IPE Beams: The Complete Guide (EN 10365)

The IPE is Europe's default hot-rolled I-beam: a doubly symmetric section with a slender web and two parallel-faced flanges. The name comes from the French I Profil Européen, and the family's dimensions are catalogued in EN 10365, the standard that consolidated the older Euronorm dimension sheets into a single reference for hot-rolled sections.

The parallel flanges are what separate IPE from its predecessor, the IPN, whose inner flange faces are tapered. Flat, parallel faces make bolted and welded connections far simpler (no tapered washers, no machining), which is a large part of why IPE displaced IPN as the everyday beam of European construction.

Because every mill rolls to the same catalogue, an IPE 200 ordered in Prague is interchangeable with one ordered in Madrid. That universality is the family's quiet superpower: designers, fabricators and stockholders all speak the same language. Browse the whole series at the IPE family page.

An IPE designation is simply its nominal depth in millimetres: the series runs from IPE 80 up to IPE 600. Two rules give the family its character.

• Narrow flanges: the flange width is roughly half the depth (b ≈ h/2). Material is concentrated in two thin flanges held far apart by a slender web, exactly where it works hardest in bending about the strong axis.
• Widening steps: the size increments grow with depth. Small sizes step finely so light-duty designs aren't forced to over-order; deep sizes step coarsely because a modest depth change there already shifts capacity substantially.

The full table below lists every size. Read it left to right: the geometry block (depth, flange width, web and flange thickness, root radius), then area and mass per metre, then the stiffness and strength block: second moments of area I_y and I_z, elastic and plastic section moduli, and radii of gyration for both axes, plus torsion and warping constants. Each row links to a dedicated profile page with all derived properties.

IPE is a bending specialist. Its proportions maximise strong-axis section modulus per kilogram of steel, which makes it the natural first choice wherever a member spans horizontally and carries gravity load:

• Floor beams and joists: primary and secondary members in steel and composite floors; mid-range sizes such as IPE 270 or IPE 300 are ubiquitous here.
• Purlins and side rails: roof and wall members in industrial halls, provided the roof pitch keeps the weak-axis load component small or sag rods carry it away.
• Lintels and trimmers: openings in masonry are classic territory for compact sizes like IPE 160 and IPE 200.

A second advantage is plastic reserve. Because so much of the area sits in the flanges, the plastic section modulus exceeds the elastic one by a healthy margin (the shape factor tabulated below), and most IPE sizes qualify for plastic design in the right steel grade.

The same narrow-flange logic that makes IPE efficient in bending makes it weak elsewhere.

• Columns: the weak-axis second moment of area is a small fraction of the strong-axis value, so an unbraced IPE column buckles sideways long before its cross-section is fully used. Wide-flange HEA and HEB sections, with flanges about as wide as the section is deep, are built for that job. See the comparison IPE vs HEA vs HEB.
• Torsion: as a thin-walled open section, an IPE has very little St Venant torsional stiffness. It resists twist mainly through warping of the flanges, which depends on end restraint and fades on long members. Eccentric or twisting loads call for hollow sections instead.
• Biaxial bending: significant weak-axis load (crane surge, steeply pitched roofs without sag rods) quickly erodes the strong-axis advantage.

The torsion constant I_t and warping constant I_w for every size are collected here:

The governing failure mode for a slender IPE in bending is often not the cross-section at all: it is lateral-torsional buckling (LTB): the compression flange, behaving like a slender column loaded along its length, deflects sideways and the whole beam rolls over. Narrow flanges and low torsional stiffness make IPE more LTB-sensitive than wide-flange families, so the bracing strategy is part of the design, not an afterthought.

Good practice:

• Restrain the compression flange. A concrete slab, properly fixed composite decking, or closely spaced secondary beams restrain it continuously or at short intervals, often eliminating LTB altogether.
• Mind which flange is in compression. Over the internal supports of continuous beams and along cantilevers the bottom flange is compressed: brace it with fly braces or stiffened connections; the slab above does not help there.
• Watch destabilising loads. Loads applied on top of an unrestrained top flange make buckling worse; loads hung from the bottom flange are stabilising.

In Eurocode terms, verification follows EN 1993-1-1: a reduction factor is applied to the bending resistance based on the slenderness of the unbraced segment. Shortening the unbraced length is almost always cheaper than deepening the beam.

EN 10365 defines only the geometry; the steel itself is ordered separately, most often to EN 10025-2 for non-alloy structural grades. The workhorses are S235, S275 and S355: the digits denote the nominal yield strength, and suffixes such as JR, J0 or J2 grade the impact toughness (choose tougher variants for low temperatures, dynamic loading, or weld-critical details). S355 has become the default across much of Europe: its cost premium over S235 is modest, and strength-governed designs come out lighter. When deflection or vibration governs (common for long, shallow floor beams), a stronger grade buys nothing, because the elastic modulus is identical for all grades.

Rolling accuracy is covered by EN 10034, which sets tolerances on depth, flange width, web and flange thickness, out-of-squareness of flanges, web off-centre, straightness and mass per metre. Tabulated section properties are nominal; the standard's mass tolerance tells you how far a delivered beam may legitimately deviate. For ordinary building work these tolerances are comfortably absorbed by design factors, but they matter for machined connections, tight architectural detailing, and disputes over delivered weight.