Pallet Building – Unit Load Creation

This topic is part of the SG Systems Global regulatory & operations glossary.

Updated October 2025 • Warehouse Execution, Packing & Shipping • WMS, Logistics, QA, Supply Chain

Pallet Building (also called unit load creation) is the controlled aggregation of cases, totes, or loose packs into a stable, labeled logistics unit that can move, store, and ship as one. In a compliant operation, pallet building is not a “stack and wrap” art—it’s a rule‑driven process enforced by the Warehouse Management System (WMS) with identity, status, and traceability captured at every scan. Done right, each pallet becomes a single source of truth: correct items and lots (GTIN, Lot, expiry), proper FEFO/FIFO rotation, safe stack pattern, verified labels (GS1‑128) and a globally unique SSCC anchor for shipping and recall.

“If the WMS can’t prove what’s on the pallet and stop what shouldn’t be, the shrink wrap is cosmetic—not control.”

1) Scope—What “Unit Load Creation” Covers (and Doesn’t)

Covers: translating pick output into stable, compliant pallets: case patterns and height rules, weight distribution, tare and gross weight capture (load cells, catch‑weighing), label printing & verification, SSCC assignment, status enforcement (Hold/Release), segregation (allergen, hazard, temperature), and final reconciliation to shipment documents and events (EPCIS, EDI).

Does not cover: improvisational stacking or ungoverned “ship what fits” habits. Pallet building is executed in the WMS using directed tasks and hard gating—not tribal knowledge.

2) Master Data—The Foundation for Safe, Efficient Pallets

Reliable unit loads start with governed masters in Document Control and the WMS: item/case dimensions and weight, orientation allowances, crush/top‑load limits, stack height, mixed‑SKU compatibility, temperature class, and allergen flags. Integrate carton rules from Cartonization so case counts and dimensions are right before they touch a pallet. Model pallet types and footprints, deck board constraints, and forklift entry—a small master error here cascades into damage and claims.

Identity must travel with the case: GTIN, lot (AI(10)), expiry (shelf life), and quantity (GS1 AIs). For serialized operations, define unit/case/pallet aggregation in Serialization – Unit/Case/Pallet with SSCC as the pallet parent.

3) Strategies—Single‑SKU, Mixed‑SKU, Route & Stop‑Build

Choose a pallet strategy based on demand and transport: single‑SKU palettes for simplicity and speed; mixed‑SKU or “rainbow” pallets for store‑friendly delivery; route or stop‑sequence builds to reduce handling at the last mile. Feed the plan from Wave Picking, Zone Picking, or discrete Order Picking, and execute with Directed Picking tasks that guide the operator to pallet build locations in the right sequence.

In high‑mix environments, use Dynamic Lot Allocation with FEFO/FIFO to substitute equivalent lots without breaking expiry rules or customer allocations. The WMS should block any pick that violates the chosen rotation policy.

4) Physical Rules—Patterns, Height, Weight & Stability

Pallet integrity depends on a few non‑negotiables:

• Patterning. Interlock patterns reduce column failure, but respect orientation limits defined in the item master.
• Height & top load. Don’t exceed case or pallet stack limits; maintain safe center‑of‑gravity and no overhang to protect edges.
• Weight. Use calibrated devices (gravimetric control, load cells), correct for tare, and understand tolerances (TNE) if weights appear on trade documents.
• Containment. Wrap/strap standards belong in SOPs; use corner boards for fragile loads and label “no top load” where applicable.

Model these as WMS rules instead of tribal tips—operators should be prevented from closing a non‑conforming pallet via hard pass/fail gating.

5) Status & Segregation—Make Mixing Physically Impossible

Never mix Quarantine/Hold with Released product. The WMS must block scans that attempt to add wrong‑status cases, wrong market packs, or conflicting allergens (Allergen Segregation). Temperature classes and hazard states should also be enforced by rule, not posters. When QA flips disposition (Component Release, Lot Release), the change must propagate instantly to picking and pallet tasks.

6) Identity & Labeling—From Case Symbols to Pallet SSCC

Each case should carry a scannable GS1‑128 label with the right AIs (e.g., (01) GTIN, (10) Lot, (17) Expiry, (37) Count). At pallet close, the system generates and assigns a unique SSCC and prints a pallet label. Apply Label Verification (online grading or scan‑back) before the pallet leaves the build zone. If label verification fails or the SSCC doesn’t reconcile to pallet contents, the WMS must refuse ship confirmation.

For multi‑market or regulated packs, lock content under Labeling Control so pallet labels (and any country statements like COO/COI) pull approved, versioned data.

7) Execution Flow—Directed Tasks, Scan Discipline

A standard build flow looks like this:

1. Start task. WMS creates a build task from wave or order release.
2. Stage base. Operator scans empty pallet ID; system assigns a provisional SSCC and validates pallet type for the SKU mix.
3. Add cases. For each case, scan validates item, lot, expiry, and rotation policy (FEFO/FIFO). Wrong scans hard‑fail; exceptions raise NCR with reason codes.
4. Weigh & wrap. Capture gross weight (with device in valid calibration status), apply containment per SOP.
5. Close pallet. WMS prints SSCC label, performs final reconciliation against pick list, and records aggregation for EPCIS.
6. Stage to door. The unit load moves to outbound staging via Directed Put‑Away to a door/route zone.

Every step is timestamped with user/device IDs under audit trail controls for data integrity.

8) Traceability & Events—Aggregation You Can Trust

End‑to‑end genealogy requires closed aggregation: case→pallet membership must be explicit and locked at pallet close. Publish events (PACK/AGGREGATE/SHIP) via EPCIS, anchor EDI 856 to the SSCC, and ensure downstream scans re‑confirm identity on receipt. During recall readiness drills, you should retrieve all SSCCs containing a lot—and the customers who received them—within minutes.

For serialized healthcare, align pallet building with Serialization hierarchies so packing doesn’t silently break parent/child relationships.

9) Dock Loading & Handover—From Staging to Carrier

Use Dock Loading & Outbound Staging to allocate pallets to doors and trailers. At handover, the WMS produces the shipping manifest and BOL, and transmits EDI (e.g., ASN) tied to each SSCC. Any door‑scan mismatch or missing SSCC blocks departure until resolved.

Track performance via OTIF and order‑to‑ship lead time.

10) Cold Chain & Condition Control

Temperature‑sensitive loads require explicit zoning, environmental monitoring, and validated storage (temperature mapping). For healthcare and food distribution, align practices to GDP and HACCP. Pallet builds should respect dwell‑time limits and seal integrity checks documented in the WMS task flow and the SOP.

11) Safety & Ergonomics

Safe palletizing is part of operational control. Reference Job Hazard Analysis (JHA) for the build station, enforce PPE, and maintain clear line clearance. If the WMS detects an overweight pallet, block movement until safe handling is confirmed.

12) Data Integrity & Validation

Pallet building relies on electronic records that must be trustworthy. Operate under Part 11/Annex 11 expectations with risk‑based CSV (GAMP 5). Qualify scales/print/scan equipment with IQ/OQ/PQ, synchronize time sources, and retain records per retention/archival policies. Ban “shadow spreadsheets”; pallet builds must exist as attributable WMS transactions with audit trails.

13) KPIs that Prove Control

• Pallet Build Accuracy (SSCC contents vs. pick list) and scan reconciliation rate.
• FEFO/FIFO Conformance and mixed‑status prevention events.
• Label Verification Pass Rate for case and pallet labels.
• Damage & Overhang Incidents by lane/shift.
• Throughput (pallets/hour) and order‑to‑ship lead time.
• Recall Readiness: time to list all SSCCs containing a lot and all customers affected.
• Overall OTIF and KPI trend stability.

Measure what prevents defects (blocked scans, label failures caught) as much as what ships.

14) Failure Patterns (and Antidotes)

• “Free build” without scans. Creates identity holes. Antidote: enforce scan‑to‑add and hard gates on pallet close.
• Mixed status on the same pallet. Quarantine sneaks in. Antidote: block wrong status; require QA disposition check on add‑scan.
• Label drift/misprints. Pallet leaves with bad SSCC. Antidote: Labeling Control + online verification.
• Pattern/height violations. Damage claims. Antidote: WMS rules for stack limits; block close if violated.
• Shadow spreadsheets for manifests. Mismatched counts at the dock. Antidote: generate manifest/BOL from WMS truth only.
• Traceability gaps for serialized goods. Lost parent/child links. Antidote: close aggregation before staging; publish EPCIS events.

15) Implementation Playbook

• Clean masters. Items, cases, pallet types, rotation rules under Document Control.
• Wire the gates. Enforce scan‑to‑add, status checks, FEFO/FIFO, label verification; block pallet close on failure.
• Align labels. Govern case/pallet templates, enable verification, and ensure SSCC prints from the WMS sequence.
• Integrate upstream/downstream. Pull picks from wave/zone tasks; push SSCCs to EDI/EPCIS.
• Validate systems & devices. Risk‑based CSV; device IQ/OQ/PQ; negative‑path tests (wrong lot, expired, failed label).
• Trend & improve. Track KPIs; drive CAPA on damage, mismatch, and label failure trends.

Don’t start with dashboards—start with gates. Dashboards describe; blocked scans prevent.

16) How This Fits with V5 by SG Systems Global

V5 WMS. The V5 WMS creates directed pallet‑build tasks, enforces FEFO/FIFO and status checks on add‑scan, assigns/prints SSCC, performs Label Verification, and blocks pallet close if counts or labels don’t reconcile.

V5 Label & Identity. Pallet and case labels are governed under Labeling Control with GTIN/GS1 AIs pulled from masters. Aggregation events publish via EPCIS and feed EDI ASNs automatically.

V5 Analytics. Real‑time KPIs track build accuracy, label pass rate, damage incidents, and order‑to‑ship lead time. Drill‑downs show where mismatches originate (zone, shift, SKU) and trigger CAPA.

Bottom line: V5 turns pallet building into a governed, auditable process where the SSCC, labels, and contents always match—and shipping documents are generated from execution truth.

17) FAQ

Q1. Can we build pallets first and assign SSCC later?
You shouldn’t. Assign a provisional SSCC at start so every add‑scan ties to the parent. Close and print the final label only after reconciliation and verification.

Q2. How do we handle partial pallets?
Use WMS rules for partials: cap height, mark as “incomplete,” and prevent loading unless the order/carrier instructions allow. The SSCC still anchors content and must appear on the manifest/ASN.

Q3. What about mixed‑SKU customer pallets?
Use zone/wave strategies with build sequences and interlocks for status and allergens. The pallet SSCC remains the parent key for events and documents.

Q4. How does pallet building support recalls?
Closed aggregation (case→SSCC), EPCIS events, and WMS audit trails let you list all SSCCs containing a lot and who received them within minutes—core to recall readiness.

Q5. What’s the minimum viable control for pallet labels?
Controlled templates under Labeling Control, SSCC generation by the WMS (not manual), and on‑line Label Verification with hard‑fail on grade/mismatch.

Related Reading
• Execution Core: WMS | Directed Picking | Wave Picking | Zone Picking
• Identity & Labels: GS1‑128 Case Label | SSCC | GS1 GTIN | GS1 AIs | Label Verification | Labeling Control
• Packing & Shipping: Cartonization | Pack & Ship | Dock Loading & Staging | Shipping Manifest | BOL
• Quality & Governance: Hold/Release | Allergen Segregation | GDP | HACCP | Audit Trail | CSV
• Performance: OTIF | Order‑to‑Ship Lead Time | KPI