Why the footprint is the least important number
Almost every cold room enquiry starts with a floor area. It is the easiest thing to measure and the least useful thing to quote from, because the cost of a modular room is driven by panel area, panel thickness, door specification, floor construction and the distance to the condensing unit.
A taller room with the same footprint costs more, because every wall panel is taller. A room with a floor drain costs more, because the floor becomes a different construction. A room whose condensing unit has to be forty metres away on a flat roof costs considerably more, because line sizing and refrigerant charge change.
The six measurements
| # | Measurement | Why it changes the design |
|---|---|---|
| 1 | Usable internal length and width, clear of columns and pipework | Set the panel grid and the number of wall panels |
| 2 | Finished ceiling height available, floor to underside of any beam | Panel height, light fitting depth, rail clearance |
| 3 | Door position, width, and which way it must swing; trolley turning circle | Door leaf width, frame, and whether a slider is required |
| 4 | Floor level relative to the surrounding floor, and drainage available | Whether a floor drain, ramp or insulated floor is needed |
| 5 | Intended condensing unit position and pipe run, including vertical lift | Line sizing, refrigerant charge, oil return |
| 6 | Route the panels must travel from the unloading point to the site | Maximum panel length that can physically reach the room |
Number six is the one that causes the most expensive surprises. A 2.4 m panel that will not pass a stairwell or a service lift has to be reordered in shorter modules with more joints, which is more material and more labour.
Door specification: the detail that decides daily usability
Cold room doors are where the operating experience is made or lost. Three decisions cover most of it.
- Hinged or sliding. Hinged is cheaper and seals better. Sliding avoids a swing area and is usually required where a forklift or trolley needs the space in front.
- Width and height. Measure the widest thing that will ever go in — usually a pallet truck with a load — and add clearance. Doors are not the place to save 100 mm.
- Heated frame and threshold. Any room running below about 2 °C needs an anti-condensation heater in the frame and often in the threshold, or the door will freeze shut in humid weather.
Temperature class decides more than you think
- Chiller 0 to 8 °C — standard panel thickness is usually adequate
- Freezer −18 °C — thicker panels, heated door frame and threshold, insulated floor
- Blast or rapid −30 °C and below — two-stage or specially selected condensing unit
- Every step down adds cost in the panel, the door and the refrigeration, not just the last one
Drainage, floors and cleaning
A cold room floor is a decision, not a default. Three common options exist, and the right one depends on how the room is cleaned and what is stored in it.
An insulated floor panel with a factory-fitted drain is the cleanest option and the most expensive. A site-poured floor with a cast drain is cheaper but introduces a construction dependency into the schedule. No drain at all is acceptable only where the room is genuinely dry and cleaned by hand.
Whichever route is taken, the drain must be trapped and protected against freezing. A frozen drain in a freezer room turns a small cleaning problem into a room that has to be taken out of service.
Condensing unit position: the decision people make last
The condensing unit is usually positioned after the room, which is backwards. Distance and lift determine line sizes, refrigerant charge and, in some cases, whether a remote unit is viable at all.
- Keep the run as short as the building allows, and avoid unnecessary vertical lift
- Make sure the unit has access to cool air and can be serviced without a crane
- Confirm the mounting point can carry the weight and is not above a noise-sensitive area
- Agree who runs the cable and the pipe route, and in what sequence
Most cold room disputes we see are about the interface: who pours the floor, who runs the pipe, who seals the penetration. Fix that in the contract and the installation rarely goes wrong.
What to send for a firm quotation
Send the six measurements, the intended product and daily throughput, the required internal temperature, and a photograph of the space including the ceiling and the likely plant location. With those in hand a modular room can be laid out and priced without a site visit in most cases.
If the room is part of a larger fit-out with a fixed opening date, say so at the start. Panel production is short, but door hardware and condensing units are often the long-lead items, and knowing the date lets us sequence the order correctly rather than optimising each component in isolation.
Tan runs the sheet-metal area at Dixue and has been building commercial refrigeration cabinets for eighteen years.
