Accueil<\/a> \u00a0\/\u00a0 Connaissance des produits<\/a> \u00a0\/\u00a0 Cold Room Floors: Frost Heave, Insulation and Heating<\/span><\/p>\n Most cold room failures that show up years after handover do not start in the walls. They start under the slab. A cold room floor<\/strong> on a freezer running at \u221218\u00a0\u00b0C or colder pulls heat out of the ground beneath it every hour of every day. Once the subsoil drops below zero, the water in it freezes, expands and lifts the slab. That is frost heave \u2014 and by the time you see a crack at the door threshold, the fix is usually a full floor removal. This guide covers when heave is a risk, the three ways to stop it, how thick the floor insulation needs to be for each temperature band, and the build-up sequence that keeps a cold room floor flat for the life of the building.<\/p>\n Chillers are usually safe. A room held at 0 to +5\u00a0\u00b0C loses some heat through the floor, but the ground under it stays above freezing, so nothing expands. The problem begins below zero, and it gets worse fast as the temperature drops:<\/p>\n Two site conditions make it worse. A high water table<\/strong> \u2014 common along the coasts of Latin America, West Africa and the Gulf \u2014 means more water in the soil to freeze. And fine-grained soils<\/strong> (silt, clay) hold water and form ice lenses far more readily than sand or gravel. If your site has either, treat the cold room floor as a structural problem, not an insulation afterthought. Our guide to cold storage in hot climates<\/a> covers why tropical sites are not immune just because the air is warm.<\/p>\n Frost heave is not gradual settlement. It is upward pressure \u2014 often several centimetres over a few seasons \u2014 and it is rarely uniform, so the slab tilts and cracks. The visible symptoms usually arrive in this order:<\/p>\n At stage four the insulation is wet and has lost most of its R-value, the refrigeration plant is running longer to hold temperature, and the only real repair is to strip the floor and rebuild it. That is why the cold room floor is the one part of the build where getting it right first time is worth more than any later upgrade. Frost heaving<\/a> is well documented as a soil mechanics phenomenon; what is often missed is that a freezer creates permafrost conditions under a slab regardless of the climate outside.<\/p>\n All three work on the same principle: keep the ground under the slab above 0\u00a0\u00b0C so there is nothing to freeze. They differ in cost, energy use and how well they suit a given site.<\/p>\n A grid of ducts or a void is built under the base slab, open to outside air at both ends. Ambient air moves through, replacing the heat the freezer extracts. In hot climates this is the most attractive option: the outside air is already warm, so a passive system with open vents often does the job with no running cost. In cooler regions or for ultra-low rooms, small fans force the airflow. The trade-off is depth \u2014 the ducts add 200 to 300\u00a0mm to the excavation \u2014 and vents must be kept clear of debris and standing water.<\/p>\n Resistive heating cable is laid in the sand bed or cast into the base slab below the insulation, controlled by a thermostat sensing the soil temperature and set to hold around +3 to +5\u00a0\u00b0C. This is the simplest to install, works on any site regardless of ground conditions, and is the usual choice for small and medium freezers. The cost is continuous electrical draw \u2014 modest, but it never switches off for the life of the room \u2014 and the cable cannot be repaired without lifting the floor, so cable quality and a duplicate circuit are worth paying for.<\/p>\n A closed loop of pipe under the base slab circulates warm glycol, usually taking waste heat from the condenser side of the refrigeration plant. It uses heat that would otherwise be rejected to the air, so the running cost is close to zero once installed. It is the standard on large industrial freezers and cold stores where the plant is already sized to provide it. On small rooms the pumps and controls rarely justify themselves.<\/p>\n Raised floors and container cold rooms sidestep heave entirely. A container-based freezer sits on its chassis with an air gap underneath, which is one reason it suits remote and off-grid sites. Modular walk-in rooms built on an existing warm slab (inside a warehouse, for example) also avoid the problem, because the host building keeps the ground above zero. This is one of the practical differences we cover in chambre froide en kit vs chambre froide sur mesure<\/a>.<\/p>\n Heave protection keeps the ground warm. Insulation keeps the freezer cold without burning power to do it. The two are separate layers and both are needed. Floor insulation is almost always extruded polystyrene (XPS) or PIR board rather than the sandwich panels used on walls, because the floor has to carry racking and forklift loads \u2014 look for a compressive strength of at least 300\u00a0kPa for wheeled traffic. Thickness follows the same logic as wall panels, adjusted upward because the floor sees the ground rather than the air:<\/p>\nCold Room Floors: Frost Heave, Insulation and Heating for Freezer Rooms<\/h1>\n
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When a cold room floor is at risk of frost heave<\/h2>\n
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What frost heave actually does to a building<\/h2>\n
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Three ways to protect a cold room floor<\/h2>\n
1. Ventilated sub-floor (passive or forced)<\/h3>\n
2. Electric heating cables or mats<\/h3>\n
3. Glycol heating loop<\/h3>\n
The fourth option: get the floor off the ground<\/h3>\n
Floor insulation: thickness by temperature band<\/h2>\n
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