Aisle width is one of the most influential variables in warehouse design. The space between pallet racks determines how efficiently forklifts can operate, how safely goods can be handled and how many pallet positions a building can ultimately hold.
When looking at how much space is needed between pallet racks, the correct answer is – it depends on a number of factors including the handling equipment, pallet sizes and operational requirements. There is no single universal measurement, but there are established guidelines and practical ranges across UK warehouses.
What is meant by ‘space between pallet racks’?
The phrase usually refers to working aisle width, which is the clear distance between two rows of pallet racking that allows a forklift to manoeuvre and place a pallet safely. This is different from:
- Flue space – Gap between back-to-back racks for fire safety
- Wall clearance – Gap between racking and building walls
- Frame-to-frame spacing – Structural distance between rack rows
In most layouts, when people ask how much space is required between pallet racks, they are referring to forklift aisle width.
Typical aisle widths in UK warehouses
Forklift selection is the single biggest factor influencing how much space is required between pallet racks.
Below is a general guide used across UK warehouse design:
| Forklift Type | Typical Aisle Width Required |
|---|---|
| Counterbalance Truck | 3.0 – 4.0 metres |
| Reach Truck | 2.6 – 3.2 metres |
| Articulated Truck | 2.2 – 2.8 metres |
| Very Narrow Aisle (VNA) truck | 1.6 – 2.0 metres |
These figures are indicative. The precise requirement is determined by the manufacturer’s Ast dimension – the minimum aisle width required for a 90-degree stacking manoeuvre.
For example, a reach truck handling a standard 1,200 x 1,000mm pallet may require an Ast of around 2.8 metres. Increase pallet length or load overhang and the required aisle width increases accordingly.
Even small adjustments have large consequences. Reducing aisle width by 400mm across a 40-metre-wide building can free enough space for an additional run of racking. Over multiple bays, that can equate to hundreds of extra pallet positions.
How forklift type determines required space
Forklifts do not simply drive straight in and out of racks. They approach at an angle, pivot and adjust before placing a load. This means they require enough space to:
- Turn into the racking bay
- Lift the pallet without striking adjacent beams
- Reverse safely without impacting uprights
Counterbalance trucks need the widest aisles because they turn using the full length of the vehicle. Reach trucks extend their forks forward, allowing narrower aisles. VNA trucks operate in extremely narrow aisles but typically require guide rails or wire guidance systems.
The narrower the aisle, the more precise the operation must be. In high-throughput environments, tight tolerances can increase pressure on operators. In slower storage settings, narrower aisles may be entirely practical.
The space between pallet racks must reflect not only machine capability but also real-world working conditions.
Minimum clearance between pallets and racking
Beyond aisle width, internal clearances within the racking system affect both safety and usability.
Standard practice in the UK typically allows:
- Around 75mm clearance between adjacent pallets
- Around 100mm clearance between pallet and upright
- Adequate vertical clearance between pallet top and next beam level
These tolerances account for pallet variation, shrink-wrap bulge and minor driver misalignment.
If spacing is too tight, beams are more likely to suffer impact damage. If it is too generous, capacity drops unnecessarily. The correct balance depends on pallet consistency and operator skill.
In facilities with mixed pallet quality, slightly greater clearance can reduce long-term maintenance costs.
Fire safety and flue space requirements
Fire regulations influence how much space is required between pallet racks, particularly in sprinklered buildings.
A flue space is the vertical gap between back-to-back pallet loads. It allows sprinkler water to penetrate through the racking during a fire event.
Typical guidance includes:
- A minimum 150mm longitudinal flue space between back-to-back racks
- Clear transverse flue spaces between pallets
Exact requirements depend on building design and sprinkler specification. Insurers may also impose conditions.
Fire spacing is often overlooked during capacity optimisation exercises. However, failing to maintain flue gaps can compromise system approval and insurance compliance.
Wall and building clearances
Racking is rarely installed tight against external walls. Buildings expand and contract slightly with temperature changes, and minor structural movement must be accommodated.
Allowing 100 – 300mm between racking and perimeter walls provides:
- Inspection access
- Reduced moisture contact
- Tolerance for uneven walls
- Maintenance space
Older buildings in particular may require greater allowances due to irregular construction.
These clearances may seem small individually, but across an entire warehouse they meaningfully influence layout planning.
When should you review aisle spacing?
Aisle width is not fixed forever. It may warrant reassessment when:
- Expanding into adjacent units
- Changing forklift type
- Experiencing frequent rack damage
- Increasing pallet height
- Reconfiguring stock profiles
Revisiting layout design during lease renewals or operational upgrades can unlock additional capacity without relocating premises.
However, any change must include structural checks, updated load signage and confirmation that floor load capacity remains suitable.
Conclusion
For most UK warehouses:
- Counterbalance operations typically require around 3.0 – 4.0 metres
- Reach truck layouts often operate between 2.6 – 3.2 metres
- VNA systems can function within 1.6 – 2.0 metres
Beyond working aisles, you must also allow for pallet clearance, flue space and wall tolerances.
The right measurement is the one that allows safe, controlled handling while supporting your long-term storage strategy. Capacity matters, but usability matters just as much.
If you are reviewing your current layout or planning a new installation, our team at Pallet Racking Systems can assess your available space and recommend a practical, compliant solution tailored to your operation. Get in touch to discuss your warehouse requirements and explore suitable racking configurations.