A prefab house step by step: the order everything happens in (and when you pay for each part)

A prefab house step by step: the full order, from the town hall to the deed

These are the ten steps, in order:

1. 1Planning information on your plot, in writing (it is a right: article 5.d of the Land Law).
2. 2Buying the land, after checking the Land Registry extract and the cadastral reference (what to check on the land).
3. 3Soil study: the Basic Document SE-C of the Building Code puts it at the start of the project, because the foundations depend on it.
4. 4Stamped technical project and site management.
5. 5Building permit, with the ICIO and the fees.
6. 6Financing, if any.
7. 7Manufacturing in the factory and transport.
8. 8Foundations, assembly and utility connections.
9. 9Certificate of completion and first occupancy permit (or whatever replaces it in your region).
10. 10New-build deed before a notary, Land Registry and Cadastre.

Two doors cannot be forced: without a permit, work does not start, and without first occupancy there are no permanent utility connections and no deed for the finished building. What each permit requires is in what permits a prefab house needs.

Why the order decides the money

Because three laws tie each payment to a moment:

• •The permit has to be express, and if the town hall does not reply, the answer is no. Article 11.4.c of the Land Law requires it, with negative silence, for “placing prefabricated houses and similar installations, whether temporary or permanent”.
• •The ICIO is due when work starts, “even if the corresponding permit has not been obtained” (article 102 of the Local Finance Law). Starting early does not save you the tax: it adds a case file.
• •The guarantee on advance payments is born with the permit: the first additional provision of the Building Act requires it “from the moment the building permit is obtained”. Anything paid before that is left out, even in an ordinary off-plan purchase.

The price you see is not the price you pay

Before comparing prices, check what each one covers. A price can mean four different things, and each one is only compared with prices of its own type:

• •Kit, just the parts and the plans: median of €403/m² (132 houses from 8 manufacturers).
• •Shell only, without installations or full finishes: €649/m² (87 houses from 8 manufacturers).
• •Assembly extra, the whole house but not put together: €1,270/m² (68 houses from 11 manufacturers).
• •Turnkey, the finished house: €1,639/m² (137 houses from 21 manufacturers).

If a price does not say what it covers, ask in writing before comparing it. Each type, by material and by size, is in the price per m² comparison.

Three timber houses show it: Avrame's Duo 120 (in Spanish) is a kit for €18,848 that you assemble yourself; Naturmaderahogar's Guriezo (in Spanish) is put up for €44,800 (with assembly in Alicante and Murcia), without plumbing, electrics or foundations; and Casas de Madera Yustas' Julia Plus (in Spanish) arrives assembled and with its installations, turnkey from €63,635, but leaves out the foundations, the utility connections and the permit.

What hardly anyone tells you: you pay up front, without the law's safety net

When the house goes on your own plot, you are the developer. Article 9.1 of the Building Act defines the developer as whoever “decides, drives, plans and finances” the building work, including for themselves. The manufacturer is your contractor.

And the compulsory guarantee on advance payments (a bank guarantee or surety insurance, with the money in a separate account) is owed by whoever takes money from the buyers of a home, and it protects those buyers, not someone building their own house. Nobody is legally required to guarantee what you pay the manufacturer.

The risk is not theoretical: one in five companies that entered insolvency proceedings in 2025 belonged to the construction cycle (materials and real estate included), according to the Insolvency Yearbook of the Spanish Association of Registrars. A case from the sector: Modularis & Climad, a prefab house maker in Bergara, was set up in March 2020 with €3,000 of share capital and filed for voluntary insolvency in July 2023.

How to split the payments so you are not left without a house and without money

It is negotiated before signing, not after. Five things you can ask for:

• •A bank guarantee or surety insurance for each advance payment. The law does not require it of the manufacturer, but you can make it a condition of payment.
• •Payments by milestones you can check, not by dates: module finished in the factory, lorry loaded, house assembled, certificate of completion signed.
• •A retention of 5% of the construction cost during the first year after handover, which article 19.1.a of the Building Act provides for as an alternative to the finishing-defects guarantee.
• •The right VAT: a house permanently fixed to the ground is a home and pays 10%, like the building work you contract directly with whoever builds it; if it can be moved without being broken, the tax authority applies 21% (ruling V5259-26 of the Directorate-General for Taxation, July 2026).
• •The manufacturer's health in the Companies Register (filed accounts, age and share capital) before the first payment. Start with the manufacturers directory.

The order changes depending on what you buy

What you buy does not change the procedures, but it does change who pays for what and when:

• •Turnkey: fewer contracts and fewer separate payments, but few houses include the permit in the price (41 of 189 with a turnkey price). And even if the manufacturer handles it for you, you are still the developer.
• •Kit, shell or assembly extra: each missing item is another supplier and another payment (assembler, foundations, installations), and coordinating the order becomes your job.
• •Mobile homes: wheels do not change the order. The Supreme Court treated them as prefabricated houses in its ruling of 5 December 2024, and they need the same permit.

How the house arrives also matters: in finished modules it is placed in a few days; put up piece by piece on the plot, the works take longer, and so do the payments against construction certificates.

Permit deadlines: what is the same across Spain and what is not

There is no single deadline in Spain for the building permit of a home: each region's planning law sets it and, within it, your town hall. What they all share:

• •If the rules set no deadline, it is 3 months (article 21.3 of Law 39/2015), and none exceeds 6 unless a law says so (article 21.2).
• •The clock stops every time you are asked to correct documents (article 22.1.a).

Manufacturing and assembly come on top: they are in how long a modular house takes. And if you are going to finance it, first read how a mortgage for a prefab house works: a self-build mortgage is paid out against construction certificates, and that sets your payment schedule.