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Property Insurance

Insurance Backed Guarantee UK — Structural Warranties and Latent Defects Insurance for Landlords

An insurance backed guarantee (IBG), also called a structural warranty or new home warranty, protects the owner of a new build or recently converted property against latent structural defects — defects hidden at completion that manifest later. Standard term: 10 years from practical completion. Two phases: (i) developer/builder's liability period (typically years 1–2) — the builder is primarily liable; the IBG insurer is the backstop if the builder fails to repair or is insolvent; (ii) insurer's liability period (typically years 3–10) — the IBG insurer is directly liable for the cost of repairing or rebuilding structural defects within the policy limits. Coverage includes: structural defects in foundations, floor, external walls, roof structure, frame; waterproofing and tanking failures; drainage defects causing structural damage. Excludes: fair wear and tear; cosmetic defects; consequential losses (loss of rent) unless specifically endorsed; owner's own modifications. Major providers: NHBC Buildmark (most widely recognised; NHBC-registered builders only; not for conversions; automatically passes to successive owners); Premier Guarantee (MD Insurance Services — available for new builds, conversions, refurbishments, self-build; accepted by most major lenders); Build-Zone; ProWarranty; Checkmate. Lender requirements: mortgage lenders require an IBG from an approved provider for new build properties; most require 8+ years remaining at mortgage offer date. Assignment on sale: most modern IBGs (NHBC Buildmark, Premier Guarantee) automatically pass to the buyer for the remainder of the term without formal assignment; some older personal policies require formal assignment with insurer consent. Claims: document defect with photographs; obtain structural engineer's report; notify insurer promptly in writing; insurer appoints loss adjuster; professional evidence of latent construction defect essential. Scotland: NHBC Buildmark, Premier Guarantee, and other approved providers accepted by Scottish lenders.

10 min readUpdated 7 June 2026Last reviewed: 17 May 2026insurance-backed-guaranteestructural-warranty-landlordnhbc-buildmarkpremier-guarantee-warranty

IBG Coverage, Major Providers, and Lender Requirements

Insurance backed guarantee structure: (i) developer/builder's liability period (years 1–2) — builder primarily liable; IBG insurer = backstop if builder fails or becomes insolvent; (ii) insurer's liability period (years 3–10) — IBG insurer directly liable for structural defect remediation within policy limits. Coverage: structural defects in foundations, floor, external walls, roof, frame; waterproofing/tanking failures; drainage defects causing structural damage. Excludes: fair wear and tear; cosmetic defects (minor cracks, plasterwork); consequential losses (loss of rent) unless endorsed; owner's own modifications or alterations. Major providers: NHBC Buildmark — most widely recognised; NHBC-registered builders only; NOT available for conversions; accepted by virtually all UK mortgage lenders; automatically passes to successive owners (registered against the property, not personal to the developer); Premier Guarantee (MD Insurance Services) — available for new builds, conversions, refurbishments, self-build; accepted by most major lenders; Build-Zone — conversions, new builds, commercial-to-residential; ProWarranty — new builds, conversions, basement conversions, extensions; Checkmate (Warranty Group) — structural warranties and latent defects insurance. Lender requirements: UK Finance / CML Handbook sets out approved warranty schemes for residential mortgage purposes; most lenders require 8+ years remaining at the date of the mortgage offer; a property without an approved IBG may be unmortgageable. Scotland: NHBC Buildmark and Premier Guarantee accepted by Scottish lenders; Scottish Building Standards (Building (Scotland) Act 2003) compliance is a separate regulatory requirement.

Assignment on Sale and Making an IBG Claim

Assignment on sale: NHBC Buildmark — automatically passes to successive owners for the remainder of the 10-year term without any formal assignment; the buyer receives the full remaining warranty benefit at completion; Premier Guarantee and most modern IBGs — drafted to benefit 'the owner for the time being'; automatically pass to the buyer on completion; verify by reading the policy transfer provisions; older personal policies — some older IBGs were personal to the original developer and require formal assignment with insurer consent; the seller's solicitor handles the assignment as part of conveyancing; on purchase, register the warranty in the buyer's name with the provider to ensure direct claim access. Due diligence checklist for buyers: obtain copy of IBG policy document, warranty certificate, and policy number; check unexpired term (how many years remain); verify whether policy automatically passes to buyer; check for any previous claims (material to coverage and limits); confirm with lender that remaining warranty term meets their requirements. Claims process: document the defect promptly with date-stamped photographs; obtain a structural engineer's or chartered surveyor's report identifying the defect as a latent construction defect (not wear and tear or the owner's modifications); notify the warranty provider promptly in writing (with evidence); in years 1–2, notify the developer/builder first (keep written records of all builder communications); in years 3–10, notify the IBG insurer directly — they appoint a loss adjuster; the insurer is liable for remediation costs within policy limits; professional evidence is essential for a successful claim.

Frequently asked questions

What is an insurance backed guarantee for a new build property?+

An IBG (also called a structural warranty or new home warranty) is an insurance policy that protects the owner against latent structural defects — defects hidden at completion that manifest later. The standard term is 10 years from practical completion. The most widely recognised IBG is the NHBC Buildmark warranty.

Does an NHBC Buildmark warranty transfer to the buyer on sale?+

Yes — the NHBC Buildmark warranty automatically passes to successive owners for the remainder of the 10-year term. It is registered against the property, not personal to the developer, so the buyer receives the full remaining warranty benefit at completion without any formal assignment.

Do I need an IBG to get a buy-to-let mortgage on a new build?+

Yes — mortgage lenders almost universally require a structural warranty from an approved provider for new build properties. Most lenders require at least 8 years of the warranty term to remain at the date of the mortgage offer. A property without an accepted IBG may be unmortgageable.

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