Structural-Defect & Décennale Insurance on New-Builds Abroad (2026): The 10-Year Warranty Guide

Published on: June 15, 2026

Quick answer: When you buy off-plan, new-build, or self-build abroad, the building can be defective from birth, and most civil-law countries answer that with a 10-year structural warranty. France runs the gold standard (the builder's décennale plus the owner's dommage-ouvrage, which pre-funds repairs without proving fault); Spain's seguro decenal is mandatory and notaries block the sale without it; the UK's NHBC Buildmark is lender-required in practice; Italy's decennale postuma applies to off-plan. The rule everywhere: demand the paid-up certificate, not just a legal principle.

When you buy an off-plan apartment, a new-build villa, or commission a self-build abroad, you face a risk that does not exist when you buy an old stone farmhouse: the building might be defective from birth. A crack in the foundations, a roof that isn't watertight, a load-bearing wall that wasn't built to spec, these can surface years after you move in, long after the developer has banked your money and moved on. The protection against that risk has a name in every civil-law country, and most foreign buyers have never heard of it until something goes wrong.

This is the natural companion to off-plan deposit protection. Deposit guarantees protect your money before completion; structural-defect insurance protects the building for years afterwards. Here is how the major 10-year warranty systems work in 2026, and what to check before you sign.

France, the gold standard: décennale + dommage-ouvrage

France runs the most developed structural-defect regime in the world, established by the Loi Spinetta of 1978 and built on two complementary policies.

The garantie décennale is a compulsory 10-year warranty that the builder must carry. It works on a tiered basis: in year one, the builder guarantees complete performance of the work (garantie de parfait achèvement); through year two, that fittings and equipment function (garantie de bon fonctionnement); and for the full ten years from completion, the structural and watertightness elements, foundations, walls, floors, roof, framework (l'assurance décennale). A powerful feature for the owner: when a covered defect appears, you do not have to prove fault, the builder is presumed responsible.

The second policy is the one buyers most often skip and most regret skipping: dommage-ouvrage (DO), taken out by the person commissioning the work. DO pre-funds the repair without waiting for the courts to establish whose fault the defect is, it pays out first and then recovers from the builder's décennale insurer. It also covers contractor abandonment. DO is legally required for the maître d'ouvrage (and costs roughly a few percent of the build), though enforcement is weak. The trap is selling within ten years: if you commissioned a build and never took DO, a buyer's lawyer can flag the gap and stall or reprice the sale. If you are buying a recent new-build, ask for the dommage-ouvrage certificate, not just the builder's décennale.

Spain, seguro decenal: mandatory and sale-blocking without it

Spain's equivalent is the seguro decenal, made compulsory by the Building Regulation Law (LOE, Law 38/1999). It is a 10-year structural insurance that the developer or builder takes out and that transfers to the buyer on sale. It covers serious structural defects, foundations, load-bearing walls, beams, that threaten the building's stability, running for ten years from completion and the granting of the occupancy licence (Licencia de Primera Ocupación).

The crucial procedural point: a developer must provide a certificate proving the seguro decenal is in place before selling a new home, and notaries and registrars require that certificate to complete and register the sale. So for a new-build in Spain, the structural warranty is not optional paperwork, it is a gatekeeper to the transaction itself. If a developer is evasive about the decenal certificate, treat it as a serious red flag.

United Kingdom, NHBC Buildmark and its rivals

The UK takes a contractual rather than statutory route. The dominant product is NHBC Buildmark, a new-home warranty that typically provides a builder defects period in the first two years (the builder fixes faults) and structural insurance cover for years three to ten (the warranty provider covers major structural problems). It is not legally mandatory, but in practice mortgage lenders require a recognised 10-year warranty (Buildmark, or an alternative such as LABC Warranty or Premier Guarantee) before they will lend on a new build, which makes it effectively essential. For a foreign buyer financing a UK new-build, no warranty often means no mortgage.

Italy, decennale postuma: real, but thinner

Italy has a structural-defect regime, but it is less protective than France's. Under the Civil Code, Article 1669 holds the builder liable for ten years for serious defects affecting the building's stability, with a shorter two-year window (Art. 1667) for lesser defects. For off-plan buyers specifically, the law (Dlgs 122/2005) requires the developer to provide a decennale postuma, a 10-year structural insurance policy, alongside the deposit-guarantee bond (fideiussione) that protects your stage payments.

The practical reality is that Italian structural protection leans more on the builder's liability than on a robust, automatically-funded insurance product, and enforcement can mean litigation. For a foreign buyer, the action is the same as elsewhere: insist on seeing the decennale postuma policy for an off-plan purchase, and don't accept "the builder is liable by law" as a substitute for a paid-up insurance certificate.

10-year structural warranties compared (2026)

What every new-build buyer should do

The pattern across all four markets is identical, even though the legal machinery differs. First, the warranty attaches to the building, not to you, so it transfers on resale, and when buying a recent new-build you should confirm the certificate exists and check how many of the ten years remain. Second, a paper certificate beats a legal principle, "the builder is liable" is worth far less than a paid-up, transferable insurance policy you can claim against. Third, in France specifically, don't confuse the builder's décennale with your dommage-ouvrage, you want both. Verify the structural-defect cover with your local lawyer at the same time you verify the deposit protection; they are the two halves of buying new safely.

Frequently asked questions

What is décennale insurance in France?
A compulsory 10-year structural warranty the builder must carry, covering stability and watertightness defects without the owner having to prove fault. The owner can add dommage-ouvrage to pre-fund repairs.

Is structural-defect insurance mandatory on new-builds in Spain?
Yes, the seguro decenal is required under the LOE for new residential buildings, taken out by the developer, transferred to the buyer, and required by notaries before completion.

What is NHBC Buildmark?
The UK's most common new-home warranty: a builder defects period in years one to two and structural insurance for years three to ten. Not legally mandatory, but lenders generally require a recognised warranty.

Does a 10-year warranty transfer when I sell?
Generally yes, it attaches to the building, so the remaining term passes to subsequent owners. Always confirm the certificate and the years remaining on a recent resale.

The other half of buying new

Structural-defect cover is the other half of buying new, the first half is protecting your deposit before completion. See The Preliminary Contract Deposit Trap. JanusHermes breaks down new-build and off-plan due diligence across 50+ markets, explore listings and country intelligence on JanusHermes.

This guide is general information, not legal or insurance advice. Always have a qualified local lawyer verify the structural-defect cover before completing a new-build or off-plan purchase.