S235, S275, S355 — How to Choose the Right Steel for Your Project?

Three designations, completely different applications. S235 for light structures, S355 for heavy spans. Here's a concrete guide.

S235, S275, S355 — these three designations determine which steel is in your hall, bridge, or tower. The difference in stress capacity is enormous, but the price per kilogram is nearly identical. Choosing the wrong grade can cost 20-30% more steel or compromise structural safety.

Here's a practical engineering guide — no theory, just real-world application.

What does the "S" and number mean?

S = structural steel. Number = minimum yield strength fy in N/mm² for thickness up to 16 mm. This is the stress at which steel starts to plastically deform — the key parameter for structural calculation under Eurocode 3.

Yield strength fy (N/mm²)

S235Fences, ladders, platforms235 N/mm²

S275Beams, columns, smaller halls275 N/mm²

S355Halls, bridges, 5G towers355 N/mm²

Quick property comparison

Property	S235	S275	S355
fy (≤16 mm)	235 N/mm²	275 N/mm²	355 N/mm²
fu (tensile strength)	360-510 N/mm²	430-580 N/mm²	470-630 N/mm²
Weldability	Excellent	Excellent	Good (preheat for C)
Standard	EN 10025-2	EN 10025-2	EN 10025-2
Price/kg (relative)	◆	◆	◆ (identical!)
Weight for same span	◆◆◆◆ More	◆◆◆ Medium	◆◆ Less

◆Key insight: Price per kilogram is nearly identical for all three grades. But S355 requires 30-40% LESS material for the same span — meaning lower total cost for longer spans. An investor choosing S235 for a 30m hall pays more, not less.

When to use which steel?

Project	Recommended grade	Why
Fence, platform, ladder	S235	Simple loading, excellent weldability
Canopy up to 15m span	S235-S275	Short spans, low loads
Office building frame	S275	Good weight/strength balance
Industrial hall 20-35m	S355	Long spans, optimal mass
High hall with crane runway	S355	Dynamic loads, slenderness
5G tower, slender monopole	S355-S460	High slenderness, wind loads
Bridge, crane runway	S355 EX	Fatigue, cyclic loading

Suffixes on mill certificates — what do "JR", "J0", "J2" mean?

Suffixes indicate toughness (impact energy) at low temperatures per EN 10025:

Suffix	Test temperature	Min. toughness	Application
JR	+20°C	27 J	Interior structures, heated spaces
J0	0°C	27 J	Exterior structures, temperate climate
J2	-20°C	27 J	Cold regions, coastal areas, depots
K2 / M / N	-20°C	40 J	Demanding applications, full penetration welds

▲For Central Europe: Exterior structures require minimum J0. For coastal and mountain locations, we recommend J2. Rakušić delivers S355J2 as standard on all halls and towers — not J0 as the minimum.

Need a concrete quote?

3D blueprint on your desk — tomorrow morning. Let's talk.

Learn more →