Rack-clad cold stores
The racking is the building structure and the insulated envelope hangs on it, which is efficient for tall automated freezers and fixes the layout for good.
Last updated 2026-09-06
What is Rack-clad cold stores?
In a rack-clad cold store the racking is the building. Instead of erecting a steel frame and then installing racking inside it, the rack structure itself carries the roof and the cladding, and the insulated envelope is hung on the outside of the racking. There is no separate frame. That removes a whole layer of structure and the clearances that go with it, which is why rack-clad construction dominates very tall automated stores. Heights that would be awkward in a conventional shed become straightforward, and the volume enclosed per unit of structure is far better than a framed building can achieve.
The efficiency comes with a permanent commitment. Because the racking is structural, it cannot be moved, extended or reconfigured. The aisle layout, the bay dimensions, the pallet positions and the crane runs are fixed at design stage and remain fixed for the life of the building. An operator who later wants wider aisles, different pallet sizes or a different handling system is looking at a new building, not a reconfiguration. The design also has to be right in a way that a framed building forgives, because the racking is simultaneously the storage system, the structure carrying the cladding and the wind load, and the guide system for automated cranes, and the alignment tolerances of an automated crane runway are far tighter than ordinary structural steel tolerances.
The other consequences are fire strategy and maintenance. A tall, dense, automated frozen store with a structural racking system is a difficult fire engineering problem, and the strategy is developed by specialists early because it affects the structure, the envelope and the handling system rather than being applied afterwards. Maintenance is also harder. Access into a tall automated frozen store is restricted, the environment is cold, and much of the envelope can only be reached from outside. On most projects the sequence is that the racking is erected and surveyed first, then the envelope is hung on it, which means the building is weathertight late and the erection of the racking happens in the open. The refrigeration plant is designed, installed and commissioned by the refrigeration specialist under its own regime, and the staged pull-down of a very tall frozen box is a long and carefully managed operation.
How does Rack-clad cold stores work, step by step?
- 1
Step 1: Fix the handling system and the layout permanently
Everything follows from the automation. Pallet dimensions, load weights, crane type, aisle count, bay sizes and building height are settled before the structure is designed, because they are the structure. The designer, the racking specialist and the automation supplier work together to lock the geometry, and the client accepts that the layout is permanent. On most projects this is the single most important commercial decision on the project, and the time spent on it before design starts is repaid many times over.
- 2
Step 2: Design the racking as a building structure
The rack structure carries the roof, the cladding, wind and snow loads and the loads of the stored product and the cranes, all at once, and it does so at a height where stability and deflection govern. It is designed as a structure, with foundations, bracing and connections engineered accordingly. The foundation design has to suit a heavily loaded, closely spaced grid of uprights rather than a small number of frame bases, and settlement tolerances are tight because crane alignment depends on them. The construction team coordinates the foundations, the floor and the rack setting out as a single problem.
- 3
Step 3: Build the floor and the heave protection first
The floor is built before the racking and cannot be revisited. Where the store runs below freezing, the heave protection specified by the designer is installed within the build-up, tested, photographed and recorded before covering, and monitoring points are provided. Slab flatness and level are set by the crane runway rather than by ordinary industrial floor criteria, and they are surveyed and accepted before erection starts. A floor that is out of tolerance under a rack-clad store is not a snag, it is a structural and operational problem with no easy remedy.
- 4
Step 4: Erect and survey the racking to structural and crane tolerances
The racking is erected in the open, working upwards, with the alignment surveyed continuously rather than checked at the end. Two sets of tolerances apply at once: those of a building structure and the far tighter ones of an automated crane runway. Erection is a large working at height operation with its own lifting and access arrangements, and the stability of the partly erected structure is designed and managed as a temporary works problem. The survey record produced at this stage is one of the key handover documents.
- 5
Step 5: Hang the insulated envelope on the rack structure
Wall and roof panels are fixed to the racking through a support system designed to carry them and to accommodate movement. The envelope is hung from a structure that deflects under load and moves with temperature, so the fixings and joints are designed for that movement rather than treated as if fixed to a stable frame. The vapour barrier is installed and sealed continuously on the warm side, which is harder here than in a framed building because the supporting structure penetrates the envelope line frequently. Every one of those penetrations is a designed detail with a thermal break.
- 6
Step 6: Resolve the fire strategy through the whole design
A tall, dense, automated store is a specialist fire engineering problem, and the strategy is developed early with the designer, the insurer and the relevant authorities. It affects the structure, the envelope, the detection and suppression arrangements, the access provisions and the automation. Suppression pipework and detection within a frozen rack-clad store also have to be arranged so they cannot freeze and so they can be maintained in a space designed for cranes rather than people. None of this can be added late without disturbing the structure it hangs on.
- 7
Step 7: Plan access and maintenance into a building that has none by default
A rack-clad store has no walkways, no spare aisles and no easy access to the envelope from inside. Maintenance access to the cranes, the coolers, the detection and the envelope is designed in from the start, including how equipment is recovered from height in a cold room and how anyone working inside is protected and monitored. Much of the external envelope is reachable only by mobile access equipment from outside, which has implications for the yard layout and for the long term maintenance budget.
- 8
Step 8: Commission the structure, the automation and the cold together
Commissioning has three strands and they interact. The automation is proved against the surveyed rack alignment, the refrigeration specialist commissions the plant under its own regime, and the box is pulled down in long, controlled stages so that a very tall structure contracts gradually and predictably. Rack alignment is re-surveyed cold, because the structure moves as it comes down to temperature and the crane has to work in the cold building rather than the warm one. Thermal imaging of the envelope while cold finds the bridges around the many structural penetrations, and it is done before the store is loaded.
What are the benefits of Rack-clad cold stores?
- Removes a whole layer of building structure, so the enclosed volume per unit of steel is far better
- Makes very tall stores practical, which is where automated handling earns its return
- A smaller footprint for the same storage volume, which matters on constrained sites
- Less envelope area per pallet stored, which reduces heat gain and running cost
- Suits automated cranes because the racking and the guidance system are one structure
- Erection of racking and envelope can be sequenced as a single specialist operation
What are the limitations of Rack-clad cold stores?
- The layout is permanent, and the racking cannot be moved, extended or reconfigured
- Design errors in geometry or handling cannot be corrected later without a new building
- Fire strategy is a specialist problem that shapes the structure, envelope and automation from the outset
- Maintenance access is inherently poor, and much of the envelope can only be reached from outside
- Alignment tolerances are far tighter than ordinary structural steel, and depend on the floor and foundations
- The racking is erected in the open, so the building is weathertight late in the programme
What is Rack-clad cold stores best suited for?
What plant does Rack-clad cold stores need?
- Heavy lifting and mobile access equipment for erecting racking at height in the open
- Precision survey equipment for continuous alignment monitoring during erection
- Laser screeding and floor survey equipment for a slab set to crane runway tolerances
- Panel handling and fixing equipment suited to hanging cladding from a rack structure
- Testing and recording equipment for the under slab systems before covering
- Data logging and thermal imaging equipment for a long staged pull-down
How is Rack-clad cold stores quality-checked?
- Floor flatness and level surveyed and accepted against crane runway criteria before erection
- Rack alignment surveyed continuously through erection and recorded as a handover document
- Temporary stability of the partly erected structure designed and inspected as temporary works
- Envelope fixings checked for the movement of the supporting structure rather than treated as fixed
- Every structural penetration of the envelope recorded, sealed and thermally broken
- Rack alignment re-surveyed cold and the envelope thermally imaged before the store is loaded