ECT Ratings and Load-Bearing Design for Cardboard Floor Displays in the UK 

Supplier guides quote anywhere from about 5 kg to 60 kg per shelf for a cardboard floor display. That spread makes sense once you see what an ECT rating leaves out. It measures the strength of the board, and most cardboard floor displays use board around 5.6 to 7.7 kN/m. What the finished unit carries depends on its design and on where it stands. Lab boards are tested at 50% relative humidity. UK outdoor air averages closer to 80% across the year.

This guide explains what the number means. It then covers four gaps between the lab and a UK shop floor, followed by the design moves that close them. For finished units, see our corrugated display boxes.

• How an ECT rating is measured and what the number means

• Four gaps that open between the lab and the shop floor

• The shelf, upright and base decisions that close those gaps

What Counts as a Cardboard Floor Display?

A cardboard floor display is a freestanding corrugated unit that stands on the shop floor and holds product. There are three common types. The first is the shelf unit, often called an FSDU. The second is the pallet display on a half- or quarter-pallet footprint. The third is the dump bin. Each one carries load differently. A shelf unit passes weight down its uprights. A pallet display passes it through the base and internal pillars. A dump bin holds loose stock against its walls.

What Does an ECT Rating Measure?

To measure ECT, a lab stands a small strip of corrugated board on its edge and presses down until it buckles. This is the edge crush test. ISO 3037 sets the strip at 100 mm long and 25 mm high. A reported ECT figure is the mean of ten valid strips. We ask the board mill for its ECT test report before a grade is specified.

The test loads the board along the flutes. That is the direction an upright carries weight, so ECT is a useful first screen for a load-bearing panel.

Reading kN/m and pounds per inch

UK and European suppliers quote ECT in kN/m. US suppliers quote pounds per inch. Multiply pounds per inch by 0.175 to convert. The table shows common US grades in both units.

Treat the last column as a starting point from design guides, since it does not guarantee capacity. Our guide to flute grades and ECT explained covers the board side in more detail.

The Lab Is Dry, and the UK Is Not

A lab ECT value describes board that has sat at 50% relative humidity. UK air rarely does. Unheated stockrooms and loading bays tend to follow the weather. That swing of about 20 points can push the same board from a 20% loss towards a 50% loss.

Corrugated board strength falls in damp air, because damp fibres carry less load. Industry references put the loss at about 20% at 70% humidity. At 80% it reaches 30 to 40%. At 90% it passes 50%.

Where does the display sit between delivery and installation, and for how long?

A Strip of Board Is Not a Finished Display

The strip test gives a number for the board. A floor display is cut, folded, slotted, and loaded. The box compression test ISO 12048 loads a finished structure from the top and records what it takes to collapse it.

The McKee formula links the two. It estimates compression strength from ECT, board thickness, and perimeter. In its common form, strength in pounds is 5.87 × ECT × √thickness × perimeter. Use ECT in pounds per inch and the other terms in inches. 

The formula was built for regular slotted cartons. Die-cut and reinforced styles can differ from it by around 25%. A floor display is neither, so the result is a screening figure. A physical test has to confirm it.

Flute thickness decides where each board goes

• E-flute, about 1.6 mm: print-heavy panels and light shelves
• B-flute, about 2.5 mm: shelves, die-cut parts, and puncture resistance
• C-flute, about 3.6 mm: uprights and bases
• BC double-wall, about 7 mm: heavy bases and tall uprights

Cut-outs also matter. Hand holes, windows, and perforations near a corner break the load path that the formula assumes. Plan graphics and windows together, and see our cardboard printed boxes for print options.

Which panels carry the load, and what has been cut out of them?

New Board and Loaded Board Behave Differently

A lab test crushes a fresh sample once. A display carries its load for weeks. A board under constant load loses stiffness slowly, a process called creep. Fibre Box Association guidance, as reported by industry engineers, suggests a loss of about 45% after 90 days under load. Long-term usable strength often sits near 50 to 60% of the lab figure.

Damp and time overlap, so the losses cannot just be added up. Planning tools apply both and warn against counting the same effect twice. 

• Long-term or sticky storage: 1.5 to 3 times
• Unconditioned or refrigerated storage: 3 to 5 times
• Time, humidity, and transport connected: 3 to 7 times

The range is wide because the inputs vary so much. So we ask for the promotion length, the store type, and the delivery route before choosing a board.

One unit stocked with jars stood for three weeks. The uprights held. The bottom shelf spanned a wide gap with no divider, and it had dished by the end of week two. The board grade was fine. The unsupported span was too long for three weeks under load.

Real Loads Arrive Unevenly

Nobody loads a shelf evenly. Product is stacked towards the front edge, restocked by hand, and pulled forward by shoppers. Trolleys clip the base. Load concentrates in a few places, which an ECT figure does not capture.

A four-point bend test checks shelf sag under distributed weight. A display also has to cope with point loads. Common point loads include:

• Product stacked at the front edge of a shelf
• Dropped restocking, which loads a shelf suddenly
• Shoppers leaning on or pulling at the top tier
• Trolley knocks at the base corners

Where will the heaviest product sit, and who restocks it?

Which Design Moves Close the Gaps?

Most of the strength in a load-bearing cardboard display comes from structure. Board grade sets the upper limit. Design decides how much of that limit the unit reaches.

Shelves: shorten the span or stiffen the board

One design guide recommends flutes running along the span on a cardboard display shelf wider than about 250 mm. That direction resists bending best. Our structural designers set flute direction on every shelf before the die is drawn. These moves help as well:

• Fold a front lip to stiffen the edge
• Add a centre divider to halve the unsupported span
• Use heavier board on the bottom shelf, where load is greatest

Uprights: keep the load path clear

Vertical flutes give an upright its stacking strength. Keep windows, finger holes, and perforations away from corners. We apply a no-cut-out rule to uprights and check it on every dieline. Interlocking slots should be cut accurately, in the same way as our custom die-cut boxes. A loose slot lets panels rack under weight.

Base and footprint: it carries everything

In most floor-standing units, the base takes the whole vertical load. A weak base warps the shelves above it. On a cardboard pallet display, internal pillars aligned with the pallet stringers give the load a straight path down. Base plates are matched to your pallet footprint at the dieline stage.

For light products in tight spaces, a cardboard counter display box or a tabletop display box may be enough. It avoids a floor unit altogether. For a heavier range, match the base to a standard footprint. Weight class also changes the risk. Lighter pallet displays, under about 150 kg, mostly fight surface sag from humidity. Units having 150 to 400 kg require vertical compression strength first.

• UK standard: 1200 x 1000 mm, used for storage and full pallet delivery
• Euro: 1200 x 800 mm, used in European logistics and export
• Half Euro: 800 x 600 mm, common in retail-ready and half pallet display distribution
• Quarter: 600 x 400 mm, used for a quarter pallet display in small promotional spots

Non-standard fixtures may need bespoke corrugated packaging built to a measured spec.

Where one panel hands the load to the next

Load moves from panel to panel at every slot, tab, and glue seam. A loose slot lets panels shift under weight. The shift shows up as a lean or a bowed shelf. Tight, accurately cut slots keep the panels working together. Glue seams need enough overlap to hold when the unit is pushed or restocked. We check joints on the loaded prototype by pushing the unit gently from the side.

How Do You Choose Board for a Floor Display?

Published capacity figures vary widely. Supplier guides quote anywhere from about 5 kg to 60 kg per shelf for cardboard units. The spread comes from board grade, height, shelf span, and how the load is placed. Read every figure as a claim to test. Ask which ECT and board thickness a quoted capacity assumes. Every quote names the tested board grade behind the capacity.

Extra board has a cost. Double-wall costs more, weighs more, and can be harder to fold by hand. For a heavy-duty cardboard display, use it on the base and uprights. Support single-wall corrugated for frames and light boards.

A unit that imports already stocked requires a stronger appearance than a flat-pack floor display. If your display will arrive full, see our notes on retail packaging boxes.

How Do You Turn Product Weight into a Strength Target?

Board grade is easier to choose once you know the load the structure must survive. The example below is illustrative and uses a four-frame unit.

• Convert to newtons by multiplying by 9.81. That gives about 392 N.
• Apply a safety factor for the conditions. At 3 times, the target is about 1,180 N.

The finished prototype should reach the target that matches its storage and promotion length. One technique guide suggests a minimum of 1,200 N for a display carrying 20 kg. That is roughly six times the product weight, which sits inside the same range.

How Should You Test a Floor Display Before Trusting the Number?

Each test checks something different, and none covers the whole display. Some retailers set their own test requirements, so ask before design starts.

• Edge crush ISO 3037: strength of the board
• Flat crush ISO 3035: stiffness of the flutes
• Box compression ISO 12048: the finished structure from the top
• Loaded prototype test in-house, overnight: shelf sag and joint movement over time
• Transit test ISTA 3E: unitised loads in distribution

Our pre-production testers follow the same five steps on every new prototype.

• Confirm the total load and the load per shelf.
• Build the prototype from the production board.
• Load it fully, with a point load at the front edge.
• Leave it overnight and measure sag at the shelf midpoint.
• Repeat after a spell in damp conditions.

If a display fails at step four or five, the fix is usually structural. A divider, a lip or a thicker bottom shelf often solves it.

Five Mistakes That Undo a Good Rating

A good board grade cannot rescue a weak design. These mistakes cause much of the trouble:

• Specifying from the ECT figure alone, with no prototype test
• Ignoring where the unit is stored before installation
• Cutting windows or hand holes into a corner panel
• Leaving a wide shelf span with no divider
• Testing with an even load only, when real product sits at the front edge

All five are cheap to fix at the design stage and expensive to fix in store.

Ready to Brief a Floor Display?

Send the product weight, unit count, and footprint, and we will work from those. Hale Path Packaging builds corrugated floor displays, counter units, and pallet displays in runs of 100 units. Finished units ship 7 to 14 working days after proof approval. We explain the custom packaging MOQ before you commit.

Questions Worth Asking

What ECT do I need for a floor display? Heavier or taller units move to double-wall. We ask for the product weight and store conditions before naming a grade.

Does a higher ECT always mean a stronger display? No. A higher ECT rating helps the uprights. It does nothing for a long shelf span, a loose joint, or a cut-out in the wrong place.

How much weight can a cardboard floor display hold? It depends on the design. Published figures range from about 5 kg to 60 kg per shelf. We test a loaded prototype before we quote a capacity.

Does damp storage matter if the shop is heated? Yes. The board often sits in stockrooms and delivery vehicles that are damper than the shop floor. It also carries its load for weeks, which lowers cardboard display strength further.

Can a display ship already stocked? Yes, if it is built for it. A stocked floor display needs stronger uprights and a stronger base than a flat-packed one. We size the uprights and base for the delivery method you choose.

Can a cardboard floor display be reclaimed in the UK? Corrugated cardboard is widely reclaimed in the UK. A recyclable cardboard display keeps to one material where possible. Plastic windows, foil and heavy laminate should come off first. Our green boxes range shows how we keep coatings light.

Conclusion

An ECT rating is a sound starting point for choosing board. The number describes a dry strip of board crushed once. A floor display in the UK faces damp air, weeks under load, and uneven weight.

Four gaps separate the lab from the shop floor. They are humidity, the jump from strip to structure, time under load, and uneven loading. Design closes each one. Shorter shelf spans, clear load paths, a strong base, and accurate joints do more than a higher rating on its own.

• ECT measures the strength of the board in kN/m. The finished display needs its own test.
• UK humidity can cut board strength by about 20% to more than 50%.
• Time under load lowers strength further, so a safety factor is needed.
• Shelf span, load path, base, and joints decide much of the result.
• A loaded prototype is the final check.

Start with a sensible board, then build a prototype and load it. Testing a loaded prototype catches many failures before the display reaches a store.

Hale Path Packaging builds corrugated floor displays around your product weight and store conditions, and loads a prototype before print. Send us your brief, and we will start from there.