Cold Rooms & Freezer Stores — Sandwich Panel Selection and Insulation Requirements

Building a cold storage facility is one of the most demanding challenges in sandwich panel installation — errors in insulation thickness selection or gaps in the vapour barrier can cost operators tens of thousands of euros every year in energy losses. This article covers specific thermal requirements, PIR panel selection criteria, and the standards that apply across the DE, NL, BE, and AT markets.

Thermal Requirements: U-Value and Insulation Thickness

For cold rooms operating in the 0°C to +4°C range, the standard wall U-value requirement is no higher than 0.25 W/m²K. In practice, this means a PIR panel with a minimum thickness of 120 mm, assuming a thermal conductivity of λ = 0.022 W/mK. For freezer stores operating at -18°C to -25°C, the requirements increase significantly.

When designing freezer stores, we target a U-value below 0.15 W/m²K for walls and 0.12 W/m²K for the roof. This translates to a panel thickness of 200–250 mm. The roof always requires greater insulation than the walls, as heat loss through a horizontal surface is proportionally higher when there are large temperature differentials.

Facility Type	Operating Temperature	Required U-Value (Wall)	Min. PIR Thickness
Fresh cold room	0°C / +4°C	≤ 0.25 W/m²K	120 mm
Deep cold room	-10°C / -15°C	≤ 0.18 W/m²K	160–180 mm
Industrial freezer store	-18°C / -25°C	≤ 0.15 W/m²K	200–250 mm
Freezer store roof	-18°C / -25°C	≤ 0.12 W/m²K	250–300 mm

U-value calculations must account for thermal bridges at panel joints, fasteners, and corner zones. On our DE market projects, we always apply a +10–15% correction to the nominal U-value declared by the manufacturer to cover real-world losses at connections.

PIR Core vs. Other Insulation Materials

In cold storage construction, the PIR (polyisocyanurate) core dominates — and for good reason. With λ = 0.022–0.023 W/mK, it offers the best insulation-to-thickness ratio of any available solution. PUR achieves similar performance but has a higher fire risk. Mineral wool, to meet the same U-values, would require panels of 200–280 mm in typical cold storage applications, which is uneconomical in many cases.

Insulation Core Comparison for Cold Storage

Core	λ (W/mK)	Fire Classification	Indicative Price (EUR/m²)
PIR	0.022–0.023	B-s1, d0 / C-s2, d0	28–45 EUR/m²
PUR	0.023–0.025	D-s3, d0 / E	22–36 EUR/m²
Mineral wool	0.033–0.040	A1 / A2-s1, d0	38–62 EUR/m²

A number of proven premium-grade products are available on the market: Kingspan KS1000 RW with a PIR core, Isopan Isobox designed specifically for refrigerated applications, Ruukki Energy widely used in Scandinavian projects, and ArcelorMittal Arval panels in the Isovar system. All of these systems carry certification to EN 14509 — the mandatory standard for sandwich panel procurement in the European market.

Vapour Barriers and Condensate Management

The vapour barrier is the most frequently overlooked element in cold storage projects. With an external temperature of +20°C and 70% relative humidity, and an internal temperature of -18°C, the dew point falls deep within the building envelope. Without an effective vapour barrier, moisture condenses within the insulation structure, reducing its thermal performance by 20–40% over just a few seasons.

Key principle: In freezer store facilities, the vapour barrier must always be installed on the warm side of the building envelope — any error in its positioning leads to insulation degradation and corrosion of the steel facings, which cannot be remedied without a full panel strip-out.

The standard in our NL and DE projects is an internal facing with a polyurethane or PVDF coating at a minimum thickness of 0.5 mm, with joints sealed using vapour-tight tape rated at Sd ≥ 100 m. Alternatively, we use panels with a galvanised steel facing combined with 200 µm PE membranes applied at the joints.

• Vapour-tight tapes: use only products with a declared Sd ≥ 100 m (e.g. SIGA Fentrim, Pro Clima Tescon)
• Horizontal joints on wall panels must be sealed on the warm side before the next layer is installed
• Internal corners and service penetrations are critical points — double sealing is required
• Check airtightness before commissioning the refrigeration unit: pressure test or IR thermography
• In AT and DE freezer stores, vapour barrier documentation is required by DGUV as a condition of project sign-off

Fire Classifications — Requirements in DE, NL, and AT

Fire safety requirements for cold storage facilities vary by country and building class. In Germany (MBO / LBO), storage facilities exceeding 3,600 m² in floor area require a minimum reaction-to-fire classification of B-s1, d0 to EN 13501-1 for facing materials. In Austria, ÖNORM B 3800 sets out similar requirements, with additional provisions for roof coverings.

For facilities with loading docks or compressor rooms in the DE market, fire resistance classification of separating walls is required — typically a minimum of REI 60 for fire compartment walls. A sandwich panel with a PIR core does not achieve REI 60 on its own — it requires cladding with glass-fibre gypsum board or Knauf Aquapanel.

• EN 14509 — product standard for sandwich panels; a Declaration of Performance (DoP) is mandatory
• EN 13501-1 — reaction-to-fire classification: A1, A2-s1, B-s1, C-s2
• REI 30 / REI 60 / REI 90 — fire resistance of separating elements, required for compartment walls
• DGUV Vorschrift 20 (DE) — health and safety regulations for refrigeration facilities, influencing material selection
• DIN 18516 — ventilated facades, applicable where a cold storage panel is exposed as a facade element

Cold Storage Panel Installation — Schedule and Costs

A standard installation project for a cold room with a floor area of 1,000 m² (walls and roof) takes our team 10–14 working days, assuming the steel structure is ready. A freezer store of the same size, given the airtightness and panel thickness requirements, extends to 16–20 days. The programme always includes 1–2 days for airtightness testing prior to handover.

Labour costs for cold storage panel installation in the DE and NL markets range from 18–28 EUR/m² for walls and 22–35 EUR/m² for the roof, depending on panel thickness and the complexity of the detailing. Material costs for a 200 mm PIR panel run at 38–52 EUR/m² net for orders above 500 m². Projects below 300 m² are proportionally more expensive — labour rates rise to 32–42 EUR/m² due to fixed mobilisation costs.

Typical Stages of a Cold Storage Project

1. Design review and panel selection — verification of U-value, fire class, and compatibility with the refrigeration system (3–5 days)
2. Order and delivery — standard lead times for cold storage panels: 4–8 weeks from order placement
3. Substrate preparation — checking the flatness and plumb of the steel structure; tolerance max. ±5 mm/3 m
4. Wall panel installation — bottom to top, with level checks every 3 rows
5. Roof panel installation — accounting for water run-off direction and rooflight positions
6. Sealing and vapour barrier installation — a critical stage requiring a separate sign-off by the site manager
7. Testing and handover — IR thermography, airtightness report, DGUV documentation where required

Key Takeaways

Selecting the right panels for a cold storage facility demands precision at every stage — from the thermal design through to vapour barrier sign-off. Mistakes made during installation are costly and difficult to rectify without stripping out entire wall or roof sections.

• For a -18°C freezer store, specify a PIR panel of at least 200 mm (roof: 250–300 mm) and verify the U-value with a thermal bridge correction applied
• Always install the vapour barrier on the warm side — use tapes rated Sd ≥ 100 m and document every joint in line with DGUV requirements
• Require an EN 14509 certificate and Declaration of Performance (DoP) from the panel manufacturer before placing your order
• Plan panel deliveries 4–8 weeks in advance — production delays are the most common cause of programme overruns on cold storage projects