Cantilever racking stores long, bulky or awkward loads such as timber, steel bar, pipe, sheet materials and doors on arms that project from a line of columns, with no front uprights in the way. Size it from the length of the load (which sets the number and spacing of columns), its depth (which sets arm length) and its weight per arm, and choose galvanised racking designed for wind and snow when it will stand outdoors.

This guide covers where cantilever racking works best, how to size it step by step, and what changes when it moves from a warehouse into an open yard.

What is cantilever racking used for?

Cantilever racking is used wherever goods are too long, too flexible or too irregular for pallet racking. Typical users include builders merchants and timber yards, steel stockholders, plastics and pipe distributors, window and door makers, and furniture and panel stores. Because the front of each level is open, a forklift or sideloader can place a 6 m bundle without threading it between uprights.

A cantilever run is built from a few components:

• Columns, the vertical members that carry all the arms on one or both sides.
• Bases, the horizontal feet that resist overturning and are fixed to the floor.
• Arms, which hold the load and are usually adjustable in height.
• Bracing between columns, which keeps the run stable along its length.
• Arm end stops that stop round or loose loads rolling off.

Single-sided racks stand against a wall or fence and are loaded from one side. Double-sided racks have arms on both faces and suit the middle of a building or yard. Our cantilever racking range covers both.

Medium duty, heavy duty and galvanised: which type?

The right type depends on the weight per arm and where the rack will stand. The table compares the three main options we make.

Type	Typical loads	Typical setting	Finish
Medium duty	Timber lengths, plastic pipe, sheet materials, profiles	Indoor warehouses and trade counters	Powder coated
Heavy duty	Steel bar, beams, tube bundles, heavy timber packs	Steel stockholders, fabrication shops	Powder coated
Galvanised outdoor	Timber, steel and building materials in open yards	Builders merchants, yards, open-sided sheds	Hot dip galvanised

See our medium-duty cantilever racking for lighter long goods and our heavy-duty cantilever racking for steel and dense bundles. Capacities per arm and per column side are given in the load table that comes with each order.

How to size cantilever racking

Sizing starts with the load, not the rack. Measure the longest, deepest and heaviest items you will store, then work through four decisions.

1. Length sets the number of columns

The load must rest on enough arms to stop it sagging between supports. Flexible items such as thin pipe or long timber need closer arm spacing than stiff steel sections. A common rule of thumb is to keep the overhang at each end to no more than half the column spacing, so a load is supported along its length and does not tip. As a typical example, a 6 m length is often carried on three or four columns.

2. Depth sets the arm length

The arm should be at least as long as the load is deep, so nothing hangs off the front where it could be struck. Do not choose an arm much longer than needed, because a longer arm has a lower rated capacity for the same section and makes the rack deeper, which narrows the aisle.

3. Weight sets the arm and column specification

Divide the weight of each load by the number of arms that carry it. The chart shows a 1,200 kg bundle on two to five arms: on three arms each arm takes about 400 kg, provided the bundle is straight and sits evenly. Bent or banded bundles may bear on fewer arms than you expect, so allow a margin.

4. Height sets the levels and column capacity

The number of levels depends on the height of each load plus handling clearance, and on how high your trucks can safely place long loads. The column must carry the total of all arms on its side. On double-sided racking, load both sides as evenly as possible; heavy loading on one face only puts extra bending into the column and base.

Indoor or outdoor cantilever racking?

Outdoor racking needs a different finish and a different design check. A powder-coated indoor rack will corrode quickly once the coating is chipped in a wet yard. Hot dip galvanising coats the steel inside and out with zinc, and the Galvanizers Association publishes a UK and Ireland corrosion map showing how long a typical 85 µm coating lasts at different atmospheric corrosion rates (Galvanizers Association).

The map shows lower loss rates in many inland areas and higher rates near coasts and heavy industry, which is why coastal yards should check their local rate before relying on a long coating life. Our galvanised outdoor cantilever racking is made for open yards and lean-to canopies.

Wind, snow and foundations

An outdoor rack loaded with sheet material acts like a sail, and a canopy roof collects snow. BS EN 15629, the European specification standard for storage equipment, lists the site environment, including exposure to wind, snow and seismic conditions, as information the specifier must provide (BSI Knowledge, BS EN 15629). Tell your supplier the site location and whether the rack will carry a roof or cladding. The yard surface matters too: anchors need a concrete base of suitable thickness and quality, not tarmac or hardcore.

Handling equipment and aisle widths

Long loads change how much aisle you need. A counterbalance forklift carrying a 6 m bundle across its forks needs a very wide aisle to turn. Sideloaders and multidirectional trucks carry long loads lengthways, so aisles can be much narrower and more of the floor goes to storage. Decide the truck type before the rack layout, because aisle width can change the number of runs that fit. Our guide to warehouse aisle widths for each forklift type explains the trade-offs.

Design codes, inspection and safety

Cantilever racking has its own design guidance. SEMA publishes a Code of Practice for the Design and Use of Cantilever Racking Systems and the SEMA/FEM 10.2.09 code for the structural design of cantilever racking used for unit loads (SEMA). The main European pallet racking design standard, BS EN 15512:2020, specifically excludes cantilever racking from its scope (BSI Knowledge, BS EN 15512), so ask any supplier which code their cantilever design follows.

Once installed, cantilever racking should be inspected like any other storage equipment. HSE's warehousing guidance, HSG76, covers safe storage and handling in warehouses, and regular checks should look for bent arms, damaged column bases, missing end stops and loose floor fixings (HSE, HSG76). Column bases at aisle ends are the parts most often struck; our guide to rack protection explains where guards help. Display the arm and column capacities on a load notice at the end of each run.

Frequently asked questions

What is cantilever racking best used for?

Long, bulky or irregular items such as timber, steel bar, pipe, sheet materials, doors and furniture. These loads do not fit safely in pallet racking because uprights would block their length.

How far apart should cantilever columns be?

It depends on the stiffness of the load. Flexible goods need closer columns. As a typical rule of thumb, keep end overhang to no more than half the column spacing, and ask the supplier to confirm spacing for your heaviest and most flexible items.

Can cantilever racking be used outside?

Yes, if it is hot dip galvanised and designed for the site's wind and snow exposure, and anchored to a suitable concrete base. Indoor painted racking is not suitable for open yards.

Can cantilever racking have a roof?

Yes. A roof or canopy can be added to protect timber and building materials, but the extra wind and snow load must be included in the design of the columns, bases and anchors.

Sources

• SEMA: Code of Practice for the Design and Use of Cantilever Racking Systems
• SEMA: SEMA/FEM 10.2.09 The Design of Cantilever Racking
• BSI Knowledge: BS EN 15629 Specification of storage equipment
• BSI Knowledge: BS EN 15512:2020 Adjustable pallet racking systems, principles for structural design
• Galvanizers Association: Hot dip galvanizing corrosion map
• HSE: Warehousing and storage, a guide to health and safety (HSG76)