The Vertical Warehouse: How Mezzanines Improve Space Optimization

Warehouse design doesn’t just involve planning for sprawling square footage. You also need to think about vertical space intelligently. As eCommerce orders increase and new retail spaces become scarce, businesses are finding ways to expand and optimize their warehouse by growing up instead of out with mezzanines and pick towers.

A mezzanine is an elevated platform installed to expand your current warehouse pick space, but its impact goes far beyond simple expansion. When thoughtfully designed and paired with automation, a mezzanine transforms how warehouses handle labor, inventory flow, and operational scalability.

If your warehouse already has a mezzanine or pick tower, you can improve your existing facilities with flexible automation. Conversely, for new builds that want to leverage vertical space, you can combine mezzanines with automation and remain flexible, unlike with alternative high-density automation solutions.

On the “Warehouse Automation Matters” podcast, I spoke with Erik Pichette and Adam Schwarz of Locus Robotics about how mezzanines can help improve warehouse operations, and why businesses must think beyond the surface when incorporating these structures into their facilities.

Mezzanines as Space Savers

In an age where warehouse space comes at a premium, the value of thinking vertically cannot be overstated. According to Supply Chain XChange, the uncertainty and volatility seen in 2023 and 2024 caused a “slowdown” in decision-making for things like expansion plans. Expanding horizontally isn’t always feasible, but mezzanines allow warehouses to build upward and make the most of their existing footprints.

Pichette explained the appeal of using vertical space in a warehouse: “Instead of going east to west in your existing space, you really want to leverage that north-to-south space to ensure that you’re using it as efficiently as possible.”

The Art of Mezzanine Design

While the concept of a mezzanine itself may seem straightforward, mezzanine design requires careful orchestration. Every decision, from aisle width to SKU placement, affects the efficiency of the entire operation. Pichette and Schwarz worked on a mezzanine optimization project for a major home improvement retailer, which was an effort that highlighted both the challenges and opportunities of this process.

One critical insight – that labor and inventory flow must be designed in tandem – offered a question that warehouses should answer. “How much volume are you going to be putting through per floor?” Pichette asked. “And how do you spread labor effectively to handle that volume?” These are considerations any warehouse executive needs to ask themselves, and they’re critical to ensure the success of mezzanine systems.

For example, mezzanine floors that are closest to packing stations often have the highest volume output. Yet, downstream processes, like how empty totes are replenished, can create unexpected bottlenecks. Designing for these nuances requires collaboration across all stakeholders, including automation vendors, warehouse managers, and even the frontline workforce.

Mezzanine Best Practices: From Slotting to Safety

Optimizing mezzanines involves a series of interconnected decisions, but some principles are universal. Pichette and Schwarz highlighted several key strategies:

• Strategic Slotting: High-frequency items should be placed where they’re easiest to access. “We want to ensure that high movers are in advantageous locations,” Pichette explained, “whether that’s near conveyor drop-off points or in wider aisles for better traffic flow.”
• Dynamic Layouts: Incorporating flexibility in mezzanine design can future proof the space. Wider aisles and adjustable racking systems make it easier to adapt to changing inventory profiles.
• Clarity: Simple visual cues, such as floor markings or labeled zones, make a huge difference in worker efficiency. As Schwarz noted, “Clearly defining the space with floor tape or something along the wall to illustrate storage areas is an easy but critical best practice.”

Mezzanines and Warehouse Automation

The role of automation in mezzanine operations cannot be overstated as automated systems, such as autonomous mobile robots, streamline the movement of inventory across multiple floors. Schwarz emphasized the importance of conveyor flow and robot charging areas, which must be carefully planned to prevent disruptions.

For example, some facilities are exploring compact vertical lifts or carton elevators to move goods efficiently between levels. These solutions, which take up less space than traditional conveyors, reflect the growing sophistication of mezzanine automation.

AI and Predictive Optimization

The integration of artificial intelligence (AI) and machine learning promises to elevate mezzanine operations even further. From dynamic slotting to predictive labor allocation, AI tools can make real-time decisions that improve efficiency. As Pichette envisioned, “How do we use [AI] to autonomously slot and make slotting decisions based on volatility within the week?”

Imagine a warehouse where AI predicts not only which SKUs will move the fastest but also how many workers will be needed on each floor at any given time. It’s a future that’s already taking shape, with predictive analytics and demand forecasting driving smarter decisions.

ROI and Scalability for Success

Ultimately, the success of a mezzanine system comes down to its impact on operational performance. Improved labor productivity, reduced congestion, and faster fulfillment times are just a few of the benefits that businesses can expect. But as Pichette reminded, it’s critical to involve all stakeholders early in the design process: “Once a mezzanine is developed and bolts are in the ground, it’s a pretty fixed structure. It costs a lot to make changes.”

By taking the time to design for scalability and efficiency from the outset, companies can ensure that their mezzanines continue to deliver value for years to come.

Mezzanines are much more than elevated platforms and are a strategic approach to solving space constraints while optimizing operations for peak performance. For companies looking to scale their warehouses without expanding their physical footprint, mezzanines paired with automation offer a compelling solution.

Want to learn more about the intricacies of mezzanine design? Hear Erik Pichette and Adam Schwarz dive deeper into the topic on this episode of Warehouse Automation Matters. Listen now and discover how you can rethink your warehouse space for the challenges of tomorrow.