Insulation decides how much heat leaks into your cold room every hour of the day, which sets how long the compressor runs, how steady the temperature stays and how much electricity you use. A typical cold room insulation thickness is 80 to 100 mm for chilled rooms and 120 to 150 mm for freezer rooms, with the upper end preferred in Saudi heat. Thickness is half the story: sealed joints, a dry foam core and an insulated floor matter as much.
How heat gets into a cold room
Heat always moves from warm to cold, so it pushes into your room through every surface around the clock. Door openings come and go, but the leak through walls, ceiling and floor never stops. Three things set its size:
- Temperature difference. A freezer at -18 °C on a 45 °C Riyadh afternoon faces a difference of 63 °C. A chiller at +2 °C faces 43 °C.
- Surface area. Every square metre counts, ceiling included.
- Insulation. Polyurethane foam conducts little heat, about 0.022 to 0.024 W/m.K. Double the thickness and the heat passing through roughly halves.
One square metre of 100 mm panel passes about 10 watts with the room at +2 °C and the outside air at 45 °C. On a -18 °C freezer the same panel passes about 14 watts. At 150 mm that drops back to about 10 watts. Multiply by every square metre of the room for 24 hours a day.
Cold room insulation thickness by temperature
| Room type | Typical room temperature | Typical insulation thickness |
|---|---|---|
| Chilled room | 0 to +4 °C | 80 to 100 mm |
| Freezer room | -18 °C or colder | 120 to 150 mm |
| Blast freezer | Air at -30 to -40 °C | 150 to 200 mm |
In a hot climate choose the upper end of each range. For chiller rooms that means 100 mm in most Saudi locations. Freezer rooms standing in an uncooled warehouse or outdoors belong at 150 mm. Storage temperatures depend on your product, so confirm them with your supplier and the applicable SFDA requirements. For core materials, skins and joints see our guide to cold room panels.
Moisture and the vapour barrier
Warm air holds more water vapour than cold air. That vapour pushes toward the cold side through every gap. Even dry Riyadh air carries more moisture than the air inside a freezer. In humid Jeddah and Dammam the push is far stronger.
On a sandwich panel the metal skins are the vapour barrier. The weak points are joints, cut edges, screw holes and dents that break the skin. Vapour that reaches the foam condenses there. In a freezer it turns to ice. Wet or frozen foam conducts heat far better than dry foam and the growing ice forces joints apart.
The rule: the barrier must be continuous and it must sit on the warm side.
Thermal bridges: where the envelope leaks
A thermal bridge is any material that crosses the insulation and conducts heat better than foam. Check these places:
- Panel joints. A joint that is not pulled tight and sealed leaks heat and moist air together.
- Floor to wall junction. Wall insulation must meet floor insulation without a gap.
- Penetrations. Every pipe, cable, drain and bolt through a panel needs sealing on the warm side.
- Door frame. It is the busiest gap in the envelope. See our guide to choosing cold room doors.
- Steel supports and fixings that run from the warm side to the cold side.
The floor is part of the insulation
The ground under a building stays warm all year. A freezer without floor insulation pulls heat up through the slab day and night, so freezer rooms need an insulated floor. Under a large freezer built on the ground, the cold slowly freezes moisture in the soil and lifts the slab. Floor heating or ventilation under the slab prevents this frost heave. Freezer rooms also need a heated pressure relief valve, which stops pressure swings from pulling on panels and joints. See also freezer room design in Saudi Arabia.
Small chilled rooms are sometimes built on the existing floor. Make sure the heat load calculation includes that floor.
How insulation ages
Dry foam sealed between intact metal skins keeps its performance for many years. The parts around it fail first. Sealant hardens and cracks, fastest on sun-exposed walls. Daily temperature swings work the joints loose. Trolleys and forklifts dent or pierce the skins. Any moisture that got in keeps freezing and widens the damage.
Signs that insulation is failing
- Condensation or damp patches on outside walls or the ceiling, often in a line along a joint.
- Frost or ice lines along joints, around pipes or at the base of the walls inside a freezer.
- A panel skin that bulges or sounds hollow when you tap it.
- A freezer floor that lifts or cracks.
- A compressor that runs longer than last summer for the same stock and door traffic.
Long running hours have other causes as well, such as a dirty condenser, a frosted evaporator or worn door gaskets. Check those too with our guide to cold room energy efficiency.
Check your insulation in four steps
- Walk the outside. Look for sweating, damp patches, rust streaks and cracked sealant.
- Walk the inside. Look for frost lines at joints, penetrations, corners and the door frame.
- Tap suspect panels. A hollow sound points to a skin that has separated from the foam.
- Use a thermal camera. With the room at working temperature, cold spots on the outside face show where heat gets through. Lines mean joints. Patches mean a wet or damaged core. Scan after sunset, because sun-heated metal hides the pattern.
Repair options from small to large
- Re-seal joints and penetrations. Remove the failed sealant, dry the joint and seal again on the warm side.
- Patch pierced skins straight away so vapour stays out.
- Replace single panels that have a wet core. Ice inside foam does not dry out in a running freezer.
- Repair the floor or its heating when frost heave appears.
- Re-panel part of the room when damage is widespread.
Frequently asked questions
Can I use 100 mm panels for a freezer room?
That is below the typical 120 to 150 mm range. At the same temperatures a 100 mm panel passes about 50 percent more heat than a 150 mm panel. Its outside face also runs colder, which invites condensation in humid air. For a -18 °C room in Saudi heat, 150 mm is the sound choice.
Does a cold room inside an air-conditioned building need less insulation?
The heat load is lower, but the typical thickness ranges still apply. A freezer at -18 °C inside a 24 °C building faces a difference of 42 °C, about the same as a chiller standing outdoors in summer.
Why does ice form along the panel joints in my freezer?
Warm moist air is getting in at that joint and its moisture freezes where it meets the cold. The joint needs sealing on the warm side. Have the pressure relief valve checked too, because a blocked valve lets pressure swings pull air through the joints.
Can I add a second layer of insulation to an existing room?
Sometimes, for example when a chilled room is converted to a freezer. A second layer works when the existing panels are dry and sound and the warm-side face is sealed as the vapour barrier. Wet panels must come out first. The floor, door and refrigeration unit need upgrading too.
Insulation checks and upgrades with Cooliva
Cooliva is based in Riyadh and designs, supplies and installs cold rooms and freezer rooms across Saudi Arabia. Every new room begins with a requirement discussion and a site review, so the panel thickness and the floor build-up match your temperature and location. For an existing room with sweating walls, ice at the joints or long compressor hours, ask about our refurbishment and upgrade service. Send photos and your room temperature through the contact page or call +966 59 799 1000.
