A structural warranty is one of those things that sits in a filing cabinet and gets ignored until something goes seriously wrong. At that point, whether you have one or not makes an enormous difference.
Most people building or buying a new home know they need a structural warranty because their mortgage lender requires it. Far fewer actually understand what it covers, what it does not cover, how the claim process works, or what happens if they try to sell a home that does not have one.
This guide explains how structural warranties work in plain terms. It covers what is included, the difference between the defects period and the insurance period, which providers are worth knowing about, how much it costs, and what your options are if you are self-building. If you are concerned about what happens if your builder goes bust, our guide on contractor insolvency covers how a warranty fits into that picture.
What Is a Structural Warranty?
A structural warranty is a 10-year insurance-backed policy that protects a new home against significant defects in its design, materials, or workmanship. It is taken out by the builder or developer before or during construction, but it protects the homeowner, not the builder.
The policy stays with the property, not with the original buyer. If the home is sold within the 10-year term, the remaining cover transfers automatically to the new owner. This is one of the reasons mortgage lenders and conveyancing solicitors insist on it: it protects whoever owns the property, not just the person who commissioned the build.
You will hear these policies described by several different names: structural warranty, building warranty, new build warranty, latent defects insurance, inherent defects insurance. They all refer to the same thing. The name varies by provider and context but the purpose is the same.
How the Two-Period Structure Works
Every structural warranty is split into two distinct periods that work differently. Understanding this split is essential because the cover you have in years one and two is meaningfully different from the cover you have in years three to ten.
Years 1 and 2: the builder’s defects period
In the first two years after practical completion, the builder is responsible for fixing defects. If a window does not seal properly, a door frame is out of square, plaster cracks appear, or the heating system does not work as it should, you report it to the builder and they are obliged to put it right.
The warranty provider does not pay for repairs in this period. Their role is to act as a backstop if the builder disputes your claim, drags their feet, or goes out of business. Most providers have a resolution service that you can escalate to if you and your builder cannot agree. If the builder is insolvent, the warranty provider steps in directly.
Most defects in a new build show up in the first two years. This is the period when the building settles, materials dry out, and any workmanship problems become visible. Report every defect in writing during this period and keep records of what was reported and when.
Years 3 to 10: the structural insurance period
From year three onwards, the builder’s obligation ends and the insurance policy takes over. But the cover changes significantly. You can no longer claim for general defects or workmanship problems. The policy now only covers major structural issues: damage to load-bearing elements caused by a failure to build to the warranty provider’s technical standards.
What counts as structural varies slightly between providers but typically includes foundation failure, structural movement affecting load-bearing walls or roofs, major roof structure failure, and external wall systems that fail to keep water out. What is explicitly excluded is just as important to understand.
| Usually Covered in Years 3 to 10 | Usually Not Covered |
| Foundation movement and failure | Cosmetic defects and wear and tear |
| Structural wall or frame failure | Damage caused by your own alterations or additions |
| Major roof structure failure | Appliances, white goods, fixtures and fittings |
| External envelope failures causing damp penetration | Garden landscaping, paths, and driveways |
| Wall tie failure | Normal settlement cracks |
| Builder insolvency before completion (first owner only) | Damage caused by failure to maintain the property |
| Problems with utility services from external providers |
People regularly assume their structural warranty covers things it does not. A crack in plaster in year four is not a structural defect. A roof tile blown off in a storm is not a structural defect. If you are unsure whether your problem is covered, read your policy carefully before you contact the provider, because how you frame the claim matters.
Why You Cannot Sell Without One
If you build a new home without a structural warranty and then try to sell it within the first 10 years, you will almost certainly find that buyers cannot get a mortgage on it. Most high street lenders require a recognised structural warranty as a condition of lending on a new build property. Without one, the pool of potential buyers shrinks to cash buyers only.
Even cash buyers will expect a significant discount to reflect the absence of warranty protection and the additional legal risk. And their solicitor will flag it during conveyancing regardless. The problem does not go away.
Some lenders will accept a Professional Consultant’s Certificate (PCC) as an alternative to a structural warranty. A PCC is a document signed by a suitably qualified professional who has supervised the construction and is willing to certify that it was built to an appropriate standard. PCCs are accepted by some lenders but not all, and acceptance depends on the qualifications of the signatory and the lender’s specific criteria. Check UK Finance’s lender handbook for what individual lenders accept.
Get the warranty in place before you start building, not after. Retrospective warranties are difficult to obtain and expensive. Some providers will not issue them at all once a build is complete without full inspection records from during the construction process.
Who Are the Main Warranty Providers?
There are around a dozen providers operating in the UK market. Here are the main ones you are likely to encounter and what distinguishes them.
| Provider | Market Position | Notes |
| NHBC Buildmark | Covers approximately 80% of UK new builds | The most recognised name. Cover up to £1m per property. Builders must be NHBC registered. Most widely accepted by mortgage lenders. |
| LABC Warranty | 5 to 8% of market | Backed by Local Authority Building Control. Works alongside the local authority inspection process. Well regarded and lender-approved. |
| Premier Guarantee | Established provider | Part of a larger insurance group. Competitive on mid-sized developments. Lender-approved. |
| Checkmate | Growing market share | FCA-regulated. Covers a range of residential and mixed-use schemes. Accepted by the majority of mortgage lenders. |
| ICW (International Construction Warranties) | Specialist provider | Covers projects up to £50m in value. Accepted by 97% of mortgage lenders according to their published figures. |
| Build-Zone | Independent specialist | Covers residential, commercial, and mixed-use schemes. Backed by A-rated insurers. |
| Protek | Established provider | Offers 10 and 12-year warranties. Accepted by UK mortgage lenders. |
NHBC is the name most buyers recognise and the one most solicitors and lenders are comfortable with. But it is not the only valid option, and for smaller or more complex projects the alternative providers can offer comparable cover, often more quickly and sometimes at lower cost.
For a self-build or bespoke new build in London, NHBC requires the builder to be a registered NHBC member, which not all contractors are. If your contractor is not NHBC-registered, one of the alternative providers is the practical route.
What Does a Structural Warranty Cost?
The warranty is paid for by the builder or developer as part of the cost of the project, not directly by the homeowner at the point of purchase. But the cost is factored into the overall build cost, so it is worth understanding what the figure looks like.
For the NHBC Buildmark warranty, the developer typically pays between £1,500 and £3,500 depending on the size and value of the property. Larger, higher-value homes attract higher premiums. Alternative providers are sometimes cheaper, particularly for smaller schemes or self-builds, but premiums vary based on the project type, the contractor’s track record, and the insurer’s assessment of risk.
Set against the total cost of a new build in London, a structural warranty premium is a relatively small line item. Set against the cost of a major structural remediation without insurance, it is exceptional value. Foundation remediation, for example, can run to six figures on a London property. The warranty premium is not optional on any sensible risk basis.
Self-Build Warranties: What Are Your Options?
If you are commissioning a bespoke new build or managing your own self-build, the warranty landscape is slightly different because you are not buying from a developer who already has a warranty in place. You need to arrange it yourself.
Register with a provider early
Most warranty providers need to register the project before construction starts. They will carry out technical inspections at key stages during the build, similar to building control but focused on the warranty provider’s own technical standards. You cannot usually obtain a structural warranty retrospectively on a completed build without full inspection records, which is why early registration matters.
Your contractor’s registration status matters
NHBC requires the contractor to be a registered member. If your chosen contractor is not NHBC-registered, you will need to use an alternative provider. This is not necessarily a problem, but it is something to establish before you appoint the contractor, not after work has started.
Self-build specific policies
Several providers offer policies specifically designed for self-builds and bespoke commissions, including LABC Warranty, Build-Zone, and Protek. These are structured slightly differently from developer warranties but provide equivalent protection. Your mortgage lender will need to confirm they accept the specific provider before you commit.
Professional Consultant’s Certificate as an alternative
Some self-builders use a PCC instead of a structural warranty, where a suitably qualified architect or surveyor has supervised the construction throughout. PCCs are cheaper to obtain than a full warranty but are accepted by fewer lenders. If you plan to sell or remortgage within the first 10 years, check with your intended lender before relying on a PCC rather than a full warranty.
How to Make a Claim
The process differs depending on which period you are in.
In years 1 and 2
Report defects to your builder in writing. Keep a record of every item reported, the date it was reported, and the response you received. Most warranty providers have an online portal or defect reporting form for this period. If the builder does not respond within a reasonable timeframe or disputes the claim, escalate to the warranty provider’s resolution service.
In years 3 to 10
Contact the warranty provider directly. They will assess whether the problem qualifies as a structural defect under the policy terms. Be specific about what has failed and how. Provide photographs and any reports from independent surveyors if you have them. If the claim is rejected and you believe it should not have been, you can escalate to the Financial Ombudsman Service.
Document everything from day one
The strongest warranty claims are supported by good records. Keep your warranty policy document, the original build specification, any correspondence with your builder about defects, and inspection reports from during the construction period. If you have had to pay for independent surveys or temporary repairs while waiting for a claim to be resolved, keep those receipts too.
Do not carry out permanent repairs to a suspected structural defect before the warranty provider has inspected it. If you fix the problem before the inspection, the provider may argue there is no longer evidence of the defect and decline the claim.
Building in London and Need Advice on Warranties?
We build across all 33 London boroughs and manage the warranty process as part of every project. If you want to understand which warranty is right for your build, what your mortgage lender will accept, or how the process works from registration to completion, get in touch with our team.
DEVELOPER NOTES
Internal links: /blog/what-happens-if-your-builder-goes-bust, /contact
External links: NHBC Buildmark (nhbc.co.uk), UK Finance lender handbook (ukfinance.org.uk)
Suggested meta description: A structural warranty is a 10-year insurance policy on your new build. Here is what it actually covers, what it does not, which providers to know, what it costs, and why you cannot sell without one.
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Frequently Asked Questions
Is a structural warranty a legal requirement?
No, it is not a statutory legal requirement in the same way that building regulations approval is. But it is effectively mandatory in practice because most mortgage lenders require a recognised structural warranty before they will lend on a new build property. Without one, your buyers will struggle to get a mortgage, which significantly limits who can purchase the property and at what price. If you are planning to sell or remortgage within 10 years, a structural warranty is not optional in any practical sense.
Does a structural warranty cover all defects?
No. In years one and two it covers defects reported to the builder, who is obliged to put them right. From year three onwards it covers major structural defects only: foundation failure, structural wall or frame failure, major roof structure failure, and external envelope failures causing damp penetration. It does not cover cosmetic issues, wear and tear, damage from your own alterations, appliances, landscaping, or problems caused by failure to maintain the property. Read the policy exclusions carefully before assuming something is covered.
What happens if my builder goes bust during the defects period?
If your builder becomes insolvent during years one and two, the warranty provider steps in to cover the cost of remedying defects that the builder can no longer fix. This is one of the most important protections a structural warranty provides. Before completion, most policies also provide insolvency cover for deposits paid, typically up to 10% of the purchase price or £100,000, whichever is lower. Our guide on what happens if your builder goes bust covers this in more detail.
Can I get a structural warranty after the build is complete?
It is very difficult and sometimes impossible to obtain a retrospective structural warranty on a completed build. Most providers require registration before construction starts and carry out inspections at key stages during the build. Without those inspection records, there is no basis for the insurer to assess the risk. If you are considering buying a new build property that does not have a warranty, get specialist advice from a solicitor before proceeding.
How long does a structural warranty last?
The standard term is 10 years from the date of practical completion. Some providers offer 12-year policies. The warranty transfers automatically to new owners when the property is sold, so if you buy a new build that is three years old, you inherit the remaining seven years of cover. There is no way to extend or renew a warranty once it expires.
Do I need a structural warranty if I am self-building?
Yes, for the same reasons that apply to any new build. If you plan to sell or remortgage within 10 years, your buyers or lender will require one. The process is slightly different for self-builds because you need to arrange it yourself before construction starts rather than it being provided by a developer. Several providers offer self-build specific policies including LABC Warranty, Build-Zone, and Protek. Your contractor’s NHBC registration status will determine whether NHBC Buildmark is available to you.
