Anchoring pallet racking: floors and fixings
Anchoring pallet racking: floors and fixings
Pallet racking used with forklifts should be fixed to the floor through every upright footplate, using the anchors the racking designer specifies, into a concrete slab that can carry the loads. SEMA's design code, as explained in a SEMA technical column, requires all uprights in racking used with mechanical handling equipment to be floor fixed, with each connection able to transfer at least 3 kN tension and 5 kN shear (un-factored).
Anchoring is a small part of an installation by cost, but it is where the racking design meets your building. This guide covers why fixings matter, what the slab must provide, which anchors are used, how shims and levelling affect them, which floors need extra care and how to keep anchors sound in service.
Key takeaways
- Fix every upright footplate in racking served by forklifts, unless your designer's calculations say otherwise.
- The slab, not the anchor, is often the limit: check thickness, concrete strength, joints and edges before setting out.
- Use the anchor type, size and embedment on the design, and install to the anchor maker's torque.
- Post-tensioned, heated and coated floors need checks before anyone drills.
- Loose or missing anchors are a defect; include them in every inspection.
Why does racking need anchoring?
Anchors hold the base of each upright in place against horizontal forces. Those forces come from pallets being placed and pulled, trucks nudging frames, and the small out-of-plumb that every structure has. The design standard EN 15512 sets the principles for the structural design of adjustable pallet racking, including how these actions are taken into account (BSI, BS EN 15512). Without fixings, a footplate can be pushed sideways by a truck strike, which bends the upright above it and moves the whole frame out of line.
Anchors also keep racking from lifting or sliding where frames are tall and narrow relative to their depth. Fixing to the building instead is generally not desirable: building designers rarely accept racking loads on their structure, and racking is not designed for the wind and snow loads the building carries (Warehouse and Logistics News, SEMA technical column, 2014).
What does SEMA's design code ask for?
SEMA's older design code required fixings at perimeter uprights that trucks could reach, and at all uprights once the height-to-depth ratio passed set limits. Its newer code states that all uprights in racking for use with mechanical handling equipment shall be floor fixed, each connection transferring a minimum un-factored force of 3 kN in tension and 5 kN in shear (Warehouse and Logistics News, SEMA technical column, 2014). SEMA has also noted that older installations built to earlier code revisions need not generally be retrofitted, and that the number of fixings per baseplate is at the supplier's discretion, typically one, sometimes two (Warehouse and Logistics News, SEMA technical column, 2014).
SEMA codes are not law, but they are widely treated as the accepted standard for UK racking. Our designs fix every footplate, and the anchor specification appears on the layout drawing.
What does the floor have to provide?
The floor has to carry concentrated loads through small footplates and hold anchors securely. The Concrete Society's TR34 is the widely used UK guide to the design and construction of concrete industrial ground floors (Concrete Society, TR34), and a floor engineer can check an existing slab against the racking loads.
The worked example shows how quickly the load on a single footplate grows as beam levels are added. That load has to spread through the slab without cracking it, which depends on slab thickness, concrete strength, the sub-base and how close the footplate sits to a joint or the edge of the slab.
A larger footplate spreads the same load over more concrete. Footplate size is part of the frame design, so it is one of the things to compare between quotes. Our pallet racking upright frames page lists the footplate options for each upright section.
Floor information we ask for
- slab thickness and concrete grade, from drawings or a core test;
- positions of saw cuts, construction joints and slab edges;
- any underfloor heating, cooling or services;
- whether the slab is post-tensioned;
- floor flatness in the racking zone, especially for narrow-aisle trucks.
Which anchors are used for racking?
Most racking is fixed with mechanical anchors into concrete. The table compares the common types; the right one for your floor is the one the designer specifies, installed to the anchor maker's instructions.
| Anchor type | How it holds | Typical racking use | Watch points |
|---|---|---|---|
| Through-bolt (wedge) anchor | Expansion clip grips the hole as the nut is torqued | Standard footplate fixing in sound concrete | Needs correct hole depth and torque; edge distance matters |
| Sleeve anchor | Sleeve expands along its length | Lighter frames and accessories | Lower capacity than wedge anchors in many sizes |
| Concrete screw anchor | Thread cuts into the concrete | Removable fixings, reconfigurable layouts | Hole cleaning and drill bit size are critical |
| Resin (chemical) anchor | Bonded stud in a resin-filled hole | Close to edges, weaker concrete, high loads | Cure time before loading; temperature affects curing |
Typical racking fixings are M10 or M12, with one or two per footplate. Anchors are drilled through the footplate holes, the holes are cleaned of dust, and the anchor is set and torqued. If an anchor spins or will not reach torque, it is abandoned and a new hole drilled at the minimum spacing the anchor maker allows.
How do shims and levelling affect anchors?
Floors are never perfectly level, so installers pack under footplates with steel shims to bring frames plumb and beams level. BS EN 15620:2021 sets the tolerances, deformations and clearances for pallet racking production, assembly and erection (BSI, BS EN 15620:2021). Shim stacks should be the full size of the footplate, kept to the height the designer allows and fixed through by the anchor. The anchor must be long enough to reach full embedment through the plate and the shims, so a deep shim stack may need a longer anchor than the standard one. Our guide to how pallet racking is installed shows where levelling and anchoring sit in the sequence.
Which floors need extra care?
- Post-tensioned slabs: cutting a tendon is dangerous and costly. The tendons must be located by scanning or from as-built drawings before drilling.
- Heated or insulated floors: underfloor heating in cold stores, and the insulation beneath, limit anchor depth and position. Our cold store racking guide covers this in more detail.
- Screeds, asphalt and thick resin coatings: the anchor must reach the structural slab, not just the topping.
- Suspended floors and mezzanines: loads go into a structural frame or deck, so the fixing method comes from the floor's designer.
- Outdoor yards: cantilever racking outside needs a slab or pad foundation designed for it, and fixings suited to wet conditions, as with our galvanised outdoor cantilever racking.
Checking anchors in service
Anchors are part of the structure, so they are part of every inspection. BS EN 15635 covers the use, inspection and maintenance of steel storage equipment, with the aim of keeping the racking structurally sound (BSI, BS EN 15635). HSE guidance also expects racking to be erected on sound, level floors and installed by competent people (HSE, HSG76).
In practice, check for missing anchors, loose nuts, cracked concrete around footplates and footplates that have shifted after a truck strike. Any frame that has been hit hard should have its anchors checked, as an impact can loosen them even when the upright looks straight. Our racking inspection checklist includes footplates and fixings in the in-house check.
Frequently asked questions
Does every upright need an anchor?
For racking used with forklifts, SEMA's design code calls for every upright to be floor fixed. Follow your racking designer's specification, which also sets the number of anchors per footplate.
Can racking be fixed to the building wall instead of the floor?
Generally not. Building structures are rarely designed for racking loads, and racking is not designed for building wind and snow loads, so floor fixing is the standard approach.
What if the slab is too thin for the racking load?
Options include larger footplates, shorter beam spans, lower beam levels or local slab strengthening. The racking designer and a floor engineer should agree the solution together.
Do you supply the anchors with the racking?
Yes. We supply anchors and shims to suit the design, listed on the packing list, and we confirm the specification once we have your floor details.
Send us your floor details with your layout and we will size the footplates and anchors for your slab as part of the quote.
Sources
- Warehouse and Logistics News: Is this your problem? SEMA technical column (August 2014)
- Warehouse and Logistics News: Is this your problem? SEMA technical column (May 2014)
- BSI: BS EN 15512 Adjustable pallet racking systems, principles for structural design
- BSI: BS EN 15620:2021 Steel static storage systems, tolerances, deformations and clearances
- BSI: BS EN 15635 Application and maintenance of storage equipment
- Concrete Society: TR34 Concrete industrial ground floors, a guide to design and construction
- HSE: HSG76 Warehousing and storage, a guide to health and safety
