The basic cost structure
Anyone converting a container into an office, workshop, retail space or habitable room almost always underestimates the ratio. A used 20-foot container might cost €2,500. A full fit-out of that same container costs several times as much.
The reason is mundane: a fit-out involves exactly the same trades as any other building – insulation, electrics, plumbing, heating, windows, doors, finishes. The small areas do not make the work cheaper; proportionally they make it dearer, because set-up times, travel and minimum quantities spread across just a few square metres.
| Cost block | Share of the total (rough) |
|---|---|
| Container shell | approx. 15–25% |
| Insulation and internal lining | approx. 15–25% |
| Windows, doors, openings | approx. 10–20% |
| Electrical installation | approx. 10–15% |
| Plumbing, where present | approx. 10–20% |
| Heating and ventilation | approx. 5–15% |
| Floor and finishes | approx. 8–12% |
| Foundation and connections | approx. 5–15% |
Adding a sanitary unit shifts everything: plumbing is the most expensive trade per square metre in a container, because supply and waste have to be routed through a steel wall, laid frost-proof and connected to the site network.
Trade by trade
The figures below apply roughly to a 20-foot container with around 14 m² of floor area and assume work by trade contractors. For self-build, see further below.
Cutting and reinforcing openings
| Item | Rough cost |
|---|---|
| Cutting a window opening, welding in a frame | approx. €400–900 per opening |
| Cutting and reinforcing a door opening | approx. €500–1,200 |
| Supplying and fitting a window, uPVC, double glazed | approx. €500–900 each |
| Window, triple glazed, high quality | approx. €800–1,500 each |
| External door, insulated, with frame | approx. €900–2,000 |
| Roller shutter or grille | approx. €300–800 per opening |
Welding in frames is not optional luxury. The steel of a container is load-bearing; every large opening weakens the structure and must be replaced by a surrounding profile. For permit-required projects the structural engineer will insist on it anyway.
Insulation and lining
| Item | Rough cost |
|---|---|
| Internal mineral wool incl. sub-frame and vapour control layer | approx. €60–110 per m² of component area |
| Internal PUR/PIR boards | approx. €70–130 per m² |
| Spray foam by a specialist contractor | approx. €40–90 per m² |
| External insulation system with cladding | approx. €120–220 per m² |
| Plasterboard lining, filled and taped | approx. €35–60 per m² |
| Wood-based or exposed timber lining | approx. €50–120 per m² |
For a 20-foot container there are roughly 60 to 70 m² of component area to insulate once walls, ceiling and floor are added together. At €85 per square metre the insulation alone reaches around €5,500. This is the item that regularly causes surprise at the first quote.
Whether to insulate internally or externally determines interior dimensions and building physics alike; the trade-off is set out in Insulating a container and Thermal bridges in shipping containers.
Electrical installation
| Item | Rough cost |
|---|---|
| Basic installation, 20 ft container, trade contractor | approx. €1,800–4,000 |
| Consumer unit with RCD and breakers | approx. €400–900 |
| Socket, switch, outlet, each | approx. €60–130 |
| LED ceiling light, fitted | approx. €90–250 each |
| External connection with CEE socket | approx. €250–600 |
| Earthing and equipotential bonding of the steel body | approx. €200–500 |
| Electrical inspection / test certificate | approx. €150–400 |
Two particularities push the price above that of a masonry room: the steel body must be earthed and included in equipotential bonding, and every cable penetration through sheet steel needs a proper grommet. Improvised solutions here are a typical cause of fire, see Fire safety for containers.
Plumbing
| Item | Rough cost |
|---|---|
| WC with hand basin, complete | approx. €2,000–4,500 |
| Shower in addition | approx. €1,500–3,500 |
| Small kitchen unit with connections | approx. €1,500–4,000 |
| Hot water, instantaneous heater | approx. €400–1,200 |
| Supply and waste pipework, laid frost-proof | approx. €80–200 per linear m |
| Connection to sewer or small treatment plant | approx. €1,500–8,000 |
| Waste water tank as an alternative | approx. €800–2,500 plus emptying |
The range for the sewer connection is the biggest uncertainty in the whole project. If the connection is ten metres away it stays manageable; if it is on the other side of the road it runs into five figures. Clarify this before buying the container, not afterwards.
Heating and ventilation
| Item | Rough cost |
|---|---|
| Electric infrared or convector heating | approx. €300–900 |
| Split air conditioner with heat pump function | approx. €1,500–3,500 incl. installation |
| Small air-to-water heat pump | approx. €6,000–14,000 |
| Wood or pellet stove incl. flue | approx. €3,000–7,000 |
| Passive ventilation grilles | approx. €20–80 each |
| Extract fan with humidity control | approx. €150–500 |
| Decentralised ventilation with heat recovery | approx. €800–2,000 per unit |
A split unit with heat pump function is the practical standard for containers: it heats, cools and dehumidifies, is easy to size for the small heat load and satisfies the energy law requirements for renewable heat; see The GEG and containers. For ventilation planning see Container ventilation.
Floor and finishes
| Item | Rough cost |
|---|---|
| Removing and disposing of the original container floor | approx. €400–1,000 |
| New floor build-up with insulation and board | approx. €60–120 per m² |
| Vinyl or design flooring, laid | approx. €35–70 per m² |
| Tiling in wet areas | approx. €70–150 per m² |
| Internal decorating | approx. €15–35 per m² |
| External painting of the container | approx. €25–60 per m² |
The first item is frequently overlooked: the original plank floor of shipping containers is usually treated with insecticides and fungicides. For habitable rooms it is therefore normally removed or permanently sealed over – an extra item that appears in no sales brochure.
Worked examples
Simple office room, 20 ft, no plumbing, trade contractors
| Item | Amount |
|---|---|
| Used container, wind and watertight | approx. €2,600 |
| Transport in, placement | approx. €600 |
| Point foundations | approx. €900 |
| Two windows and one door, incl. welded frames | approx. €4,200 |
| Insulation and internal lining | approx. €6,500 |
| Electrical installation | approx. €2,800 |
| Heating, split unit | approx. €2,400 |
| Floor build-up and covering | approx. €2,000 |
| Decorating | approx. €900 |
| Total | approx. €22,900 |
That works out at roughly €1,600 per square metre – a figure that surprises most people but is realistic compared with conventional construction.
Habitable room with WC and kitchenette, 20 ft, trade contractors
| Item | Amount |
|---|---|
| Basic fit-out as above | approx. €22,900 |
| WC with hand basin | approx. €3,200 |
| Kitchenette with connections | approx. €2,600 |
| Hot water generation | approx. €700 |
| Pipework and connection to existing sewer, 12 m | approx. €2,400 |
| Tiling and waterproofing the wet area | approx. €1,500 |
| Total | approx. €33,300 |
Self-build of the same office room
| Item | Amount |
|---|---|
| Container, transport, foundation | approx. €4,100 |
| Windows and door, materials, welding contracted out | approx. €2,600 |
| Insulation materials, sub-frame, boards | approx. €2,300 |
| Electrical materials, connection and certification by a contractor | approx. €1,400 |
| Heating, split unit incl. installation by a contractor | approx. €2,400 |
| Flooring and paint, materials | approx. €1,100 |
| Total materials and bought-in work | approx. €13,900 |
The saving is around 40 per cent – bought with roughly 150 to 250 hours of work. What you generally cannot do yourself: the electrical connection and certification, refrigerant work on the split unit, gas work, and anything requiring building control verification.
Where costs run away
| Cause | Typical additional cost | Prevention |
|---|---|---|
| Sewer connection further away than assumed | €3,000–10,000 | check before buying |
| Turns out to need a permit after all | €2,000–8,000 for design and verifications | file a pre-application enquiry |
| More rust on the shell than visible at purchase | €1,000–4,000 | inspection, condition grade, photos |
| Internal instead of external insulation | loss of approx. 15% of floor area | decide early |
| Crane needed instead of roll-off | €500–1,500 | check the position |
| Layout changed after work starts | €1,000–5,000 | finish the design before building |
| Original container floor has to come out | €400–1,000 | budget for it from the start |
Important note
All prices are rough orientation values without guarantee and refer to typical conditions in Germany. Trade rates vary considerably by region, material prices change continuously, and the actual effort depends heavily on the condition of the container and local circumstances. Only individual quotes are binding. Electrical, gas and refrigerant work as well as building control verifications are reserved for qualified contractors and planners.
Conclusion
In a container fit-out the container is the smallest item. For a professionally executed office room without plumbing, budget roughly €20,000 to €26,000 at 20 feet; with a sanitary unit more like €30,000 to €40,000. The largest uncertainties are the sewer connection and the permit question – both should be settled before the container is bought. Self-builders realistically save around 40 per cent but still have to contract out the electrical connection, refrigerant work and verifications.
Further reading: Converting a residential container, Insulating a container and Tiny house costs.