Insights

By Brent Willett

Engaged SCM | Warehouse Modernization

Why after-hours materials access is becoming a standard operating model issue in asset-heavy warehouses.

In a lot of asset-heavy operations, the plant never sleeps, but the warehouse does. Maintenance, operations, and reliability teams still need access to materials after hours, yet many organizations have never fully designed the control model that supports that reality. Instead, they rely on workarounds.

You’ve probably seen some version of this:

• Technicians grab what they need overnight and jot it down for someone to sort out in the morning.

• Security escorts employees into the storeroom and tries to validate requests in SAP.

• Or worse, access is technically restricted, but in practice, people just “figure it out” when production is on the line.

These aren’t different strategies. They are all symptoms of the same gap:

A 24/7 operation running on a part-time inventory control model.

The Question Most Companies Get Wrong

When this issue comes up, the first question is usually, “Do we need to staff the warehouse 24/7?” In most cases, the answer is no.

A better question is: What level of after-hours inventory access is appropriate based on operational need, material criticality, and control risk?

This is an important distinction because the reality is that not all inventory and not all access carries the same risk. Very few operations need unrestricted access to all inventory after hours. Instead, they need reliable access to the right inventory, by the right people, under the right controls.

Why This Matters More Than It Seems

When companies don’t define these zones, they default to inconsistency and that is where the cost creeps in. Studies have shown that inventory record accuracy in poorly controlled environments can drop below 65-70%, especially when after-hours activity isn’t properly captured. Duplicate or “just in case” ordering, which is often driven by a lack of trust in inventory data, can inflate inventory levels by 10-20% or more. And obsolescence and excess inventory typically account for 15-30% of total MRO inventory value in industrial environments. In other words, what looks like a small process gap after hours, often turns into a very real working capital problem.

What This Actually Requires: A Designed Access Model

Solving this isn't about adding headcount or tightening rules. It's about designing a simple, enforceable operating model that aligns access with risk and that starts with understanding that not all inventory carries the same risk profile.

The most useful way to think about segmentation is across two dimensions: how critical is this item to uptime, and what is the financial and accuracy exposure if it goes untracked? Those two questions place any material into one of four segments, each of which requires a different access and control approach.

Critical spares sit in the high-criticality, lower-control-risk quadrant. These are the items that can stop production but they're typically well-known, relatively stable in count, and manageable with structured access. The goal here is not to restrict access but to make sure every transaction is captured. Role-based access for maintenance technicians and on-call personnel, combined with SAP reservation discipline and a designated after-hours stock zone, is usually sufficient. Pre-kitted materials for planned work and scan-to-issue processes remove friction while preserving the transaction record.

Consumables are low criticality and low control risk. Missing a transaction on a box of gloves or a tube of thread sealant won't distort your inventory position meaningfully. These items should be as frictionless as possible: open shelving, floor stock, or vending machines for high-volume items. Periodic cycle counts are enough. The mistake organizations make here is applying the same controls as critical spares, which creates unnecessary friction and erodes technician trust in the whole system.

High-value or sensitive items are where the tightest controls belong and the only quadrant where technology like smart lockers or crib systems is genuinely justified rather than aspirational. These items combine operational importance with significant financial exposure if they go missing or untracked. Supervisor authorization, dual sign-off, and a full audit trail are appropriate here. This is also the quadrant most likely to trigger duplicate ordering if planners lose confidence in the system balance, so the transaction discipline is non-negotiable.

General MRO is the quadrant most organizations get wrong and where the majority of working capital leakage quietly accumulates. These items are lower criticality, meaning a missing bearing won't shut down the plant tonight, but the control risk is high. Across hundreds of SKUs and multiple shifts, untracked after-hours consumption distorts demand signals and erodes planner trust. Technicians who can't reliably find items or don't trust system balances start pulling extras "just in case", a rational response to an unreliable system, but one that inflates inventory levels and accelerates the problem. The fix is not tighter access restrictions. It's making the transaction easier to complete than to skip. Work order linkage at the point of issue, a designated staging area, and a real next-day reconciliation process, owned by someone, completed before 10am, are the foundation. Basic barcoding tied to work orders works well here when the behavioral foundation is in place to support it.

This segmentation logic is what drives the access model, the physical layout of after-hours stock areas, and the enabling technology decisions. When everything is treated the same, nothing is controlled properly.

The organizations that get this right don’t just improve inventory accuracy. They reduce working capital, improve planner trust in the system, and eliminate one of the most persistent sources of operational friction in asset-heavy environments.

The Bottom Line

This is why after-hours inventory access should be treated as an operating model design issue, not simply a warehouse staffing issue. The goal is not to fully man stores around the clock, nor is it to accept weak controls in the name of uptime. The goal is to create a risk-based after-hours inventory access model that protects uptime, inventory accuracy, and financial integrity at the same time.

For industrial organizations running 24/7 operations, this is not a niche warehouse problem. It is a repeatable challenge across asset-heavy environments, and one that deserves more attention as companies look to modernize warehousing, improve SAP discipline, and reduce operational friction.

If this is a challenge in your operation, it’s likely not a staffing issue; it is a design issue. Engaged SCM helps organizations build after-hours inventory models that protect both uptime and control.

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About the Author

Brent Willett is Founding Principal of Engaged SCM Inc., a supply chain advisory firm that helps asset-heavy industrial organizations make better operational and technology decisions, then shows up to deliver them.

Brent is a Chartered Professional Accountant with senior advisory experience at Deloitte and EY. He is the former CEO of Supply Chain Canada (Alberta Institute) and currently serves as a strategic advisor to the Alberta Logistics Centre of Excellence.

Connect with Brent on LinkedIn.

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