Steel storage and shelter structures

A steel storage or shelter structure is a framed canopy or enclosure built from structural steel sections, usually S235JR or S355J2 to EN 10025-2, protected by hot-dip galvanising and fabricated under EN 1090-1, that carries a roof over vehicles, equipment or stored goods. Steel is chosen for these structures because it spans wide openings on slim members, carries heavy roof and snow loads, and galvanises to a decades-long service life. This guide covers the grades and sections, the corrosion protection, the fabrication standard, the spans and foundations, and how Eurocode loading sizes the frame.

What steel storage and shelter structures are

The family covers open and part-clad framed structures: carports over vehicles, canopies over loading bays, lean-to shelters against a wall, and open storage frames for pallets, machinery or agricultural stock. All share the same skeleton of steel columns and beams on foundations, carrying purlins and a roof, and differ mainly in how much of the frame is clad. Because the frame does the structural work, the same engineering underpins a simple car canopy and a larger storage shelter. For the roofed vehicle version see our page on steel and aluminium carports.

Why steel for open structures

Steel earns its place in these structures on stiffness and span. It has roughly three times the stiffness of aluminium, so a steel frame carries heavy snow and equipment loads across wide bays on smaller sections, which matters when a canopy has to clear vehicles or a storage bay has to stay column-free. Steel is also the most cost-effective way to buy load-bearing capacity, and once hot-dip galvanised it resists corrosion outdoors for decades. Where light weight and zero maintenance outweigh raw span, aluminium takes over, which is why many structures mix a steel frame with aluminium roof and cladding profiles.

Structural steel grades: S235JR and S355J2

The load-bearing frame is built from non-alloy structural steel to EN 10025-2, in grades S235JR and S355J2. The number is the minimum yield strength in megapascals, so S235 yields at 235 MPa and S355 at 355 MPa, and the higher grade lets a longer span or a heavier load be carried on the same section. The letters give the impact toughness: JR is tested at room temperature and J2 down to minus 20 degrees Celsius, which suits exposed outdoor frames in colder regions. ULAMEX uses S235JR or S355J2 for the load-bearing structure of its carports. For the grade detail see our guide to structural steel S235JR, S275JR and S355J2.

Sections used in the frame

A steel shelter uses a handful of section families. Open I and H sections, such as IPE, HEA and HEB beams, carry the main columns and roof beams where bending strength matters. Hollow sections, the square and rectangular tubes to EN 10219, give equal strength in both directions and a clean closed face, which suits columns and exposed members. Cold-formed C and Z purlins span between the roof beams to carry the cladding. Angles and flats brace and connect the frame. Choosing the right family for each member keeps the structure efficient. For the closed sections see our guide to EN 10219 hollow sections, and for beams see black steel structural sections.

Corrosion protection: galvanising and coatings

An outdoor steel frame is only as durable as its coating. Hot-dip galvanising to EN ISO 1461 immerses the fabricated steel in molten zinc, forming a metallurgically bonded coating that both shields the steel and sacrificially protects any small scratch, typically 45 to 85 microns thick depending on section thickness. Magnelis ZM310, a zinc-aluminium-magnesium coating, is an alternative that ULAMEX specifies for carport corrosion protection and gives strong performance including on cut edges. A powder-coated colour can be applied over the zinc for a duplex system that lasts longer still. For the zinc coatings in detail see our guide to galvanised steel and DX51D.

Fabrication to EN 1090-1

A load-bearing steel structure sold in Europe must carry CE marking under EN 1090-1, with the fabrication done to a declared execution class. ULAMEX manufactures under EN 1090-1 EXC2 and welds to ISO 3834-2, so the frames are cut, drilled, welded and coated to a controlled and documented standard rather than improvised. This matters because the strength of a frame lives in its connections as much as its members, and a certified weld and a correctly detailed base plate are what let the calculated loads actually flow to the ground. Material documentation, including 3.1 certificates, is available on request.

Spans, bays and modular assembly

Storage and shelter structures are built to a repeating bay, so a long canopy is a row of identical spans rather than one giant frame. This keeps fabrication simple, lets the structure be extended later, and matches the material to the load. The ULAMEX carport system, for example, allows up to five spans to be joined without an expansion gap, with a gutter system built in to keep the structure watertight. Sizing the bay to what the beam and purlin sections can carry, and adding structure where a span grows, keeps the roof flat and the deflection within limits.

Roof, cladding and drainage

The roof does two jobs: it carries the environmental load and it keeps the weather out. Trapezoidal steel sheet, sandwich panels or aluminium profiles span the purlins to form the roof surface, and ULAMEX uses EN AW-6060 T6 aluminium for its carport roof and cladding profiles, which stay light and corrosion-free at the exposed skin. A gutter and downpipe system carries rainwater away so it does not pool on the structure or wash around the foundations. On a solar carport the roof plane also carries the photovoltaic modules, which turns the shelter into a generating surface.

Foundations and base plates

The frame transfers everything it carries into the ground through its columns, so the base detail is critical. Each column ends in a welded base plate, bolted to a concrete foundation sized to resist the downward load, the wind uplift and the overturning moment. In colder parts of continental Europe the foundation reaches below the local frost line so that freezing ground water cannot heave it. The foundation size and the holding-down bolt pattern are set by the calculated loads for the site, which is why they are engineered per project rather than taken from a fixed table.

Wind and snow loading

The loads a shelter must resist come from the Eurocode: EN 1991-1-3 for snow and EN 1991-1-4 for wind, applied for the specific location and exposure. Snow load can dominate a large flat or low-pitch roof in continental and mountain regions, while wind uplift governs light, open canopies. Because these loads vary widely across Europe, the section sizes, the bracing and the foundations are all calculated for the actual site rather than assumed. Getting the loads right before fabrication is what separates a shelter that stands through a heavy winter from one that does not.

Steel versus aluminium for the structure

The two metals split the job. Steel carries the load: it is stiffer, spans further and is more economical for the primary frame, which is why columns and beams are steel. Aluminium handles the skin and the light members: it does not rust, needs no maintenance and stays light, which is why roof and cladding profiles are often aluminium. A well-designed shelter uses each where it is strongest, a galvanised steel frame carrying aluminium roof profiles, rather than forcing one metal to do both jobs. ULAMEX supplies both material lines, so a structure can be specified with the optimal balance of strength, weight and cost.

Where steel storage and shelter structures are used

The same framed principle covers a wide range of everyday structures. Vehicle carports and canopies shelter cars, fleets and machinery, and on a solar carport the roof also carries photovoltaic modules. Loading-bay and entrance canopies keep goods and people dry at the face of a building. Open storage frames and lean-to shelters hold pallets, timber, feed or equipment on industrial, agricultural and municipal sites, where a column-free bay matters. Smaller versions serve as bin and waste enclosures, cycle shelters and covered walkways. Larger clad frames extend the same principle to covered storage and working areas where a full enclosed building is not needed. In each case the choice of grade, section and coating follows the load, the span and the exposure, so a light garden carport and a heavy agricultural shelter are the same engineering scaled to the job.

Steel structures and material from ULAMEX

ULAMEX has supplied the metals and structures trade since 1988 and manufactures under EN 1090-1 EXC2 and ISO 3834-2.

Planning a shelter or storage structure? Send the span, layout, cladding and the site location, and ULAMEX will supply the structural steel and can fabricate the frame to your drawing, returning a non-binding quotation with lead time and availability. See our page on steel and aluminium carports, our guides to black steel structural sections and galvanised steel, or view our supply capabilities. Contact the export desk at [email protected] or +48 504 424 761.

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