NHBC Buildmark: the ten-year warranty on new homes

A building warranty covers major problems with newly built or converted homes, and NHBC Buildmark is among the best known of them. It runs for ten years from completion and is split into three main parts: cover before the building is completed, cover for years 0 to 2, and cover for years 3 to 10¹. The builder buys it before construction starts, but it protects the homeowner, not the builder².

That structure matters more than the headline length. In the first two years the builder is expected to put defects right, and the insurer usually acts as mediator through a resolution or conciliation service¹. From year three the warranty turns into insurance against structural problems where the builder has not complied with technical requirements¹.

Most mortgage lenders will not lend on a new build without a warranty from an approved scheme. Principality asks for an NHBC or similar ten year new build warranty on homes built with modern methods of construction³, and Cambridge Building Society accepts NHBC, LABC, Premier Guarantee, BLP, Build Zone, Checkmate (Castle 10), CRL and existing Zurich policies on homes built or converted in the past ten years⁴.

What NHBC Buildmark covers on a new home

Buildmark is a structural warranty, and the cover is defined by what has gone wrong rather than by a list of parts of the house. In years 3 to 10 you are covered for structural problems where the builder has not complied with technical requirements¹. Where the insurer also carried out building control or building regulations inspections, there is extra cover for health and safety issues and contaminated land¹.

The warranty is one of a group of schemes lenders recognise. Newcastle Building Society's acceptable list runs to NHBC, Build-Zone, LABC, Zurich Municipal, HAPM, Premier Guarantee, BLP, Protek, AHCI Advantage, ICW, Checkmate Castle 10, Checkmate Knight 10, Aedis Homeproof New Build 10 Residential Warranty, Aedis Homeproof New Build 10 Residential Warranty for Self Build, and a Professional Consultants Certificate⁶. Cambridge Building Society's list is shorter but overlaps on the main names⁴. The practical point for a buyer is that the warranty is not optional decoration: without one from an accepted scheme, a mortgage may not be available at all.

Warranties also sit alongside the consumer codes that govern how a new home is sold. A new home built by a developer registered with Premier Guarantee and covered by a New Homes Warranty will be covered by the Consumer Code for Home Builders and the New Homes Quality Code⁷. Those codes deal with the buying process and after-sales service, while the warranty deals with the building itself.

Self-builders face the same question from the other side. Official guidance for building your own home says it is important to have the right insurance and warranty cover to protect you against some of the risk if things go wrong⁸. A structural warranty is bought by the builder before construction starts, which for a self-build means you are both the buyer and the beneficiary².

Buildmark runs in stages: builder insolvency cover, builder warranty and insurance

The three stages do different jobs, and knowing which one you are in tells you who to contact.

Before completion. You are covered if the builder is insolvent or commits fraud and does not complete the build. The insurer should refund your money, part-refund it, or arrange for the building to be finished¹. This is the stage that protects a deposit and any stage payments already made.

Years 0 to 2. The builder must sort out problems in the first two years after the building is complete, and the insurer usually acts as mediator through a resolution or conciliation service¹. This is a builder warranty rather than an insurance policy in the ordinary sense: the obligation sits with the builder first.

Years 3 to 10. The cover becomes insurance against structural problems where the builder has not complied with technical requirements¹. Claims here are subject to the £1,000 minimum and the index-linked threshold¹.

Builder warranty or insurance: who fixes what, and when

The split between the builder's obligation and the insurer's is the part buyers most often get wrong. In the first two years the warranty means the builder must sort out problems, and the insurer's role is usually mediation through a resolution or conciliation service rather than sending out its own contractor¹. Reporting defects in that window is the buyer's job: it is up to you to report defects within the first two years⁹.

From year three the position reverses. The builder is no longer on the hook under the warranty, and a claim becomes a claim against the insurer. For a claim to be valid, normally all of the following must be true: the home has a defect, the builder has breached technical requirements, and the defect has caused damage¹. All three, not one or two.

That combination is why a defect that is annoying but not structural, or a structural issue that does not trace back to a breach of technical requirements, can fall outside the cover. The £1,000 minimum does the rest of the filtering: small repairs are a matter for the builder in the first two years and for the owner afterwards¹.

Where the insurer carried out building control or building regulations inspections, the extra cover for health and safety issues and contaminated land sits on top of the standard structural cover¹. Not every policy will have it, because it depends on who did the inspections.

Flats and maisonettes: cover for shared parts of the building

A warranty on a flat covers the home, but the building around it is a separate question. Multiple-occupancy building insurance policies cover houses that have been divided into flats, blocks of flats, and estates with a mix of buildings and houses¹⁰. If you live in a block of flats, the building may already be insured and your contribution covered by your service charge¹¹.

For shared owners, the lease makes the shared owner the homeowner, responsible for all the repairs and maintenance in their home, including major structural works and major repairs¹². Where the problem is in a shared part of the building, the cost is divided between you and the other flat owners if the reserve fund does not cover it⁵. That is a service charge question as much as a warranty question, and it is worth knowing which of the two applies before work starts.

Buying a home that already has Buildmark

The warranty runs with the home, not with the person who bought it new. If you buy a home through a shared ownership resale, any remaining period on the building warranty will transfer to you⁵. The same principle applies to an ordinary resale of a home still inside its ten years: what is left of the cover comes with the property.

That makes the paperwork part of the purchase. Ask for the warranty certificate and the policy document, and check how many years remain and which stage the home is in. A home in year eight has a very different proposition attached to it from one in year one, because the builder's two-year obligation has long expired and only the insurer's structural cover remains¹.

If you are buying through the Open Market Shared Equity scheme in Scotland, the seller will give you a Home Report before you buy¹³. That is a survey document rather than a warranty, and it does not replace one.

How to make a Buildmark claim

The route depends on the stage. In the first two years, report the defect to the builder in writing and keep a record of every contact. The warranty says the builder must sort out problems in that window, and the insurer usually acts as mediator through a resolution or conciliation service¹. If the builder does not respond, the mediation route is the next step rather than a claim.

From year three, the claim goes to the insurer, and it needs to show a defect, a breach of technical requirements and damage caused by that breach¹. Photographs, dates, correspondence and any reports from a surveyor or engineer all help establish those three elements.

If the builder is insolvent or commits fraud and does not complete the build, the claim is made under the pre-completion stage, and the insurer should refund money, part-refund it, or arrange for the building to be finished¹. That is a different process from a defects claim and should be raised as soon as the position is known.

Where Buildmark does not pay out

The exclusions follow from how the cover is defined. A repair costing less than £1,000 is not paid, and the threshold is index-linked¹. A defect that does not involve a breach of technical requirements is outside the years 3 to 10 cover, as is a defect that has not caused damage¹. In the first two years the obligation is the builder's, so a buyer who never reports a defect to the builder has not started the process the warranty assumes¹.

There is also the question of what a warranty is not. It is not buildings insurance, which covers the building itself and the contents inside your home against events such as fire and flood¹⁴. It is not a substitute for a survey, and it does not cover the general wear and tear that any home accumulates. Buildings insurance is based on rebuild cost, not market value, which is a separate calculation from anything in a warranty¹⁵.

For leaseholders, the block policy and the service charge sit alongside the warranty, and the two can overlap in confusing ways. If the problem is in a shared part of the building, the cost is divided between the flat owners if the reserve fund does not cover it⁵.

If you disagree with NHBC's decision

Building warranty complaints go to the Financial Ombudsman Service, but there is a gate to pass first. The ombudsman can only look at complaints after the insurer has written a resolution or conciliation report, that report told the builder to do something by a deadline, and the builder failed to complete the works by the deadline or is insolvent or not co-operating¹. In other words, the mediation stage has to have run its course.

Once a complaint is accepted, the ombudsman has real powers. It may ask the insurer to deal with a claim they have rejected, take over from the builder if the builder is insolvent, add interest, pay for more work, or pay compensation for loss or inconvenience¹.

The usual complaint timetable applies to the insurer as it does elsewhere in financial services. A bank or building society must investigate a complaint and give a clear answer within eight weeks¹⁶, and you must give your bank or building society at least eight weeks to sort the problem out unless they send a letter of deadlock earlier¹⁷. Mortgage complaints follow the same shape: complain to the lender or intermediary first, who should reply within eight weeks, and if you are unsatisfied or get no reply in that time, take it to the ombudsman¹⁸.

NHBC publishes its own complaints data. For the period 1 April 2025 to 30 September 2025 it reports 745 complaints opened, 772 closed, 44% upheld, with product performance and features the main cause¹⁹.