof or floor above it, the deeper the lintel has to be.
A brick home has a second lintel for the bricks. Steel lintel maker Galintel makes galvanised steel lintels to hold up brickwork over openings, in both double brick and brick veneer walls. It says the bricks, mortar and steel work together as one beam, and that the Building Code of Australia needs at least three courses of brick above a steel lintel to form an arch effect.
Is a lintel the same as a header?
Mostly, yes. Both words are used for the beam over an opening. Sparky's cost guide uses them together, "a new lintel or header beam", when it talks about widening an opening.
Australian span tables, such as Hyne's, use the word "lintel". You may also see a head trimmer listed with it. Hyne's span table lists lintels, top plates, ledgers and head trimmers as separate parts that go in together under AS 1684, so a plan or a quote may name each one.
What are lintels made of?
Timber in most timber-framed houses, and galvanised steel under brickwork. Here are the common types:
| Material | What it is | Source |
|---|---|---|
| Sawn pine | Structural pine such as MGP10. Porta lists lintels as one use for its MGP10 | Porta |
| Sawn hardwood | Comes in higher stress grades than pine. Seasoned spotted gum, for example, is graded F17 to F34 | Business Queensland |
| Glulam (glued laminated timber) | Layers of timber glued into a deep beam. Hyne publishes upper lintel tables for its Beam LGL and Beam 15 | Hyne |
| LVL | Laminated veneer lumber, an engineered beam made from thin layers of veneer, with makers' own lintel tables | Dindas |
| Galvanised steel | Steel angles and T-bars that hold up brickwork. Galintel's are hot-dip galvanised to AS/NZS 4680 | Galintel |
What the stress grade means for pine, and the difference between MGP10, MGP12 and F7, is in our guide to what MGP10 is.
Near the beach, steel needs more care. Galintel says its lintels suit coastal and severe sites, but extra coatings may be needed there, as set out in AS 2312. It also says any cut end must be cleaned, primed and given two coats of zinc-rich paint.
What size lintel does a window or door need?
It depends on how wide the opening is, how much roof or floor sits on that wall, the roof's weight, the wind on your site and the timber. The size is read off a span table or worked out by an engineer, not guessed.
Here are sample rows from Hyne's upper lintel span table for its Beam LGL glulam. Roof load width is the width of roof that rests on that wall.
| Hyne Beam LGL lintel | Max span, roof load width 1.8 m | Max span, roof load width 3.0 m |
|---|---|---|
| 130 x 44 mm | 2,700 mm | 2,300 mm |
| 200 x 44 mm | 3,800 mm | 3,400 mm |
| 240 x 44 mm | 4,300 mm | 3,900 mm |
| 300 x 44 mm | 5,100 mm | 4,500 mm |
| 360 x 44 mm | 5,800 mm | 5,200 mm |
That table only works for its own conditions: a single span, a sheet metal roof (20 kg per m2) at a 25 degree pitch, a 10 mm plasterboard ceiling, wind class N2 and timber kept inside and dry. It limits sag to the span divided by 300, or 10 mm. A tiled roof, a higher wind class, a floor above or a wider roof load width all change the answer.
Hyne says simple house framing can be sized from the span tables in AS 1684, and more complex loads through its Hyne Design software. So treat these rows as a picture of how size and span relate. Your engineer or certifier has the final word on the lintel for your opening.
Do you need an engineer or approval to widen an opening?
If the wall is load bearing, yes to both, in most cases. Sparky's cost guide says widening a doorway means taking out part of the wall and fitting a new lintel or header beam. If the wall is load bearing, it says you need a structural engineer's design and a building permit before work starts.
- Check the wall first. Our guide on how to tell if a wall is load bearing covers the signs. Only an engineer can confirm it.
- Approval. The City of Gold Coast says minor repairs are exempt from approval only if they do not affect the structure or fire safety of the building. On the Gold Coast, approval usually comes from a private building certifier.
- Licences. The QBCC says building work valued over $3,300 needs a licensed contractor, and building design needs a licence at any value.
- Steel lintels. Galintel says your design engineer should choose the type, size and length of a steel lintel for brickwork.
Most often this comes up when a window becomes a door, or a door gets wider. The lintel and making good can be a big part of the cost. Our guides to window replacement cost and sliding door installation cost show what that adds.
What are the signs of a failing lintel?
Cracks in the wall above the opening, and a door or window that starts to stick, are the usual first signs. On brick homes, rust on the steel lintel is another. Here is how the QBCC grades wall cracks, in its Standards and Tolerances Guide:
| QBCC damage category | Crack width | What it looks like |
|---|---|---|
| 1, very slight | Under 1 mm | Fine cracks that do not need repair |
| 2, slight | Under 5 mm | Cracks easily filled. Doors and windows stick slightly |
| 3, moderate | 5 to 15 mm | Doors and windows stick. Weather tightness often impaired |
| 4, severe | 15 to 25 mm | Walls broken out and replaced, especially over doors and windows. Frames distort |
The QBCC guide says category 3 or worse is a defect that needs investigating and fixing. That table comes from the slab and footing standard, so the same cracks can also mean the footings have moved. Either way, get it looked at.
Other signs to look for:
- Rust on a steel lintel, or bricks pushed up or cracked above it. Galintel says galvanising almost removes brick cracking caused by rust pushing the bricks apart, and that corrosion often starts at the ends.
- A dip in the head of the opening, where the top of the frame is no longer straight.
We frame new door and window openings and fit new doors and windows across the Gold Coast. For a load-bearing wall, we work from a structural engineer's design, and the right licensed trades do the beam work. We do not size lintels: the engineer does. Brett holds QBCC licence 15316127, and the QBCC carpentry class covers installing windows and doors, including the framing. See our carpentry page for the work we do.
Where do these figures come from?
Checked on 10 November 2026: Hyne Timber, Common product span tables (page dated 1 May 2023) and its Upper Lintel span table for Beam LGL (version 5, revised August 2025); Galintel Steel Lintels Product Guide (InfraBuild, 2019); Dindas, LVL 13.2 Span Tables Design Guide (2025); Sparky, Door and window costs (published 1 March 2026); Porta, Structaframe MGP10 (undated); Business Queensland, Spotted gum (updated 17 May 2021); City of Gold Coast, Do your building works need approval (undated); and the QBCC's Standards and Tolerances Guide (December 2023, valid from 1 May 2023) and its pages on who must hold a licence (16 April 2026) and the carpentry licence class (30 August 2021). We will check these figures again every three months.
See our carpentry work, or check what your job will cost.
