NHBC Buildmark Warranty: 2-Year Builder Period, 10-Year Structural Cover and Claims Process

Quick Answer: NHBC Buildmark is the UK's most widely used new-home warranty, covering a 2-year builder responsibility period (Part 2) followed by an 8-year structural-only period (Part 3), for a total 10 years from legal completion. The builder must register each plot with NHBC before construction; NHBC inspectors visit at defined stages. Structural claims in years 3–10 go directly to NHBC if the builder fails to remedy.

Summary

The NHBC (National House-Building Council) Buildmark warranty is held by more than 70% of newly built homes in the UK. It is not an insurance product in the conventional sense — it is a mixture of warranty obligations (builder's contractual duties) and insurance cover (NHBC's direct liability when the builder is no longer available or has failed to remedy a defect). Understanding the structure of the warranty is essential for builders, contractors, and tradespeople working on new-build sites, because the Buildmark warranty creates specific obligations that directly affect how work must be carried out and documented.

The NHBC Technical Standards (formerly called Chapter Standards) are the detailed specification against which all NHBC-registered builders must construct. These standards are referenced in the Buildmark policy — a failure to meet NHBC Technical Standards is a defect under the warranty. NHBC employs inspectors who carry out site inspections at defined stages; failing to give adequate notice for an inspection can result in work being uncovered, re-done, or excluded from warranty cover.

For subcontractors and specialist trades, the NHBC standards most likely to be directly relevant are Chapter 4 (foundations), Chapter 5 (floors), Chapter 6 (masonry), Chapter 7 (roofs), and Chapter 8 (internal works). Each chapter sets minimum standards that must be met or exceeded.

Key Facts

• NHBC Buildmark structure — three parts: Part 1 (pre-completion deposit protection), Part 2 (2-year builder period), Part 3 (8-year structural period); total cover 10 years
• Part 1 (Exchanged) — protects the buyer's deposit from the date of exchange of contracts to legal completion; covers builder insolvency
• Part 2 (Years 1–2) — builder responsibility period; all defects arising from failure to comply with NHBC Technical Standards are the builder's responsibility; NHBC mediates if the builder fails to remedy
• Part 3 (Years 3–10) — structural period; only covers physical damage to the load-bearing structure, waterproofing failures, and condensation; cosmetic, maintenance, and fair wear items are excluded
• NHBC registration fee — builders pay a per-unit registration fee at the start of the project; the fee varies by property value and type; around £700–£1,200 per unit for standard residential in 2025
• NHBC inspector stages — key inspection stages include: setting out, foundation excavation, foundation concrete, DPC, pre-plaster, roofing complete, drainage, and completion; some stages require advance notice
• NHBC Technical Standards — the detailed chapter standards (previously called NHBC Standards); Chapter 4 to Chapter 8 cover foundation to superstructure; Chapter 9 covers external environment
• Structural claim process — years 1–2: report to builder; builder has 8 weeks to remedy; years 3–10: report direct to NHBC; NHBC appoints investigator
• Exclusions — normal maintenance (redecorating, guttering, garden), cosmetic defects reported after 2 years, fair wear and tear, damage caused by occupier, subsidence where policy excess applies
• Zurich/Premier Guarantee — alternative new-home warranty providers; similar structure to NHBC but different coverage details and market share
• CE/UKCA marking — all products used on NHBC-registered homes must be CE or UKCA marked where applicable; NHBC inspectors can reject non-marked products
• Transfers on house sale — the Buildmark warranty transfers automatically to subsequent purchasers within the 10-year period; it is a document held with the property deeds
• NHBC Resolution Service — if the builder does not remedy a defect within the 2-year period, NHBC's Resolution Service manages the claim and can require the builder to act or take over the remediation

Quick Reference Table

Detailed Guidance

Registration and Pre-Construction Process

NHBC registration must be in place before construction begins. The process is:

1. Builder registration — the principal contractor registers with NHBC as a registered builder; NHBC assesses the builder's financial standing, track record, and technical capability
2. Site registration — each development site is registered; NHBC assigns a site inspector and sets out the inspection schedule
3. Plot registration — each individual plot is registered; the Buildmark policy is created at this stage; the buyer receives their policy documents at legal completion
4. Technical Standards compliance — the builder is contractually obligated to comply with NHBC Technical Standards throughout construction; departures must be agreed with the NHBC Technical Reviewer

NHBC Technical Reviewer: for large or complex sites, a pre-construction meeting with the NHBC Technical Reviewer is standard practice. The reviewer checks that the proposed construction method, details, and materials comply with NHBC Standards. Getting sign-off from the reviewer before construction avoids rejection of non-compliant work on site.

Key Chapter Standards for Trades

Chapter 4.2 — Ground floor construction Specifies minimum slab thickness, reinforcement, ground-bearing vs suspended design, and DPM specification. Key requirements: minimum 100mm concrete slab for ground-bearing floors; DPM lapped with cavity DPC; 150mm minimum clearance between floor level and external ground in sloping sites; polystyrene insulation to approved manufacturer details.

Chapter 5.1 — Suspended floors Covers both timber suspended and in-situ concrete suspended floors. Key for carpenters: minimum joist sizes from NHBC's own span tables (broadly aligned with Approved Document A but with additional restrictions); strutting requirements at mid-span; minimum clearance of 150mm between joist underside and subfloor void ground; moisture-resistant plasterboard for ceilings to suspended timber floors over garages.

Chapter 5.2 — Chipboard and plywood flooring Specifies minimum board thickness, tongue-and-groove application, gluing of T&G joints in wet areas, and required gaps at perimeter for expansion.

Chapter 6.1 — External masonry walls Minimum standards for brick and block work: mortar designation by exposure zone (BS EN 998-2); bed joint thickness 8–12mm; collar jointing and perpend alignment; wall tie type, spacing, and corrosion protection; cavity fill/insulation installation requirements; DPC position and installation; weep holes in cavity closers.

Chapter 7.2 — Roofing Covers both cut roofs and trussed rafter roofs. Critical for carpenters: NHBC inspectors will check truss bracing compliance; all bracing must be in place at inspection; any modification to trusses requires written approval from the truss designer with documentation on site; tile battens to BS 5534; underlay laps and fixed in accordance with the underlay manufacturer; ridge, hip, and verge details to NHBC standard.

Chapter 8.3 — Internal walls Stud walls must meet fire, acoustic, and structural criteria. Fire-stopping at all floor and ceiling junctions. Partitions adjacent to staircases to BS EN 1995-1-1 lateral load requirements.

NHBC Inspection Stages

NHBC inspectors visit at defined stages. The registered builder must give adequate notice before covering up work that will be inspected:

Failing to give notice before covering inspectable work can result in:

• The inspector requiring uncovering of the work
• The work being excluded from warranty cover
• A formal defect notice recorded against the plot
• In serious cases, a stop notice requiring all work to cease until the issue is resolved

Claims Process

Years 1–2 (Part 2 — Builder Responsibility Period):

1. Buyer reports defect to builder in writing
2. Builder has 8 weeks to inspect and provide a remedy
3. If builder fails to respond or remedy within 8 weeks, buyer contacts NHBC Resolution Service
4. NHBC Resolution Service appoints an inspector; investigates the claim; if the defect is a failure to comply with NHBC Standards, the builder is required to remedy
5. If the builder still fails to remedy (insolvency, refusal), NHBC takes over the remediation under the warranty insurance

Years 3–10 (Part 3 — Structural Period):

1. Buyer reports defect directly to NHBC Claims Service (not the builder)
2. NHBC appoints an investigator who assesses whether the defect constitutes physical damage to the load-bearing structure
3. If covered: NHBC manages and funds the remediation
4. If not covered (maintenance, cosmetic, fair wear): NHBC issues a reason for rejection

Policy excess: the Buildmark warranty has an excess (£500–£1,000 typically) that applies to Part 3 structural claims. Buyers should be aware of this when deciding whether to pursue a claim for borderline structural defects.

What Is and Is Not Covered

Covered under Part 3 (structural period):

• Physical damage to load-bearing elements (foundation movement, structural wall cracking, roof collapse)
• Waterproofing failures resulting in water ingress to the structure
• Condensation defects attributable to failure to comply with NHBC Standards (e.g., inadequate vapour barriers)

Not covered:

• Cosmetic defects (paint, tile chips, plaster hairline cracks) reported after the 2-year period
• Normal maintenance (guttering, pointing, window seal replacement)
• Fair wear and tear (door alignment drift, timber shrinkage)
• Damage caused by the occupier (DIY work, accidents, alterations)
• General settling of the building (small, non-structural)
• Damage caused by subsidence where the NHBC policy excess applies and the claim value is below excess

Alternative Warranty Providers

NHBC Buildmark is the dominant warranty product, but alternatives exist:

• Zurich Municipal New Home Warranty — similar 2+8 structure; accepted by most mortgage lenders
• Premier Guarantee — part of the MD Insurance Group; similar terms; used on some affordable housing schemes
• LABC Warranty — offered by Local Authority Building Control as an ancillary service; growing in uptake
• Q Assure Build Warranty — newer provider; less established; some lenders may not accept

For mortgage purposes, the warranty provider must be on the Council of Mortgage Lenders (CML) approved list. Always confirm with the buyer's solicitor and mortgage lender that the chosen warranty provider is acceptable before registering.

Frequently Asked Questions

Does the NHBC warranty cover extensions or conversions?

The standard Buildmark warranty applies to new builds only. For extensions and conversions, NHBC offers a separate Buildmark Solo product, which a registered builder can obtain for conversion or significant extension projects. The terms are broadly similar but the cover period may differ.

If I'm a subcontractor on an NHBC site, am I directly liable under the warranty?

The main (registered) builder is the party with direct NHBC obligations. However, as a subcontractor, you are liable to the main contractor under your subcontract for defects in your work. If a warranty claim arises from your work, the main contractor will seek to recover the cost from you. Ensure your contract includes appropriate defect liability periods and that your professional indemnity and public liability insurance covers warranty claims.

Can a warranty claim be made after a property is sold?

Yes — the Buildmark warranty transfers automatically with the property on any sale within the 10-year period. The new owner has the same rights as the original buyer. The warranty is a document held by the buyer/owner, not by the builder.

What products need CE or UKCA marking for NHBC sites?

NHBC requires CE or UKCA marking for any product used in a way that is regulated under the Construction Products Regulation (CPR). This includes structural steel, concrete blocks, roof tiles, insulation with a structural function, and many other products. From 1 July 2025, the UKCA mark replaced CE marking in Great Britain (England, Scotland, Wales). A 'period of grace' allowed CE-marked products to continue in use; confirm current requirements with NHBC's Technical Standards team.

How do I access NHBC Technical Standards?

NHBC Technical Standards are available to registered builders and their design teams via the NHBC website (nhbc.co.uk). Non-registered parties can purchase access to the standards documents. Key chapters relevant to tradespeople are freely summarised in NHBC Technical Guidance Notes available on the NHBC website.

Regulations & Standards

• NHBC Buildmark Warranty Policy — the contractual warranty document; conditions set the coverage and exclusions

• NHBC Technical Standards — the Chapter Standards that define compliance requirements for NHBC-registered construction

• Building Regulations 2010 — separate from NHBC; both apply simultaneously; NHBC Standards are generally more demanding than Building Regs minimum

• Consumer Code for Homebuilders — voluntary code adopted by most NHBC registered builders; consumer protection

• Housing Act 1974 (as amended) — establishes NHBC's statutory role in warranty provision

• BS EN 998-2 — masonry mortar requirements; referenced in NHBC Chapter 6.1

• NHBC: Buildmark Warranty — official warranty description and claims guidance

• NHBC: Technical Standards — access to chapter standards for registered builders

• NHBC: Resolution Service — claims process guidance

• Council of Mortgage Lenders: Warranty Schemes — approved warranty providers for mortgage purposes

• LABC Warranty — Local Authority Building Control warranty alternative

• part a structure — structural requirements aligned with NHBC Chapter 4–7

• roof trusses — NHBC Chapter 7.2 truss requirements

• planning vs building regs — how Building Regs and NHBC operate in parallel