Building vertically: Addressing key considerations of multi-storey warehouses
Since the pandemic changed the face of retail, surging our demand for online shopping, the logistics industry has struggled to keep up to deliver more efficient space. Occupiers are facing ongoing capacity pressures, tighter regulations and expectations around sustainability. Ìý
To overcome these increasing pressures and support the delivery of Last Mile logistics, the UK must take initiative from its Asian counterparts as multi-storey warehousing comes to the fore. Could these high-rise developments be the answer?Ìý
Developing multi-storey warehouses requires careful consideration as the complexities rise with each level, with many design challenges to overcome. Here, our technical specialists explore some key considerations to ensure their successful delivery.
01 November 2023 | 4 min read
Kester Purslow John Clayton Barry McAllister
What are multi-storey warehouses?
Multi-storey warehouses are facilities built vertically with various floors that offer independent and/or interconnected areas for the storage and distribution of goods. They optimise space in strategic locations, leveraging the limited availability of suitable land in the logistics landscape.
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Different types of multi-storey warehouses
Multi-storey logistics buildings can take many forms but broadly fit into one of four main types:
Dual levels of accessible floor space with yard access at only the ground floor level. Goods lift/ mechanical handling equipment (MHE) service the upper level.
Dual floors with ramped vehicular access to the upper level to allow servicing of all units from their dedicated yard area.
Multiple levels of floor space with ramped vehicular access to the upper level, allowing all units to be serviced from their dedicated yard area.
Multiple floors with units on upper levels serviced by goods lift/MHE, with yard access at only the ground floor level.
Pros of multi-storey warehouses
- Vertical space utilisation promotes the efficient use of limited land resources, a critical factor in urban planning. Multiple floors deliver greater storage capacity whilst occupying less land space.
- Goods are organised and stored effectively on different floors to support logistics operations. When combined with advanced technology to enhance accessibility between floors, this enables efficient inventory management and movement of goods.
- Less land is required, which delivers significant cost savings and long-term cost efficiencies. Operational costs for storage, handling and maintenance can also be reduced.
- Transportation costs are lower as the warehouses are located near prime market centres to meet customer demands and strict delivery times. They improve the distribution network and are ideal for last-mile delivery, supporting fast turnover.
- Reducing the number of single-level facilities and minimising land consumption contributes to a smaller environmental footprint.
- The urban setting provides proximity to a larger workforce that can access the facility by public transport and has the potential to be part of mixed-use developments.
Addressing architectural and engineering challenges
Building multi-storey warehouses requires meticulous planning, design, and construction processes. Due to the complexity and urban location of such projects, planning, design and construction programmes are challenging and require in-depth coordination across the project timeline.
Understanding how each floor of the building is to be used, addressing the challenges of multi occupancy and how floor levels are to be accessed either by ramps and /or goods lifts are key design decisions.
Early collaboration with the project team, including planners, architects, engineers, and contractors, can provide invaluable support to streamline the planning approval, design, and construction process. This can also minimise delays and ensure efficient utilisation of resources, which is critical to delivering a measured approach.Ìý
Warehouses in urban settings must respond to their immediate surroundings in ways buildings in industrial parks do not. Landscape features are critical to integrating and harmonising multi-storey warehouses with the urban realm, façade, and elevation treatment. This helps to address the scale and nature of neighbouring buildings and the proximity and interface of pedestrians and other street users. Together with aesthetic and contextual considerations, several other design aspects set urban logistic facilities apart from their out-of-town counterparts when considering elevational treatment.
Acoustically, the façade needs to address the escape of operational noise, particularly in mixed-use areas where there may be residential neighbours and the ingress of street noise may be a factor in the design of office elements. The proximity to heavy traffic within the urban setting can also impact ventilation strategies, with fewer opportunities for window openings in office spaces.
Façades offer the potential to contribute to greening the city, and compact sites may offer the only plane on which to provide planting and habitats for increased biodiversity. The large, uninterrupted façades associated with logistic facilities offer a sustained backdrop for such provision. Although, careful selection is required concerning fire and maintenance considerations when incorporating green features. With building façades forming the sole barrier between the building’s contents and the external public realm, appropriate material selection and specification is necessary to ensure robustness and that required security levels are met, particularly at street levels.
The proximity of neighbours in the urban setting means that boundary conditions will likely require façades to be fire-rated. The height of buildings with multi-level occupancies requires more stringent fire performance characteristics for chosen cladding materials to meet regulations. As occupancies will likely be ‘stacked’, cavity barriers and separation between levels within the façade build-up will also be critical.
Multi-storey logistics buildings require distinct structural arrangements to resist significant horizontal and vertical loads, from storing palletised goods to racking systems and moving vehicles such as pallet trucks and forklifts. The selection of a column grid is a balance between achieving a column-free area, which is highly desirable, against significant structure depths to achieve long clear spans.Ìý
The upper floors may also need to consider the support of material-handling equipment (MHE) systems (e.g. robotics) that demand a high level of surface regularity and require a stiff supporting structure to limit in-service deflections. Careful consideration at both the design and construction stages is therefore necessary.
The advantages and disadvantages of steel, concrete, and hybrid frames and floors should be evaluated early in the design process, including fire resistance requirements, robustness/disproportionate collapse and accidental load scenarios.
Considering procurement, delivery times, and buildability in conjunction with whole-life cost and whole-life carbon assessments over a 60-year reference study period is critical.
Vehicles ideally require direct access to loading docks and/or vertical transportation systems to facilitate the seamless movement of goods to/from and within the logistics facility.
Ramped vehicular access, either straight or spiral, can provide direct access to all floor levels. Multiple docks on each floor allow fast and efficient loading, resulting in a high-efficiency rate and throughput capacity.
The adoption of spiral or straight ramps should consider the vehicle type(s) they will serve, for example, courier vans and heavy and/or light goods vehicles (HGV/LGV). Ramp requirements (typical gradients of 1:15) can also influence the floor-to-floor heights between levels. Ramps are very costly and require significant land to allow for manoeuvrability, particularly for heavy goods vehicles, so they require effective space planning and efficient use of land.
Upper floors can be accessed via goods lifts in these warehouses. It’s important to consider the challenges of multi-occupancy warehouses, where the lifts are shared between units and may require regular maintenance. Upper levels can, therefore, be less desired than ground-floor space due to the inconvenience of loading and unloading goods by lifts. Lift access may not be the most efficient or preferred operational outcome for occupiers and may present potential security risks, particularly in multi-tenant facilities.
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Built on constricted sites in urban settings, multi-level and multi-tenanted storage facilities increase fire safety risks. Robust fire safety is therefore critical to addressing these risks and the unique challenges presented, which include:Ìý
- Extended travel distances
- Increased fire compartment area and volume
- Implications for the external wall construction due to their scale and proximity to adjacent site boundariesÌý
- Increased firefighting risks
- Multiple tenants operating across multiple floor levels
- Complex automated storage and retrieval systems and sortation equipment and their impact on means of escape
- High fire loads
Continuous engagement is crucial throughout the project lifecycle, from the very early concept design proposals to completing the detailed design phase of the works. It’s important to critique the design as it develops to understand fire safety issues at each design stage and ensure design coordination across all disciplines.
Understanding the risks and how to mitigate them is critical to developing and implementing an appropriate fire strategy. This involves providing a safe means of escape for building occupants by addressing extensions in travel distance while providing identifiable escape routes. It’s also vital to consider the risks of materials introduced in the building design, such as green living walls and green roofs, whilst adopting materials that resist fire spread. Achieving appropriate levels of structural fire resistance and active and passive fire protection measures in buildings can help safeguard building users, rescue services and the wider community.
Ultimately, the fire strategy defines the approach to addressing fire safety and establishing the fire safety design parameters for a building. It addresses statutory obligations but also serves as a record of the concepts that underpin fire safety within a building, which can assist when preparing fire risk assessments and planning for future building works.
Implementing sustainable practices
Utilising design solutions to develop sustainable multi-storey warehouses is critical to reducing the carbon footprint generated by logistics operations. Consider:
- Taking advantage of natural lighting in working areas where possible to help maximise energy efficiency, for example, skylights, roof lights and glazing to walls. Office departments should also be limited to 8 metres in depth to reduce the need for artificial lights.
- Using renewable energy solutions such as solar panels, photovoltaics (PVs), and rainwater harvesting systems can help reduce energy consumption and reliance on external resources.
- Providing dedicated areas for recycling, reusing and waste reduction to help minimise environmental impact and manage waste.
- Employing greening measures where practical, for example, site boundaries, cycle parking shelter roofs, and elevational elements. Bird boxes, wildflower planting, insect habitats and climbing plants can also encourage ecological durability.
- Incorporating green roofs and green walls to transform the building façade aesthetically and promote biodiversity net gain. They help provide insulation, shading, and cooling effects while mitigating the visual and environmental impact of logistics buildings, as well as reducing energy consumption.
- Employing robust material selection for industrial use, conforming to BRE Green Guide A or AT.
- Using sustainable drainage system (SUDS) measures for water management, such as permeable paving/porous surfaces where possible.
- Providing transport and pollution enhanced electric vehicle hook-up. Removing on-street parking to encourage free flowing traffic and betterment of the cycling environment.
- Incorporating seating/rest areas for building users and the public to support health and wellbeing while encouraging the betterment of the streetscape environment through tree planting and landscaping features.
- Employing management measures to ensure the facility operates as intended.
Prioritising low embodied carbon solutions
Monitoring carbon as projects evolve and move through the concept, detailed design, construction, and post-construction stages is crucial. Measuring embodied carbon through a rigorous assessment can help you make appropriate design decisions to minimise embodied carbon from the outset. Undertaking a module-based Whole Life Carbon Assessment (WLCA) over a 60-year reference study period (RSP) is now a critical part of this process. The choice of low-carbon materials should be encouraged with consideration to their reuse, design life and any ongoing maintenance and/or replacement requirements.
One route to zero carbon is through the reuse and life extension of existing buildings and/or their parts. Repurposing existing buildings may prove challenging for multi-storey logistics facilities, which have relatively bespoke and often quite onerous floor loading requirements and floor-to-floor heights.Ìý
For new build projects, the choice of structural framing, envelope systems, clear spans, clear heights and, particularly, floor loads can significantly impact the carbon footprint of a multi-storey logistics building. Specifying high ‘blanket’ floor loads can be tempting for flexibility and futureproofing. This should be challenged, and floor use requirements and clear heights should be interrogated based on their intended use.
The future of logistics
Multi-storey warehouses present a forward-thinking approach to warehouse management, streamlining logistics operations. Combining innovative design, advanced technologies and sustainability considerations, these warehouses can shape the future of logistics by targeting limited land availability and increasing urbanisation. We can deliver the future of logistics.
We designed two ultra-urban logistics hubs, Project Sweetcorn and Project Sprout, bringing innovative solutions to overcome sector challenges, as featured in Property Week.Ìý
solves challenges of land prices increasing while demand for distribution, industrial and logistics space close to population hubs rises.Ìý
The design delivers a fully sustainable building that is functional yet elegant and attractive. It comprises:
- High-tech graphene façade/solar array for energy generation and water collection
- Movable/flexible racking system to allow for multiple tenants with different needs, including temperature-controlled
- Some onsite manufacturing, such as 3D printing
- Airships in with large deliveries, drones out to local last mile
- HGV loading/distribution below ground, including tube/rail link
- Some residential at a high level, leisure mid-level and retail on the ground floor facing outdoor spaces
tackles the decline of traditional high streets, the rapid rise of ecommerce and a dense urban street scene.
The design fosters community and a work/life balance in a mixed-use environment by delivering:
- Street-facing residential, workplaces, leisure and retail
- Rear-facing distribution, logistics and storage
- HGV’s / Drones from CDC in at the top, click and collect / street drones on the footpaths out
- Below-ground car parking for residents as well as tube link
- Rainwater harvesting and a vertical garden for growing salads etc. for local delivery
Key contacts
![Purslow_Kester_20181217.jpg](/imported-media/1813/purslow_kester_20181217.jpg?width=830&height=533&quality=90)
Kester Purslow
Senior Director – Architecture
![McCallister_Barry.jpg](/imported-media/2441/mccallister_barry.jpg?width=830&height=533&quality=90)
Barry McAllister
Technical Director - Structural and Fire Engineering