Useful articlesReading time ~6 minPublished 09.10.2026

How to insulate a shipping container

When a container needs insulation, which material to choose and how to avoid condensation behind the insulation.

In short

Storage containers usually do not need insulation; a workshop, office or sensitive goods do.
PUR spray foam or tightly sealed PIR boards suit containers best — they keep moisture away from the steel.
Start with the ceiling — that is where most condensation forms.
Choose a High Cube container for insulating: it is 30 cm taller.

When a container needs insulation

For belongings, tools and machinery, insulation is usually not needed — ventilation and raising the container off the ground are enough. Insulate if the container will be a workshop, an office, storage for sensitive goods or a space where people spend time.

Steel heats up and cools down quickly, so an uninsulated container is hot in summer, cold in winter and gets condensation on the ceiling. Proper insulation solves all three. More on condensation in the article shipping container condensation.

Types of insulation

How well it suits a container

PUR spray foamSticks to the corrugated steel, fills every gap and acts as a vapour barrier at the same time. More expensive and needs professional application.

Rigid foam boards (PIR, XPS)Insulate well at a small thickness. Every seam and cut-out must be sealed carefully, or condensation forms behind the boards.

Mineral wool in a frameEasy to get, non-combustible and good for sound, but does not stop moisture on its own — it needs a vapour barrier, and the frame takes space.

Reflective foilOnly as an addition — on its own it protects neither against cold nor condensation.

The key rule: warm, humid room air must not reach the cold steel. If it does, condensation forms behind the insulation where you cannot see it, and the container starts rusting from the inside.

How to insulate — the main steps

Prepare the surface. Clean off dirt and treat rust spots — once insulated, you cannot reach them.
Cut-outs first. Fit windows, doors, vents and electrical entries before insulating.
Start with the ceiling. The roof is heated most by the sun during the day and cooled most at night — that is where most condensation forms.
Insulate the walls and doors. The doors are a large steel surface too; if you do not use them daily, they can be insulated together with the wall.
Vapour barrier and seams. With wool, fit a vapour barrier on the inside; seal board seams with foam or tape.
Floor. If people will spend time inside, insulate the floor too — on top of the existing floor or under the container.
Ventilation. An insulated container still needs air exchange, or moisture from people and work stays inside.

How much space is left inside

A standard container is ~2.35 m wide and ~2.39 m high inside. Framed insulation takes space from both walls and the ceiling, so in a standard container the ceiling gets low. A High Cube container is ~2.70 m high inside — after insulating, the ceiling is still at a comfortable height. Spray foam takes less space than a frame with wool. Exact dimensions are in the shipping container size table.

The alternative: a ready insulated module

If you need a warm room for an office or security staff straight away, a conversion can cost more time and money than a ready module. Our office containers have walls and a roof of 50 mm sandwich panels and a floor insulated with 100 mm of stone wool — you can use them right after delivery.

Common mistakes

Putting wool directly against the steel without a vapour barrier.
Insulating the walls but not the ceiling.
Forgetting ventilation — an insulated container “sweats” on the inside.
Not treating rust before insulating.
Insulating a standard-height container and ending up with a low ceiling.

Which container to choose for insulating

A new one-way High Cube container is the best base for a conversion — dry, straight walls without rust and a ceiling 30 cm higher. A used container also works if it is dry and has no rust-through; how to check is in the article how to choose a used shipping container.

Frequently asked questions

Can a shipping container be insulated?

Yes. Containers are insulated from the inside with PUR spray foam, PIR boards or mineral wool in a frame. The key is to stop warm, humid air from reaching the cold steel.