A steel shipping container sweats in the cold and heats up to over 50 °C in the sun. If you use it as an office, workshop or storage for sensitive goods, you can't avoid insulation . This page shows which materials are suitable, what the layer structure looks like and where the most common mistakes occur. If you want to save yourself the effort, buy a factory-insulated insulated containers.
Interior or exterior insulation?
The Interior insulation is the usual choice: easy to implement, but it costs interior space (5–10 cm per wall). That is why the High Cube is recommended as a base. The exterior insulation preserves the interior space and protects the steel, but is considerably more complex and requires facade cladding.
Insulation materials compared
| Material | Insulation value | Moisture behaviour | Effort | Note |
|---|---|---|---|---|
| PU in-situ foam (sprayed) | very good | vapour-tight | specialist contractor | seamless, follows every contour, no thermal bridges |
| PU/PIR boards | very good | vapour-tight | medium | high insulation performance at low thickness, tape joints carefully |
| Mineral wool | good | vapour-permeable, moisture-sensitive | medium | inexpensive, non-combustible, requires a vapour barrier |
| Rubber / Armaflex | good | vapour-tight | low | self-adhesive, ideal for the ceiling and hard-to-reach areas |
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Which material for what?
For an unheated storage unitthat only needs to dampen temperature peaks, rubber or a thin PIR board is the pragmatic choice – quick to install, hard-wearing, no need for a vapour barrier. For a living or work space the way forward is PU in-situ foam or carefully bonded PIR boards: only these achieve the required insulation performance within the limited build-up thickness in a container and are airtight at the same time. Mineral wool is inexpensive and non-combustible, but requires a flawlessly executed vapour barrier – in practice the most common cause of damage. Where there are fire protection requirements (rental, commercial use, assembly rooms), it is not the insulation value that decides, but the building material class: in that case mineral wool is often the required choice despite the extra effort.
Thermal bridges at the steel frame
The continuous steel profiles at the floor, ceiling and corners conduct heat directly to the outside – this is where condensation forms first. The insulation layer must therefore lie continuously in front of the steel, without interruption by a counter-batten that touches the steel. It is best to insulate directly onto the steel (in-situ foam or bonded boards) and only place the battens on top of the insulation.
Moisture and vapour barrier
With vapour-permeable materials (mineral wool), a vapour barrier must be installed on the room side so that no humid room air migrates into the insulation and condenses there. With vapour-tight materials (PU, rubber), the material itself acts as the barrier – what matters then is airtight bonding of all joints. Related topic – condensation: Avoiding condensation in containers.
Layer structure from inside to outside
Interior lining (e.g. OSB, plywood) → services layer / battens → vapour barrier (with vapour-permeable insulation) → insulation → steel wall. Floor and ceiling are built up separately; the floor often gets additional build-up insulation under the new flooring.
Don't forget the floor and ceiling
The Floor is the most difficult part: the original film-faced plywood floor lies directly on the cross members, beneath which air circulates. Either insulate from below (complex, but with no loss of height) or build a new structure on top of the existing floor – insulation between joists, with the new wear layer on top. The latter costs 5 to 8 cm of headroom, which is another reason to choose the High Cube as a base. The ceiling has its own geometry with the corrugated roof sheet and the rainwater groove; here, in-situ foam or self-adhesive rubber has a clear advantage over boards, which would have to be fitted to every corrugation.
Which insulation thickness for which purpose?
- Storage for temperature-sensitive goods: 4–6 cm is enough to dampen temperature peaks.
- Break room / office: 6–10 cm; for permanent use, the requirements of the Building Energy Act (GEG) apply.
- Residential use: as with new construction – the thermal insulation is planned by a specialist company. More on this: Residential container.
Do it yourself or hire a specialist company?
Simple rubber or board insulation for a storage container is easy to do yourself. As soon as it involves occupied rooms, airtight construction and proof of GEG compliance, the conversion should be left to specialists. Coin Container carries out insulation and interior fit-out in its own workshop: Container conversion and modification.
Common mistakes
- Insulation interrupted at one point (thermal bridge, condensation)
- no vapour barrier with vapour-permeable insulation
- insulation too thin – the container stays hot in summer
- forgetting the floor and ceiling
Frequently asked questions
How thick should the insulation in a container be?
4–6 cm is enough to dampen temperature peaks in a storage container. For a permanently occupied room, 6–10 cm is common.
Is insulation without a vapour barrier sufficient?
Only with vapour-tight materials such as PU or rubber, which provide the barrier function themselves. With mineral wool, a vapour barrier is mandatory.
How much interior space does the insulation take up?
With interior insulation, usually 5–10 cm per wall – which is why the High Cube, with its additional interior height, is often a good base.
Can I insulate a container myself?
For a simple storage container, yes. As soon as occupied rooms, airtightness or proof of GEG compliance are required, the work should be left to specialists.
Next
Converting shipping containers – ideas and costs · Container guide · Request a quote
Zuletzt aktualisiert: 7. November 2026 · Redaktion: Coin Container Team, Hamburg