Contentar · FAQ
For an independent home, yes: full planning permission from the council, plus Building Regulations approval, which is a separate process. In England the planning fee for one house is £610 (since April 2026) and the council has 8 weeks to decide.
Scotland (£742) and Wales (£667) have their own fees, and Scotland uses a building warrant instead of building control approval.
Sometimes, as a caravan. A unit of up to 2 sections, movable on the road in one piece, within 20 × 6.8 m and 3.05 m internal height, can stand in the garden without planning if it is used as part of the main house: a guest room, an office, a place for a relative.
If it becomes an independent home (its own address, meters, access or parking), it needs planning permission. A structure on a concrete base with fixed connections, or one that must be taken apart to move, is a building. We found no published decision on a converted shipping container as a caravan: get a Lawful Development Certificate (about £300) before you rely on it.
A Class E outbuilding can be built without planning, but it cannot have a bedroom, bathroom or kitchen, is limited to 4 m in height (2.5 m within 2 m of a boundary) and to half the garden. It works for a garden office or gym, not for somewhere to sleep.
Where the council applies the Nationally Described Space Standard, a 1-bedroom home for one person needs 37 m² and for two people 50 m². A 40 ft High Cube gives about 28 m²: as an independent home it falls short.
Two 40 ft containers (about 54 m² usable) meet the standard for a 1-bedroom, 2-person home. The 2.3 m minimum ceiling height is met by an insulated High Cube.
The build can take a few weeks to about 6 months. Planning takes at least 8 weeks once the application is valid, often more, and Building Regs approval runs alongside.
Allow 6 to 12 months from the first drawings to the completion certificate. That is our own estimate, not an official figure.
It is the hardest part. For homes under 10 years old, lenders usually want a new home warranty or a Professional Consultant’s Certificate. We could not confirm that NHBC, LABC or Premier cover converted containers.
Speak to a mortgage broker who handles self-build and non-standard construction before you buy the land.
For a home, used only if grade A and after an inspection: structural rust, the floor (often treated with chemicals) and the door seals. A one-trip container costs more, but in the UK a 40 ft High Cube one-trip is around £3,000 plus VAT.
The difference barely matters in the total: the container is under 10% of the bill.
Per m², not always. Self-build in the UK averages £2,200 to £3,000 per m²; our 1-bedroom estimate comes out around £1,500 per m², without land. The real saving comes from a shorter build and a simple plan, not from the price of steel.
Containers, delivery, foundations, cuts, insulation, windows, services, bathroom, kitchen, furniture, planning, building control, architect and engineer, VAT at 20% and a ±15% margin. It never includes the land.
It does not yet include a heat pump, solar panels, a warranty, CIL or stamp duty on the land.
A qualifying new dwelling built by a VAT-registered builder can be zero-rated, and self-builders can reclaim VAT on materials through the DIY housebuilders scheme, within 6 months of completion.
An annexe that cannot be used or sold separately pays 20%. Architect’s fees always pay 20%. Residential caravans to BS 3632 are zero-rated. The calculator uses 20% throughout: ask an accountant before you sign.