Cold storage is the least forgiving building type we work on. A warehouse that leaks air is an inconvenience. A freezer that leaks air is a frost heave problem that will lift your slab.
Reclaimed ground, superflat slabs
The site was reclaimed coastal fill — exactly the ground condition you do not want under a slab that must stay flat to FM2 tolerance while carrying 48,000 pallet positions on narrow-aisle racking.
We treated the ground with vibro stone columns, then monitored settlement for 90 days before releasing the slab design. That pause was the single most argued-about item in the programme. It was also the reason the slab survey came back inside tolerance on all 28 panels.
The vapour strategy comes first
In a −25 °C room, the vapour barrier is the building. Get it wrong and you get ice forming inside the insulation, which then stops being insulation.
We signed off a full vapour strategy — barrier continuity, penetration details, sealing sequence — before any panel was fixed. Every service penetration through the cold envelope was detailed individually and inspected as a hold point, not a snag item.
Under-slab heating, because physics
Beneath the freezer we installed a glycol under-slab heating loop. It sounds absurd — heating the floor of a freezer — but without it the ground below freezes, expands, and heaves the slab you spent six months getting flat.
Twenty-one days of pull-down
Cooling a building this size to −25 °C is done slowly, on a curve, with structural movement monitored throughout. Rush it and you thermally shock the concrete.
We pulled down over 21 days with survey points read daily. Movement stayed inside predicted tolerance. The client loaded first pallets nine days after handover.