Aluminium angle is the L shaped extrusion that quietly holds half of NZ together. It corners shelving, caps the edges of cladding panels, frames cabinet doors, supports light brackets, and lines the inside of car decks, boats and trailers. Most builders, joiners and fabricators reach for it weekly and only stop to think about which one to buy when they hit a stocking shortage or a size that does not fit.
This guide is the buyer’s reference. It covers the difference between equal and unequal aluminium angle, the sizes that NZ stockists carry, the grade and finishes that show up in the trade, and how to pick the right profile for the project at hand. The aim is to remove the guess work so the order goes out right the first time.
The fast answer: If both flanges of the L are the same width, you want equal angle. If one flange is longer than the other, you want unequal angle. NZ aluminium angle is almost always extruded from 6063 T5 alloy, supplied in 3m or 5.95m lengths, with wall thicknesses from 1.1mm to 3mm. Mill finish, anodised and powder coated are the three common finishes.
What aluminium angle actually is
An aluminium angle is an L shaped extrusion: two flat flanges joined at a 90 degree corner. The profile is pushed through a die at the extrusion press and cut to length, so the cross section is identical from one end of the bar to the other. The legs of the L are usually called flanges or wings, the inside surface is the inner face, and the outside is the outer face. The radius at the corner is small but not zero, so when you fit two angles back to back there is a thin gap on the outside corner.
Aluminium angle is supplied in two families: equal angle, where the two flanges are the same length (for example 25 x 25 x 3mm), and unequal angle, where one flange is longer than the other (for example 40 x 20 x 3mm). The difference matters because each family covers a different set of jobs.
Equal vs unequal: how to tell which you need
Equal angle is the workhorse for corners, frames and brackets where the two surfaces meeting at the corner are roughly the same width. Picture frames, cabinet edges, table legs, light duty shelf supports, marine trim and shower screen frames are all equal angle jobs.
Unequal angle steps in when one surface needs to cover or support more than the other. Think of cladding edge trim where the visible face is wide and the return into the framing is short, or a benchtop edge where the top flange covers the substrate but the down stand is just deep enough to hide the edge. Stair nosing, vehicle deck edging, kitchen toe kicks and cabinet door rebates lean toward unequal angle for the same reason.
| Use case | Equal angle | Unequal angle |
|---|---|---|
| Picture frames and trim | Yes, default | Rare |
| Cladding edge cap | Sometimes | Yes, default |
| Shelf bracket and support | Yes, most cases | When wall fix face needs to be wider |
| Furniture corner brace | Yes, default | Rare |
| Cabinet door rebate | Sometimes | Yes, default |
| Stair nosing | Rare | Yes, default |
| Boat and trailer trim | Yes, default | Sometimes |
| Solar mounting | Yes, default | When rail and roof faces differ |
If you are still unsure, the simplest check is to ask which face is going to be visible. If the visible face is wider than the hidden fixing face, you want unequal angle with the wide flange facing out. If both faces are visible to a similar degree, equal angle is the better look.
Common sizes in NZ
SD Aluminium carries equal and unequal angle across the sizes that the NZ trade actually orders most often. The list below shows the size envelope. Smaller and larger sizes are available on special order.
Equal angle sizes
| Profile (mm) | Wall thickness (mm) | Typical length (m) | Typical use |
|---|---|---|---|
| 10 x 10 | 1.6 | 5.95 | Fine trim, joinery edge |
| 12 x 12 | 1.6 or 3.0 | 3.0 | Trim, small bracket |
| 15 x 15 | 1.2 | 3.0 or 5.95 | Trim, edge protection |
| 16 x 16 | 1.5 or 3.0 | 3.0 or 5.95 | Furniture, light frame |
| 19 x 19 | 1.5 or 1.9 | 3.0 or 5.95 | Furniture, cabinet |
| 20 x 20 | 1.6 or 3.0 | 3.0 or 5.95 | Frame corner, shelf, signage |
| 22 x 22 | 1.1 | 3.0 | Trim, fine frame |
| 25 x 25 | 1.5, 2.5 or 3.0 | 3.0 or 5.95 | General fabrication, brackets |
| 30 x 30 | 3.0 | 5.95 | Light structural, machine guarding |
| 40 x 40 | 3.0 | 5.95 | Light structural, deck framing |
| 50 x 50 | 3.0 | 5.95 | Light structural, transport |
The 20 x 20 x 3mm and 25 x 25 x 3mm sizes are the two most common across NZ trade orders. Almost every joiner, cabinet maker and light fabricator stocks one of these as a default. 12 x 12, 15 x 15 and 16 x 16 cover the finer joinery and trim work. 40 x 40 and above start to overlap with steel angle territory, and the trade off shifts toward strength to weight ratio.
Unequal angle sizes
| Profile (mm) | Wall thickness (mm) | Typical length (m) | Typical use |
|---|---|---|---|
| 18 x 10 | 1.0 | 3.0 | Fine trim, edging |
| 20 x 12 | 1.6 or 3.0 | 3.0 or 5.95 | Cabinet rebate, trim |
| 25 x 12 | 1.6 or 3.0 | 5.95 | Edge cap, light bracket |
| 25 x 20 | 1.6 or 3.0 | 3.0 | Cladding return, frame |
| 30 x 20 | 2.5 | 3.0 | Bench edge, light support |
| 30 x 25 | 2.0 | 3.0 | Frame corner, cabinet |
| 32 x 20 | 1.5 | 3.0 or 5.95 | Trim, edge cap |
| 32 x 25 | 3.0 | 5.95 | Frame corner, light bracket |
| 40 x 12 | 1.6 | 3.0 or 5.95 | Sign and panel edging |
| 40 x 25 | 2.0 or 3.0 | 5.95 | Stair nosing, trim |
| 50 x 25 | 3.0 | 5.95 | Stair nosing, ramp edge |
| 100 x 25 | 1.8 | 3.0 | Wide flange trim, signage |
The 25 x 20 and 30 x 20 sizes are the unequal angle workhorses for cabinet, joinery and edge cap work. 40 x 25 and 50 x 25 cover most stair nosing and ramp edge jobs. The 100 x 25 profile is a wide flange trim, often used for signage edges and shelf face caps where the visible face needs to dominate.
Lengths: 3m vs 5.95m
Most aluminium angle in NZ ships in two stock lengths. 3m is the standard joinery and trim length: it fits in most utes, can be carried by one person, and matches the cut sheet for most cabinet and furniture work. 5.95m is the standard mill bar length: it suits builders and fabricators on bigger framing jobs, balcony balustrades, transport applications and anywhere a long unbroken run avoids joins.
If the project needs a 4m run, the 5.95m bar is the right pick. Cutting a 4m piece out of a 3m bar means a join, and a join in aluminium angle weakens the corner and shows on a finished face. Order long, cut to size.
What grade and why 6063 T5
Almost all NZ aluminium angle is extruded from 6063 T5 aluminium alloy. 6063 is the alloy designation, T5 is the temper, and together they describe a metal that is easy to extrude into thin walled sections, accepts a good anodised or powder coated finish, and offers a balance between strength and workability.
A few specific points that matter for the buyer:
- Corrosion resistance: 6063 T5 has good general corrosion resistance and is suitable for indoor and most outdoor NZ environments. On coastal sites within 500m of the sea, a powder coated or anodised finish extends the life of the visible surface.
- Strength: 6063 T5 is a medium strength alloy. It is fine for frames, brackets and trim. For high load structural work, like vehicle chassis components or load bearing balustrades, 6061 T6 is the better pick and SD Aluminium can supply it on order.
- Workability: 6063 T5 cuts, drills, taps and welds cleanly with standard trade tools. It does not work harden as fast as harder alloys, so a sharp blade and a slow feed give a clean cut and a clean hole.
- Finish: The mill finish is silver and slightly matt. The metal anodises well and powder coats well, so colour matching to joinery and cladding is straightforward.
If a project spec calls for a different alloy, the most common alternatives are 6061 T6 (higher strength, used in transport and structural) and 5052 H32 (better corrosion resistance, used in marine). These are special order rather than stock, but the team can quote on a roll size or full bar basis.
Finishes
Three finishes cover the bulk of NZ aluminium angle orders.
Mill finish is the default. The extrusion arrives with a clean silver surface straight off the die. It is fine for hidden bracketry, structural work and any application where the angle is going to be painted on site or hidden inside framing.
Powder coated finishes apply a thermosetting polymer to the extrusion in a controlled oven. SD Aluminium stocks 3m angles in matt black and several mid range colours, with custom colours on special order. Powder coat suits cladding trim, joinery edges, balcony framing, and any application where the angle is visible and needs to match an existing scheme. The finish typically lasts 15 to 25 years before any noticeable wear, longer if the surface is rinsed once or twice a year on coastal sites.
Anodised finishes grow a controlled oxide layer on the aluminium surface in an electrochemical bath. Anodising preserves the metal look but increases corrosion resistance and surface hardness. It is the standard finish for high end joinery, architectural detailing and marine applications. Anodising is not a stock SD finish on standard angle, but the team can route an order through to the anodising supplier on quote.
How to cut, drill and fix aluminium angle
Cutting
Aluminium angle cuts cleanly with a mitre saw fitted with a non ferrous blade, or with a cold cut saw on production runs. A standard wood blade with carbide tips works in a pinch but leaves a rougher edge. For a hand cut, a hacksaw with a fine tooth blade gives a clean line through the smaller sizes (up to about 20 x 20 x 3mm). Clamp the work and feed slowly. Aluminium gums up if the cut runs too hot.
Drilling
Pilot the hole, then step up to the final diameter. HSS drill bits do the job, with cobalt bits a better pick for production drilling. Cutting fluid or a dab of wax keeps the swarf clear. For tapping a thread directly into the angle wall, the 3mm wall thicknesses give the best thread holding, and the 1.6mm and thinner walls are better with a riv nut or a captive nut.
Fixing
Aluminium angle screws to timber, particle board, mdf, steel and concrete with the appropriate fastener. For timber framing, stainless or zinc plated wood screws through the angle leg do the job. For steel framing, self drilling tek screws are the trade default. For concrete, a masonry anchor sized to the angle wall thickness is the right pick. Avoid mixing aluminium with bare carbon steel fasteners in coastal or wet conditions, because the dissimilar metal contact accelerates corrosion at the interface. Stainless fasteners are the safer choice in any external NZ application.
Common applications by trade
Cabinet makers and joiners use 16 x 16, 19 x 19 and 20 x 20 equal angle for door rebates, frame corners and edge caps. 25 x 12 and 30 x 20 unequal angle covers benchtop edges and cabinet door overlays.
Builders reach for 25 x 25, 40 x 40 and 50 x 50 equal angle for light structural framing, deck edge supports, balustrade framing and corner braces. 100 x 25 unequal angle shows up on cladding edge caps, parapet trim and signage backing.
Sign makers and shopfitters use 20 x 20, 25 x 25 and 100 x 25 angle for sign frames, retail fixtures and display cases. The 100 x 25 in particular is a popular wide face trim.
Marine and transport fabricators use 25 x 25 and 40 x 40 equal angle for deck framing, trim and corner protection on boats, trailers and truck decks. For coastal use, 5052 marine alloy is the better pick, available on special order.
Solar and electrical installers use 40 x 40 and 50 x 50 equal angle for panel mounting rails and bracket sets. The angles fit standard solar clamp sizes and screw through to most roofing profiles.
Aluminium angle, flat bar, channel or sheet
Aluminium angle is one option in the broader range of stock extrusions. Picking between angle and the alternatives is usually a question of shape rather than material.
| You need… | Pick this profile |
|---|---|
| A 90 degree corner support or edge cap | Equal or unequal angle |
| A flat strap, plate or fascia | Flat bar |
| A U shaped channel for trim, edges or sliders | U channel |
| A round or rectangular hollow for handrail or frame | Round tube or rectangle hollow |
| A flat panel surface (cladding, signage, fabrication) | Aluminium sheet, see the aluminium sheet grades guide |
| A structural frame compared with steel | Read steel vs aluminium box section NZ first |
Frequently asked questions
What is the standard length for aluminium angle in NZ?
Two lengths dominate. 3m is the standard joinery and trim length, suited to most cabinet and furniture work. 5.95m is the standard mill bar length, used by builders and fabricators on longer runs. Both lengths are stocked in mill finish, and most popular sizes are also stocked in 3m powder coated lengths.
What is the most common size of aluminium angle?
20 x 20 x 3mm and 25 x 25 x 3mm equal angle are the two highest volume sizes across the NZ trade. They cover the bulk of joinery, light framing and sign making jobs. In unequal angle, 25 x 20 and 30 x 20 are the most ordered profiles.
What grade is the aluminium angle that I am buying?
Standard NZ stock aluminium angle is 6063 T5 alloy. This is a medium strength alloy with good corrosion resistance and excellent workability. If a spec calls for a higher strength alloy like 6061 T6 or a marine grade like 5052, ask for a special order quote.
Can I weld aluminium angle?
Yes. 6063 T5 welds cleanly with a TIG or MIG setup using a matching 4043 or 5356 filler wire. Welded corners on aluminium angle are common on machine guards, frames and trailers. For finished or anodised work, mechanical fixing is usually neater than welding.
Does aluminium angle corrode in NZ?
Bare aluminium develops a thin oxide layer that protects the metal underneath. In normal inland NZ conditions, mill finish aluminium angle holds up for decades. Within 500m of the coast, a powder coat or anodised finish extends the surface life significantly and reduces visible salt marking. The structural metal itself does not rust the way steel does.
Can I powder coat aluminium angle after I install it?
It is possible but rarely worth it. Factory powder coating is done in a controlled oven on the bare extrusion, and the finish is more even and more durable than anything sprayed on site. Order the angle in the finish you want at the start of the project, or order mill finish and paint on site with an aluminium primer plus a top coat for short term applications.
What is the difference between aluminium angle and aluminium L bracket?
An angle is a continuous extrusion sold in long lengths. An L bracket is a short, cut to size piece, usually with pre drilled holes for fixing. The L bracket is often cut from aluminium angle and finished individually. If the project needs a one off bracket, ask for it in the right size from stock angle; if the project needs hundreds, the L bracket is the better path.
For the full size and finish range, see the equal angle product page or the unequal angle product page. The wider aluminium extrusions range sits alongside angle, flat bar, channel, tube and other standard profiles. For trade orders, special sizes or powder coat colour matching, send the cut list and finish requirement to the SD Aluminium team and the team will quote on stock plus any production order.
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