LGS Profile Sizes and Thickness Guide: C Studs, U Tracks and How to Specify Them
Light gauge steel (LGS) framing is used for houses, modular buildings, extensions, roof trusses and infill walls. Its two basic sections, the C stud and the U track, look simple, but size, thickness, steel grade and coating decide whether a frame is structural or not. This guide gives the common LGS profile sizes with weight tables, recommended thicknesses by application, the US naming system, and an ordering checklist.
• Most common LGS wall stud: C 89 × 41 mm (3.5 in web), also produced as 70, 90, 100, 140 and 150 mm.
• Typical thickness: 0.75–1.15 mm for wall framing and trusses, 1.15–2.5 mm for floor joists and heavier members.
• Typical material: high-strength G550 / S550GD steel with an AZ150 aluminium-zinc or Z275 zinc coating.
• LGS is structural framing. Drywall CW/UW profiles (about 0.6 mm) are a different, non-structural product.
What Is Light Gauge Steel Framing?
LGS framing uses cold-formed steel sections, usually 0.75 to 2.5 mm thick, to build load-bearing walls, floors and roofs. Modern LGS is produced on CNC roll-forming machines that read the building's CAD model. Each member comes off the line cut to length, with bolt holes, service holes, dimples and notches already punched, and labelled for assembly. A wall panel can be screwed together like a kit, without on-site cutting.
The result is a light, dimensionally accurate frame that does not rot, shrink or burn. LGS also reduces the load on foundations. Read how LGS components reduce construction costs in modular wall systems for the cost side.
C Studs and U Tracks: The Two Basic Sections
C stud (C section)
A web with two flanges and stiffening lips. Used for vertical studs, noggings, joists, truss chords and webs. The lips prevent the flanges from buckling.
U track (U channel)
A web with two flanges and no lips. Used as top and bottom plates of walls, rim tracks for floors and to cap the ends of joists. The stud fits inside the track.
Special sections
Furring channels, hat sections, angles and heavier C sections for headers, lintels and long-span joists complete the system.
Many CNC roll-forming systems use a single "C" profile for both studs and plates. The flanges are notched where members meet, so studs and plates nest into each other. Traditional systems use separate studs and tracks.
LGS C Stud Sizes and Weights
Dimensions are web height × flange width × lip length. Weights are theoretical, for bare steel.
| C stud, h × b × c (mm) | 0.75 mm kg/m | 0.95 mm kg/m | 1.15 mm kg/m | 1.5 mm kg/m | 2.0 mm kg/m |
|---|---|---|---|---|---|
| C 70 × 41 × 11 | 1.01 | 1.27 | 1.53 | 1.98 | 2.61 |
| C 89 × 41 × 11 | 1.12 | 1.41 | 1.70 | 2.20 | 2.90 |
| C 90 × 40 × 10 | 1.10 | 1.39 | 1.67 | 2.17 | 2.86 |
| C 100 × 41 × 11 | 1.18 | 1.49 | 1.80 | 2.33 | 3.08 |
| C 140 × 41 × 13 | 1.44 | 1.82 | 2.20 | 2.85 | 3.77 |
| C 150 × 41 × 13 | 1.50 | 1.90 | 2.29 | 2.97 | 3.92 |
| C 200 × 50 × 15 | 1.93 | 2.43 | 2.94 | 3.82 | 5.06 |
| C 250 × 50 × 15 | 2.22 | 2.81 | 3.39 | 4.40 | 5.84 |
LGS U Track Sizes and Weights
A U track is sized so that the stud fits inside it. Its inside web width equals the stud's web height.
| U track, inside web × flange (mm) | 0.75 mm kg/m | 0.95 mm kg/m | 1.15 mm kg/m | 1.5 mm kg/m | 2.0 mm kg/m |
|---|---|---|---|---|---|
| U 70 × 35 (for C 70) | 0.82 | 1.04 | 1.26 | 1.65 | 2.20 |
| U 89 × 35 (for C 89) | 0.94 | 1.19 | 1.44 | 1.87 | 2.50 |
| U 90 × 35 (for C 90) | 0.94 | 1.19 | 1.44 | 1.88 | 2.51 |
| U 100 × 35 (for C 100) | 1.00 | 1.27 | 1.53 | 2.00 | 2.67 |
| U 140 × 35 (for C 140) | 1.24 | 1.57 | 1.90 | 2.47 | 3.30 |
| U 150 × 35 (for C 150) | 1.30 | 1.64 | 1.99 | 2.59 | 3.45 |
| U 200 × 50 (for C 200) | 1.77 | 2.24 | 2.71 | 3.53 | 4.71 |
| U 250 × 50 (for C 250) | 2.06 | 2.61 | 3.16 | 4.12 | 5.49 |
Calculated from nominal dimensions (centreline method, steel density 7,850 kg/m³), without coating. An AZ150 or Z275 coating adds about 2–4% at these thicknesses. Profile dimensions vary between roll-forming systems, so confirm them with the manufacturer.
Weight Calculator
Which Thickness Do You Need?
Thickness is set by the structural design, but these ranges are typical for buildings up to three or four storeys:
| Application | Typical section | Typical thickness |
|---|---|---|
| Non-load-bearing internal walls | C 70–89 | 0.55–0.75 mm |
| Load-bearing walls, 1–2 storeys | C 89–90 | 0.75–0.95 mm |
| Load-bearing walls, 3–4 storeys or high wind | C 89–150 | 1.15–1.55 mm |
| Roof trusses | C 89 | 0.75–1.15 mm |
| Floor joists | C 150–250 | 1.15–2.5 mm |
| Headers, lintels, heavy members | C 150–300, often doubled | 1.5–2.5 mm |
Steel Grade and Coating
- High-strength steel: most LGS systems use G550 steel (AS 1397), which has a minimum yield strength of about 550 MPa, or S550GD to EN 10346. S350GD and S390GD are used for heavier sections. In the US, ASTM A1003 grades of 33 ksi and 50 ksi are common.
- Coating: AZ150 aluminium-zinc (150 g/m² total) is the standard in many LGS systems. Z275 zinc is common in Europe, and G60 / G90 in the US. Zinc-magnesium coatings are used for coastal and humid sites.
- Base metal vs total thickness: LGS thickness is usually specified as base metal thickness (BMT), without coating. Check which one a supplier quotes.
US Naming: The SSMA Designation System
In North America, cold-formed steel framing is named with the SSMA system. A designation such as 350S162-43 means:
- 350: web depth of 3.50 inches (89 mm)
- S: stud or joist section with lips (T = track, U = channel, F = furring)
- 162: flange width of 1.62 inches (41 mm)
- 43: minimum base metal thickness in mils (thousandths of an inch)
| Mils | Design thickness | Approx. metric equivalent | Typical use |
|---|---|---|---|
| 33 | 0.0346 in | 0.88 mm | Light load-bearing walls |
| 43 | 0.0451 in | 1.15 mm | Load-bearing walls, trusses |
| 54 | 0.0566 in | 1.44 mm | Heavier walls, joists |
| 68 | 0.0713 in | 1.81 mm | Joists, headers |
| 97 | 0.1017 in | 2.58 mm | Heavy joists, beams |
So a European 89 × 41 C stud in 1.15 mm is roughly comparable to a US 350S162-43, provided the steel grade is also equivalent.
LGS vs Drywall Profiles: Do Not Mix Them Up
Drywall metal profiles (CW and UW to EN 14195) have similar shapes, but they are typically about 0.6 mm thick, made from lower-strength steel and designed only to carry plasterboard. They are not structural framing. A quotation for "C and U profiles" can mean either product, so always state the application, thickness and steel grade. For roof and wall purlins, which are heavier again, see our C, Z and omega purlins guide.
How to Order LGS Profiles
- Supply type: straight lengths of profile, or CNC-manufactured panels and trusses from your design files.
- Section dimensions: web × flange × lip, for example C 89 × 41 × 11.
- Thickness as base metal thickness (BMT), and the tolerance standard.
- Steel grade and coating: for example G550 AZ150 or S550GD+Z275.
- Punching: service holes, bolt holes, dimples, notches. Agree on the file format (for example IFC, or the roll-former's native format) when you order pre-cut members.
- Lengths and labelling: cut lengths, member marks and bundling per panel or per floor.
- Accessories: self-drilling screws, hold-downs, strap bracing and brackets.
- Documents: EN 10204 3.1 coil certificates, CE marking where required, and load tables or design calculations for the system.
Sourcing LGS from Türkiye
Turkish manufacturers run CNC LGS roll-forming lines that produce pre-punched, labelled members and complete wall panels and trusses from the customer's design. They supply housing, modular and reconstruction projects in Europe, the Balkans, the Middle East and Africa. Because LGS panels are light and flat-packed, a single container can carry the frames for several houses.
See our light gauge steel C and U profiles range, or send your drawings for a quotation. Cold-formed sections and steel structures are covered by the EU CBAM, so ask for coil emissions data with your EU orders.
Frequently Asked Questions
What is the standard LGS stud size?
The most common LGS wall stud is a C section with an 89 mm web and a 41 mm flange, in 0.75 to 1.15 mm thick high-strength steel. 70, 90, 100, 140 and 150 mm webs are also widely used.
What thickness is LGS framing?
LGS framing is usually 0.75 to 1.15 mm thick for walls and roof trusses, and 1.15 to 2.5 mm for floor joists, headers and heavier members. The exact thickness comes from the structural design.
What is the difference between a C stud and a U track?
A C stud has stiffening lips on its flanges and is used for vertical studs, joists and truss members. A U track has no lips and is used as the top and bottom plate of a wall or the rim of a floor. The stud fits inside the track.
Are LGS profiles and drywall profiles the same?
No. Drywall CW and UW profiles are about 0.6 mm thick and only carry plasterboard. LGS profiles are structural members made from thicker, high-strength steel and are designed to carry building loads.
What does 350S162-43 mean?
It is a US SSMA designation for a C stud with a 3.50 inch (89 mm) web, a 1.62 inch (41 mm) flange and a base metal thickness of 43 mils (0.043 in minimum, about 1.09 mm, with a design thickness of about 1.15 mm).
What steel is used for LGS framing?
Most LGS systems use high-strength G550 or S550GD steel with an AZ150 aluminium-zinc or Z275 zinc coating. Heavier sections may use S350GD or S390GD.
Send your drawings or design files. Steeling.net returns offers from Turkish LGS manufacturers for profiles, pre-punched members, wall panels and trusses. There are no fees for buyers.
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