Modular Construction Insurance UK Specialist Broker: Our Complete Guide 2026
Why Modular Construction Needs Specialist Insurance
Modular and offsite construction — the family of Modern Methods of Construction (MMC) that includes volumetric modular, panellised systems, pods, hybrid and 2D/3D prefabricated assemblies — has become one of the most operationally and financially complex parts of the UK building sector. The industry now turns over an estimated £15.9 billion annually and is growing at around 4.2% per year, yet it is also the segment where insurer appetite has tightened the most, where insolvencies have hit hardest, and where standard construction insurance wordings are most likely to leave dangerous gaps.
The reasons sit at the intersection of three things. First, MMC moves the highest-value, most complex part of construction into a controlled factory environment — which is good for quality, but concentrates risk into a small number of expensive locations where a single fire can wipe out an entire production batch and several live projects at once. Second, the modules then have to travel — by road, sometimes by sea — to site, in lifts that present some of the highest-severity loss scenarios in the construction sector. And third, once on site, modules are assembled in days, not months, which dramatically compresses the installation window and creates fire, water, and snagging exposures that conventional contract works wordings were never designed to absorb.
Layered on top of all that is the financial reality the sector lived through between 2022 and 2025. Ilke Homes, House by Urban Splash, Caledonian Modular, Modulous, Mid Group, L&G Modular Homes, TopHat, Connect Modular, Jans Offsite Solutions, Elements Europe, and Kingston Modular all collapsed or wound down in the space of three years — and that wave of insolvency materially changed how insurers underwrite this risk. RICS noted in 2026 that damage to prefabricated modular units may be more expensive to repair in situ than the original off-site construction cost, and the wave of insolvency in modular manufacturing makes the ability to replace damaged items even more uncertain.
This guide is written for the businesses operating in that environment — modular manufacturers, MMC contractors, developers using offsite, and the buyers of finished modular buildings. It addresses each exposure specifically, with two interactive tools to help you scope the right programme for your position.
1. The Specific Risk Profile of Modular and Offsite Construction
Why MMC Doesn't Fit Standard Construction Wordings
Conventional contractors all risks (CAR) insurance was designed for a build that happens almost entirely on site, in sequence, over many months. The risk picture changes gradually as the project progresses, and damage is largely confined to whatever is physically on the site at the time of the loss. Modular construction inverts that model. Value is concentrated off site in a factory, then in transit, then on site only briefly during installation. A single fire, theft, water damage event, or transit incident can destroy bespoke components that take months to remanufacture — and those components are usually project-specific, so the loss isn't just the value of the modules, it's the value plus the consequential delay.
Specifically, modular and offsite construction creates these exposures that conventional CAR wordings often handle poorly:
- Stock and work-in-progress sitting in the manufacturer's factory before despatch — frequently a higher accumulated value than the site itself holds at any one time
- Bespoke, project-specific components with long replacement lead times — meaning physical damage rapidly turns into Delay in Start-Up (DSU) and advance loss of profits exposure
- Multi-stage transit — by road or sea — with handling at the factory loading bay, transfer to road haulage, possible storage at a marshalling yard, and final lift onto the site
- Crane lifts of high-value modules — sometimes weighing 20+ tonnes per pod, with the loss severity in a single drop event approaching the value of an entire factory's monthly output
- Partially completed structures on site that may consist of stacked modules without the weatherproofing, fire suppression, or load-path completion that a conventional traditionally-built frame would have at the same point
- Product-liability-style exposure on the manufacturer where modules later prove defective in service — an exposure that bridges professional indemnity, product liability, and latent defects insurance
The Concentration Problem
A traditional housebuilder spreads its in-progress value across dozens of plots. A modular manufacturer concentrates it into a single factory and a handful of marshalling yards. Insurers consistently flag fire as the clearest differentiator in MMC because losses can occur before completion and can affect stock, modules, storage sites, transport staging and unfinished structures all at once. That single-location concentration is one of the reasons standard combined commercial property policies often decline to write modular manufacturing risk on standard terms, and why specialist market placement is increasingly the only viable route for serious factory exposures.
Your Position in the MMC Supply Chain Determines Your Liability
Where you sit in the modular supply chain changes the shape of your exposure significantly. Under standard UK construction law and the contractual frameworks typically used (JCT, NEC, bespoke developer contracts), liability flows differently depending on whether you are:
- The modular manufacturer — primary product and workmanship liability for the modules themselves, plus factory property and BI exposure
- The MMC main contractor — responsible for the integrated build, including coordinating the modules into the wider structure; full contractor liability for site works, plus interface risk where modules meet traditional construction
- The developer using MMC — overall project risk, funding exposure if the manufacturer fails mid-project, and warranty/sales liability to the eventual occupier or purchaser
- An installer or specialist sub-contractor — installation workmanship, lifting and handling liability, and interface defects at the connection points
- A logistics or transit specialist — goods-in-transit liability for high-value modules during road or marine movement
2. Core Covers Every Modular Construction Business Needs
Contractors All Risks (CAR) — Specifically Worded for MMC
The base policy for any construction project, but one that requires careful negotiation for MMC. A standard CAR wording typically attaches when materials arrive on site. For modular construction, that wording is inadequate — significant value sits in the factory and in transit long before any site delivery. The policy must explicitly extend to off-site storage, work in progress at the manufacturer's premises, multi-stage transit, and lifting operations. Sum insured must reflect not just the contract value but the bespoke remanufacture cost of any individual module, which can exceed the original production cost where the manufacturer is dealing with a one-off replacement rather than a production run.
Professional Indemnity — Including Design Responsibility
For modular manufacturers and MMC contractors, professional indemnity insurance is critical because modular construction blurs the traditional separation between design and build. Where the manufacturer designs the module system as well as building it, PI must cover both — including the consequence of design errors that only become apparent after installation, sometimes years later. PI is also the cover that responds where structural or fire defects in modular elements are alleged to result from design or specification failures rather than pure workmanship.
Product Liability
Modular components are products as well as construction elements. If a module — or a panellised system, or a structural insulated panel — fails in service in a way that causes injury or property damage, the claim is brought under product liability principles. This is particularly relevant for manufacturers selling standardised module products into multiple projects, where the same defect could simultaneously affect dozens of buildings. Confirm with your broker that product liability is explicitly included and that the limit reflects the multi-project aggregation risk, not just the worst case for a single building.
Public Liability
Both factory operations and on-site installation create public liability exposures. Factory visitors, deliveries, and any third-party access to the manufacturing premises sit within standard PL. On site, the installation phase — particularly crane lifts of large modules — creates significant public liability exposure to neighbouring properties and the public. Minimum £5 million for factory operations, with higher limits considered where lifts pass over public highways or adjacent occupied buildings.
Goods in Transit and Marine Cargo
Standard motor or goods-in-transit policies are typically inadequate for high-value modular components. A bespoke marine cargo or specialist transit policy is usually required, covering the module from loading at the factory through to final placement on the site foundations. Coverage must include loading and unloading operations — the points at which most transit losses actually occur — and storage in transit at any marshalling yards.
Property and Business Interruption — Factory Cover
For modular manufacturers, factory property insurance is the largest single line on the programme after CAR. The buildings, plant, fitted machinery, stock, and work-in-progress all need to be insured at full reinstatement value, with realistic indemnity periods for business interruption. Eighteen to twenty-four months minimum is now considered standard for modular manufacturing BI cover, reflecting the time to source replacement specialist plant, secure new accreditations, and rebuild client confidence post-loss.
Latent Defects / Structural Warranty
For modular residential and commercial development, structural warranty providers — NHBC, LABC Warranty, Premier Guarantee, Build-Zone, and Checkmate — are increasingly cautious about non-traditional construction. Some require additional technical review of the manufacturing system, others apply premium loadings, and a small number decline modular systems they have not pre-approved. Securing structural warranty cover at the planning stage rather than at completion is essential — and is also typically a condition of mortgage lending on the finished units.
Employers' Liability
Legally required under the Employers' Liability (Compulsory Insurance) Act 1969 for any business with employees. Minimum £5 million. For modular manufacturers, EL is a meaningful exposure: factory environments combine repetitive heavy lifting, overhead crane operations, machinery use, and timber dust or composite material handling — all known sources of injury claims. The HSE prosecution of Ilke Homes for lifting equipment regulations breaches is a reminder that factory MMC operations are subject to the same — and sometimes more stringent — health and safety enforcement as conventional sites.
Cyber Insurance
Modular factories are heavily digitised. BIM models, CNC programs for CAM machining, design IP, ERP systems controlling production scheduling, and increasingly IoT-connected production lines — a cyber event taking out any of these halts production immediately. Construction cyber insurance covers ransomware response, system restoration, and the business interruption flowing from a cyber-caused production stoppage. For modular, where production scheduling is the bottleneck, the BI element is often more material than the breach response itself.
3. Business Type Cover Checker
Select your primary business model for a tailored cover checklist.
Modular Construction Business Cover Checker
Select your business type to see the recommended insurance programme
Volumetric Modular Manufacturer (Category 1)
- LEGAL Employers' Liability — minimum £5m; factory environments combine machinery, overhead lifting, and dust/composite exposures; include all production, design, and logistics staff
- CRITICAL Specialist factory property and BI — single-site concentration risk requires specialist underwriting; minimum 18–24 months BI indemnity period to allow for plant replacement and accreditation reinstatement
- ESSENTIAL Stock and work-in-progress — module values can exceed factory plant values at peak production; insure at full remanufacture cost, not original production cost
- ESSENTIAL Product Liability — modules are products; aggregate exposure across multiple projects must be reflected in the limit; minimum £10m for serious manufacturers
- ESSENTIAL Professional Indemnity — design responsibility for the module system itself; minimum £5m; confirm cover for design errors discovered post-installation
- ESSENTIAL Marine cargo / specialist transit — bespoke high-value transit cover from factory loading bay through to site placement; standard GIT inadequate
- ESSENTIAL Public Liability — factory visitors, deliveries, factory tours; minimum £5m
- ESSENTIAL Cyber Insurance — BIM, CNC, ERP and production-control systems are all single points of failure; BI from cyber-caused production stoppage is the primary exposure
- RECOMMENDED Equipment breakdown for production-critical machinery — CNC routers, presses, and overhead cranes have long replacement lead times
- RECOMMENDED Trade credit insurance — given the recent wave of developer insolvency, debtor protection is a serious consideration for the manufacturer side too
Panellised / SIPs / Timber Frame Manufacturer
- LEGAL Employers' Liability — minimum £5m; timber handling, glue and adhesive use, and saw operations are the main injury risks
- CRITICAL Factory fire — timber and composite panel manufacturers face significantly higher fire premiums; sprinkler systems, hot work permit procedures, and dust extraction directly affect premium
- ESSENTIAL Property and BI — minimum 18 months indemnity; timber/composite production lines are not easily replaced from stock; specialist machinery has lead times
- ESSENTIAL Stock and WIP — particularly relevant for SIPs and CLT producers where finished panel inventory can be substantial
- ESSENTIAL Product Liability — panel systems must perform structurally for the design life; defects can affect multiple buildings simultaneously
- ESSENTIAL Professional Indemnity — particularly where the panel manufacturer also provides the structural calculations or BIM-coordinated design package
- ESSENTIAL Goods in transit — panels are bulky, weather-sensitive, and easily damaged in handling; specialist GIT or marine cargo wording
- RECOMMENDED Latent defects participation — where you supply systems used in structural warranty-covered developments, your supply position may attract loadings if not pre-approved by the warranty provider
- CONSIDER Fire risk surveyor engagement — for higher-risk premises, having a recent specialist fire risk assessment significantly affects premiums
MMC Main Contractor
- LEGAL Employers' Liability — minimum £5m; site-based labour plus office and design staff
- ESSENTIAL Contractors All Risks — explicitly extended to cover off-site storage, work in progress at the manufacturer's premises, multi-stage transit, and lifting; standard wordings will leave material gaps
- ESSENTIAL Public Liability — minimum £5–10m; crane lifts over public highways or adjacent buildings may require higher limits
- ESSENTIAL Professional Indemnity — where the contractor takes design responsibility for the integration of modules into the wider structure; interface design is the highest PI exposure in MMC
- ESSENTIAL JCT/NEC contract works wording review — many standard CAR policies were drafted for traditional builds; specifically request MMC-suitable wording extensions
- RECOMMENDED Delay in Start-Up (DSU) / Advanced Loss of Profits — given module replacement lead times, DSU is a particularly relevant cover for MMC contractors
- RECOMMENDED Sub-contractor due diligence — confirm manufacturer's PI, product liability, and financial standing before signing; manufacturer insolvency mid-project is now a known industry risk
- CONSIDER Cyber — increasingly relevant where the project relies on shared BIM models and digital coordination across the supply chain
Developer Using MMC for Residential or Commercial
- LEGAL Employers' Liability — for any directly employed staff; minimum £5m
- CRITICAL Developer-arranged CAR — increasingly the preferred structure for MMC schemes; gives the developer control over the wording, limits, and breadth of cover, including off-site exposures
- ESSENTIAL Latent Defects / Structural Warranty — confirm warranty acceptability of the MMC system before contract; obtain provider's written approval of the manufacturer and system specification
- ESSENTIAL Public Liability — minimum £5m; site PL plus any sales suite or show home exposure
- ESSENTIAL Professional Indemnity — where the developer takes design coordination responsibility under the contract; minimum £5m for residential schemes
- ESSENTIAL Manufacturer financial standing review — credit-check and review accounts of any modular supplier before placing significant orders; the 2022–25 wave of insolvencies has changed lender and insurer expectations
- RECOMMENDED Performance bonds and parent company guarantees — replace some of the role insurance plays for traditional contractors; standard in major MMC schemes
- RECOMMENDED Decennial / Inherent Defects Insurance — for commercial schemes; offers no-fault structural cover for 10–12 years post-completion
- CONSIDER Building Safety Act compliance review — for higher-risk buildings (18m+), gateway approval requirements directly affect insurability and saleability
Specialist Installer / Sub-Contractor
- LEGAL Employers' Liability — minimum £5m; high-risk activities including working at height and crane assistance
- ESSENTIAL Public Liability — minimum £5m; lifting and craning operations create significant third-party exposure
- ESSENTIAL Contractors All Risks (installer level) — for any plant, tools, hired-in lifting equipment, and your specific scope of works
- ESSENTIAL Professional Indemnity — even pure installation contracts can carry design risk where the installer is responsible for setting out, levelling, or final tolerances at module connections
- ESSENTIAL Hired-in plant and crane insurance — confirm that hired cranes are covered for hook-load damage as well as physical damage to the crane itself
- RECOMMENDED Tools and equipment — including specialist lifting accessories, spreader beams, and bespoke rigging
- CONSIDER Working at height risk assessment — major insurers increasingly require evidence of method statements and competence records for height work
Bathroom / Kitchen Pod or Fitout Module Specialist
- LEGAL Employers' Liability — minimum £5m; factory plus install staff
- ESSENTIAL Factory property and BI — pod production is typically lower fire load than CLT/timber but services (plumbing, electrical) make water damage a major exposure
- ESSENTIAL Stock / WIP — pods are high-value finished units; aggregate stored value can be substantial at peak production
- ESSENTIAL Product Liability — pods are products; plumbing and electrical defects creating water or fire damage in occupied buildings are the principal exposure
- ESSENTIAL Professional Indemnity — services design, regulatory compliance (Part G/L), and pod-to-building interface design
- ESSENTIAL Goods in transit — pods are bulky, sensitive to damage at corners and during craning; specialist cargo wording
- RECOMMENDED Hot and cold testing protocols — documented pre-despatch test records reduce both claim frequency and premium
- CONSIDER Latent water damage cover — where pod plumbing defects emerge post-handover, the building damage caused can far exceed the pod value
4. Project Risk Assessor
Select your construction system and your position on the project to get a specific risk rating and the insurance implications for your business.
MMC Project Risk Assessor
Select your construction system and project role to see your specific risk profile
5. The Fire Risk Problem in MMC
Fire is the single most material exposure in modular and offsite construction, and it is the area where insurance pricing has hardened most sharply over the past three years. The reason is structural to how MMC works: losses can occur before completion and can affect stock, modules, storage sites, transport staging and unfinished structures all at once — a profile that doesn't exist in conventional construction, where the value is more thinly spread across a long build programme.
Where the Fire Risk Sits
Modular and offsite construction concentrates flammable load in three places that conventional construction simply does not have:
- The factory itself — finished and part-finished modules, raw timber, EPS/SIPs insulation, packaging materials, paint and adhesive stocks, often all under one roof. A typical CLT or timber-frame factory can hold three to six weeks of forward production at any one time, representing significant aggregate value
- The marshalling yard — modules awaiting despatch to site, sometimes including project-complete sets that cannot be reproduced quickly if destroyed. Marshalling yards rarely have factory-grade fire suppression and are often forgotten in fire risk reviews
- The partially-completed building on site — particularly between module placement and the installation of the final fire compartmentation, fire stopping, and protective finishes. MMC builds can sit at this exposed stage for weeks or months as fit-out completes
Why Standard Fire Underwriting Doesn't Translate
A conventional commercial property insurer assesses fire risk based on the building, its occupancy, its sprinkler and detection systems, and the surrounding fire load. That framework was developed for static occupancy. A modular factory has a constantly shifting fire load: stock comes in, products go out, work-in-progress moves through the factory in days or weeks. The peak fire load in a modular factory is significantly higher than the average, and standard underwriting based on average occupancy understates the risk.
The result, since 2023, has been:
- Several mainstream commercial insurers withdrawing from MMC factory risk altogether
- Significant deductible increases — construction deductibles as high as £150k are now common
- Specialist market placement through Lloyd's syndicates and specialist MGAs becoming the standard route for serious modular manufacturers
- Insurers requiring formal fire risk surveys (typically RC1-level commercial fire surveys) before quoting
- Increased scrutiny of sprinkler systems, hot work permit procedures, dust extraction, and waste management
The Site-Stage Fire Risk Specific to MMC
On site, MMC creates a fire exposure window that traditional construction doesn't. With volumetric modular, the structural frame, services first fix, and internal finishes typically arrive complete in the module — but the fire compartmentation between modules, the fire stopping at floor and wall junctions, and the external fire-rated cladding system are all completed on site. Between module placement and final fire-stopping completion, you can have a multi-storey structure with limited compartmentation and significant combustible content — a fire that would have been contained in a single module post-completion can spread vertically and horizontally in a way that wouldn't happen in either a completed building or a traditional in-progress build.
The Joint Code of Practice on Fire Prevention on Construction Sites (JCoP) was updated in 2022 to address timber and MMC-specific risks. Compliance with JCoP — including hot work controls, smoking restrictions, materials storage standards, and fire detection during the build — is increasingly a CAR policy condition, not just good practice.
6. Transit and Lifting — The Highest-Severity Stage
For any modular project, the transit and lift sequence is the single highest-severity loss exposure on a per-event basis. A single drop during a crane lift can destroy a module that took weeks to manufacture and cannot be replaced quickly. A road traffic incident with a low-loader carrying a full-volume module can destroy the unit, damage public infrastructure, and create third-party injury liability all at once.
The Transit Liability Picture
| Stage | Primary Risk | Typical Cover Source |
|---|---|---|
| Factory loading bay | Damage during loading; rigging or lifting equipment failure | Factory PL / specialist transit at attachment |
| Road transit | RTA, route damage (bridge strikes, overhead line strikes), theft | Specialist GIT or marine cargo; carrier's haulier insurance secondary |
| Marshalling yard / storage | Fire, theft, weather damage, vandalism, third-party impact | Off-site storage extension under CAR; specialist standalone if yard is third-party owned |
| Site delivery and offload | Damage during offload, crane positioning, traffic management | Site PL / CAR off-site cover |
| Crane lift to final position | Drop, swing damage, overload, third-party impact (overhead lines, adjacent buildings) | Hired-in plant + lifting operations cover under CAR; PL for third-party |
| Module-to-module connection | Damage during alignment, weather ingress before sealing, theft of completed modules | CAR (post-installation), works in progress |
The Lifting Operations Issue
Lifting operations on MMC sites are governed by the Lifting Operations and Lifting Equipment Regulations 1998 (LOLER) and the related Provision and Use of Work Equipment Regulations 1998 (PUWER). For module placement, that means: lift plans signed by an Appointed Person, suitable spreader beams and slings, ground-condition assessments for the crane, and exclusion zones for personnel during the lift. From an insurance standpoint:
- Insurers increasingly require sight of the lift plan and Appointed Person's certification before the lift
- Hired-in cranes must be insured for the hook-load value as well as physical damage to the crane
- The interface between the crane company's insurance, the installer's PL, and the main contractor's CAR is where coverage disputes typically arise after a lift loss — clarify the indemnification chain before mobilisation
- The 2025 HSE prosecution of Ilke Homes over factory lifting operations — alleging that floor cassette lifts via overhead crane were inadequately planned and supervised — is a reminder that LOLER applies in the factory as much as on site, and breaches generate criminal as well as civil exposure
7. Manufacturer Insolvency and Supply Chain Collapse
The 2022 to 2025 period has been brutal for UK modular manufacturers. The list of major failures and wind-downs is now substantial: Ilke Homes, Modulous, Mid Group, Eco Modular Buildings, Caledonian Modular, L&G Modular Homes, Urban Splash House, TopHat, Connect Modular, Jans Offsite Solutions, Elements Europe, and Kingston Modular have all entered administration, liquidation, or controlled wind-down within three years. Ilke Homes alone collapsed with debts exceeding £319 million and made 1,150 employees redundant.
What Insolvency Means for an Insurance Programme
The insurance consequences of modular manufacturer insolvency cascade through the supply chain in ways that traditional construction insolvency does not. Specifically:
- For developers — partly-built projects with the manufacturer in administration face the immediate question of who completes the modules and who insures the work-in-progress. If the contractor's CAR was on a project-specific basis covering only completed modules delivered to site, the WIP value sitting in the failed manufacturer's factory may be uninsured
- For main contractors — manufacturer failure mid-contract is a force majeure event under some contracts but a contractor's risk under others. The CAR policy responds to physical damage, not to contractual delay from supplier insolvency; this is where trade credit insurance and supplier default cover become material
- For warranty providers — NHBC, LABC, and other warranty providers face the question of whether the structural warranty remains valid where the original manufacturer has dissolved. Warranty obligations transfer with the building, but enforcement against a dissolved manufacturer is impossible — and the warranty provider may have ultimate liability with no recourse
- For the manufacturer's own insurers — claims notified after the manufacturer's insolvency face complex run-off issues, particularly for PI and product liability claims that may arise years after the manufacturer ceases trading
The Replacement Cost Problem
When a modular manufacturer fails mid-project, replacing them is materially harder than replacing a conventional contractor. The manufacturer's design IP, BIM models, CNC files, and production tooling are all assets in the insolvent estate — accessible only through the administrator, often at a price, and sometimes not at all. In the Ilke Homes case, the IP was acquired in 2024 by a new company operating from an Irish email address, with the buyer offering completion services on the original Ilke designs — but with no continuity of the workforce, factory, or quality systems. From an insurance perspective, the practical effect is that "replacing" a failed modular manufacturer mid-project often means redesigning the modules to a different system — adding cost and time that the CAR insurer typically does not cover.
8. Building Safety Act, Second Staircases, and the Golden Thread
Higher-Risk Buildings and Modular
The Building Safety Act 2022 (BSA) and the associated higher-risk building (HRB) regime apply where a building is at least 18 metres or seven storeys high and contains two or more residential units. For modular residential development, this captures a meaningful share of the market — particularly for student accommodation, build-to-rent, and affordable housing schemes where MMC has been most actively used. Applicable schemes must navigate three regulatory gateways (planning, pre-construction approval, and pre-occupation registration) administered by the Building Safety Regulator (BSR).
The Second Staircase Rule and MMC Design
From 30 September 2026, all new residential buildings in England with any storey at 18 metres or above must have at least two staircases. This is particularly significant for volumetric modular schemes, where the structural grid and module dimensions were originally optimised around single-staircase configurations. Retrofitting a second staircase into an MMC design developed under the previous regime can require significant redesign, with implications for module sizing, services routing, and structural connections — all of which can affect insurability if the design changes are not properly captured in the golden thread of information.
The Golden Thread Requirement
The BSA introduces the "golden thread" — a digital record of building information that must be maintained throughout design, construction, and occupation. For MMC, this is potentially advantageous (factory-built components have inherently more documentation than site-built equivalents) but also creates new exposures: the manufacturer's BIM data, batch records, CoC certificates, and structural calculations all form part of the golden thread, and gaps or errors in this documentation can affect both BSR approval and the long-term insurability of the building.
From an insurance perspective:
- Latent defects and structural warranty providers are now reviewing golden thread documentation as part of underwriting; gaps can result in declined cover
- PI claims against MMC designers and manufacturers are increasingly framed around golden thread inadequacies as well as the underlying technical defect
- Mortgage lenders are starting to ask for evidence of golden thread compliance on HRB sales — affecting saleability of the finished units
- The principal designer role under the CDM Regulations 2015 has been expanded under the BSA to include building safety; PI cover for principal designers on HRB schemes must explicitly include this expanded duty
9. Latent Defects, Structural Warranty, and Mortgageability
For modular residential development, structural warranty is the single most important post-completion cover — without it, the units are not mortgageable, which means they cannot be sold to owner-occupiers and have limited resale market.
The Warranty Provider Landscape
NHBC Buildmark covers around 80% of UK new-build housing, with cover comprising deposit protection, a two-year builder warranty period, and a further eight years of insurance against structural damage. LABC Warranty, Premier Guarantee, Build-Zone, Buildsafe, Checkmate, Protek, and Global make up most of the remaining market. Each operates its own technical approval process, and each has its own approach to MMC.
For modular construction specifically:
- Some providers maintain pre-approved lists of MMC systems they will warranty; others assess each system individually
- Volumetric modular and unconventional structural systems typically require technical review of the system itself, not just the individual project
- Premium loadings for MMC versus traditional construction are common, particularly for newer or less-tested systems
- A small number of MMC systems have struggled to obtain mainstream warranty cover at all — which has been one of the commercial pressures behind the recent insolvencies
Commercial Latent Defects Insurance
For commercial MMC development — offices, hotels, schools, healthcare — structural warranty is replaced by commercial Latent Defects Insurance (LDI) or Inherent Defects Insurance (IDI), typically running for 10–12 years from practical completion on a no-fault basis. LDI is increasingly mortgageability-equivalent for commercial schemes and is often required by funders and institutional buyers. Like residential warranty, LDI underwriters are technically selective about MMC systems and often require additional technical due diligence — including witness inspections during factory production.
10. What Drives the Cost
| Rating Factor | Impact on Premium | What You Can Do |
|---|---|---|
| Construction system fire load | Highest single rating factor for manufacturers; CLT, mass timber, and SIPs attract significantly higher fire rates than steel or concrete-based systems | Specify sprinkler and L1 detection systems; implement and document JCoP-compliant hot work and waste procedures |
| Single-site value concentration | Aggregate value at the factory drives factory PD and BI premiums; high concentration limits insurer appetite | Consider distributed storage, fire compartmentation within the factory, and marshalling yard separation to reduce single-event loss exposure |
| Transit distance and method | Long road moves, particularly with abnormal load notifications, attract higher GIT/cargo rates; marine transit is rated separately | Plan routes carefully; use experienced abnormal load hauliers with appropriate certification; document loading and securing procedures |
| Project complexity and value | CAR rates scale with contract value but more steeply for high-rise, HRB, and complex schemes | For HRB schemes (18m+), engage with the BSR early and demonstrate gateway readiness to insurers |
| Supply chain financial standing | Insurers increasingly factor manufacturer financial standing into developer-arranged CAR rates post-2023 | Credit-check suppliers; obtain parent company guarantees where available; maintain contingency suppliers |
| Claims history and incident record | Factory fires, transit losses, and HSE prosecutions all materially affect renewal premiums for 5+ years | Invest in fire prevention, lifting procedure compliance, and documented health and safety; engage insurer risk engineers proactively |
| Latent defects / warranty appetite | Pre-approved MMC systems with established warranty acceptance attract lower premiums and broader availability | Use systems with established warranty pre-approval; document witness inspection regimes during factory production |
| BSA gateway readiness | For HRB schemes, demonstrated golden thread compliance and gateway approval reduce both PI and CAR premiums | Maintain comprehensive BIM, batch records, and CoC documentation from project inception |
11. Real Claims and How to Manage Them
Claim — Factory Fire, Timber Module Manufacturer
A UK timber-frame modular manufacturer suffered a significant fire originating in the spray booth area during weekend operations. Limited weekend supervision and a delayed detection response meant the fire spread to adjacent stock and partially-completed modules before the fire service contained it. Total physical damage was substantial: the spray booth was destroyed, an adjacent production cell was severely damaged, and approximately three weeks of work-in-progress was lost. Crucially, the loss occurred at the peak of the order book — modules were committed to four live development sites, all of which faced consequent delay.
The manufacturer's property insurance responded for the building and plant damage. Stock and WIP was covered on a reinstatement basis. The business interruption claim was the largest single element: with the production cell down for nine months pending equipment replacement, the BI claim ran into seven figures. The manufacturer had originally proposed a 12-month BI indemnity at policy inception; the broker had insisted on 18 months — a decision that proved decisive. Even with the 18-month period, the claim was close to the maximum indemnity, and full operations only returned in month 16.
The downstream consequences flowed through the supply chain. Three of the four developer clients triggered DSU claims under their developer-arranged CAR policies. The manufacturer's own product liability and contractual liability cover responded for liquidated damages on contracts where the manufacturer was unable to deliver to the original programme. The claim file ran for over two years from incident to final settlement.
The lesson: BI indemnity periods for modular manufacturers must reflect the realistic lead times for plant replacement, accreditation reinstatement, and order book rebuild — 12 months is typically inadequate, 18 months is the minimum we would now consider acceptable, and 24 months is increasingly justified for complex production lines.
Claim — Transit Damage to Bathroom Pods
A consignment of 32 fully-fitted bathroom pods being delivered to a London residential scheme suffered significant damage during a road transit incident. The carrier's tractor unit lost control on a motorway slip road, and the trailer carrying eight pods overturned. Six pods were destroyed beyond economic repair, and two were damaged at the corners — requiring factory return for assessment and either repair or scrap. Total claim value, including remanufacture, expedited freight on the replacements, and the consequent delay to the site programme, exceeded £400,000.
The claim ran into immediate complexity because the manufacturer, the haulier, and the main contractor each had different insurance arrangements. The haulier's goods-in-transit cover responded for the basic value of the pods damaged in their care. The manufacturer's specialist cargo policy responded for the consequent expediting costs of the replacement modules and the contractual liquidated damages exposure. The main contractor's CAR policy did not respond because the damage occurred before delivery to site — a wording that the contractor had not appreciated when signing the policy.
The lesson: when modules are in transit, the relevant policy is rarely the site CAR. Specialist marine cargo or GIT cover, with explicit attachment from factory loading bay and continuous cover through to site placement, is the only structure that reliably responds. Confirm in writing where each insurer's cover starts and ends, and confirm that there are no gaps.
Claim — Manufacturer Insolvency Mid-Project
A developer engaged in a 96-unit affordable housing scheme using a volumetric modular system faced manufacturer insolvency at module 41 of 96. The manufacturer entered administration with significant work-in-progress on the developer's project, including 12 modules in various stages of completion in the factory and design IP for the remaining 43 modules tied up in the insolvent estate.
The developer's CAR policy responded for the cost of the WIP at the factory at the date of the insolvency — but only after extended negotiations to establish ownership of the modules, which were technically still the manufacturer's stock pending paid completion under the contract terms. The developer also had to engage with the administrator to acquire access to the design files for the remaining modules, paying a separate fee for the licensed use of the IP.
The replacement manufacturer for the remaining modules quoted significantly above the original price and required a six-month design adaptation period to translate the original system into their own production lines. The total cost overrun, including the IP acquisition, replacement manufacturer premium, and the additional six months of project delay, exceeded £2.4 million — of which the CAR policy covered only a portion (the physical WIP value), the trade credit position covered another portion (the debtor balance owed by the manufacturer), and the developer absorbed the balance.
The lesson: where MMC schemes rely on a single manufacturer, supplier financial standing and contractual IP ownership provisions are as important as the insurance programme itself. Where the manufacturer's financial position is uncertain, parent company guarantees, escrowed design IP, and pre-agreed alternative suppliers all become commercial protections that supplement insurance — not replace it, but cover the exposures that insurance was never designed to handle.
Claims Management Steps
- For a factory fire or major property loss: attend to safety first, notify the fire service and HSE as required, then notify your insurer immediately. Preserve the scene to the extent safely possible — fire investigation will require forensic analysis. Pull stock records, WIP schedules, and contract commitments for all live projects within the first 48 hours.
- For a transit loss: document the scene with photographs, obtain the carrier's incident report, retain all loading records and route paperwork, and notify both the carrier's insurer and your own specialist cargo insurer. Do not move or scrap damaged modules until both insurers have inspected.
- For a manufacturer insolvency event: notify your CAR insurer immediately; the policy attachment to WIP at the manufacturer's premises is time-sensitive. Engage early with the administrator regarding access to IP and incomplete modules. Activate any trade credit insurance for outstanding payments owed to the manufacturer that may now be at risk.
- For a design or workmanship defect emerging post-completion: notify both your PI insurer and the structural warranty provider promptly. Do not undertake remedial work without the insurer's involvement — works undertaken before notification may not be reimbursed.
- For a lifting or installation incident: attend to injured persons first, secure the site, notify HSE if RIDDOR-reportable, and notify your PL and CAR insurers. Retain the lift plan, Appointed Person's records, and all sign-off documentation — these will be central to both the insurer investigation and any HSE inquiry.
Frequently Asked Questions
Employers' liability insurance is the only statutory legal requirement — mandatory if you employ anyone, minimum £5 million, with fines of £2,500 per day for non-compliance. Beyond that, the legal minimums depend on your role: contractors and developers face client and contractual requirements for public liability, contractors all risks, and professional indemnity, often as a condition of contract award. Manufacturers face product liability and PI as commercial necessities, plus property and BI to protect the factory itself. For higher-risk buildings under the Building Safety Act, additional documentation and PI scope requirements apply.
Often inadequately. Standard CAR wordings typically attach when materials arrive on site — which leaves the factory work-in-progress, off-site storage, and transit stages of MMC uninsured under the main project policy. For modular construction, the CAR wording must be specifically extended to cover off-site exposure at the manufacturer's premises, multi-stage transit, and lifting operations. We recommend reviewing existing CAR policies specifically against the MMC stages of work and obtaining explicit extensions or specialist standalone covers for the off-site components. Standard wordings will frequently leave material gaps.
Because modular construction concentrates flammable value — finished modules, work-in-progress, raw timber and SIPs, paint and adhesive stocks — into a single factory location, and into marshalling yards and partially-completed sites. A single fire can affect stock, modules, storage sites, transport staging, and unfinished structures all at once. This profile doesn't exist in conventional construction, where value is more thinly spread across long build programmes. Insurers have responded by tightening appetite, increasing deductibles, and requiring formal fire risk surveys and sprinkler systems for serious manufacturing risks. Specialist market placement is now standard for larger modular factories.
The impact depends on the contract structure and the policies in place. Work-in-progress sitting in the manufacturer's factory may be covered under your CAR policy's off-site extension, but only if that extension was specifically negotiated and only up to the policy limit for off-site values. Trade credit insurance can cover outstanding debtor balances. The replacement cost — finding an alternative manufacturer, acquiring IP from the administrator, and adapting designs — is typically not insured and represents the most significant uninsured loss. Given the wave of UK modular insolvencies between 2022 and 2025, supplier financial standing and contractual IP ownership protections are now as material as the insurance programme itself.
Yes, but the process is more complex than for traditional construction. NHBC, LABC Warranty, Premier Guarantee, Build-Zone, and other providers each maintain their own approach to MMC — some have pre-approved lists of modular systems, others assess each system individually with technical review. For volumetric modular and newer or less-tested systems, expect a technical pre-approval process taking 8–12 weeks and potentially attracting premium loadings versus traditional construction. The single most important step is securing warranty acceptance during the design phase, before contracting with the manufacturer — discovering at completion that the chosen system is unacceptable to the warranty provider is one of the most damaging commercial outcomes for an MMC developer.
For higher-risk buildings (18 metres or seven storeys with two or more residential units), the BSA introduces three regulatory gateways and the golden thread documentation requirement. The principal designer role has been expanded to include building safety — affecting PI scope and limits. From September 2026, all new residential buildings over 18 metres in England must have at least two staircases, which has design implications for modular schemes originally optimised around single-staircase configurations. Insurers and warranty providers increasingly review BSA gateway readiness and golden thread documentation as part of underwriting. Non-compliance with the BSA regime affects both insurability and the saleability of the finished units.
This is the highest-risk area for coverage disputes in MMC. Defects appearing at the interface between modular elements and site-built construction — foundations, brickwork, services connections — can be attributed to either party, with each insurer's response depending on the precise defect and the contractual allocation of design responsibility. Clarity in the design responsibility split, documented inspection regimes at each handover stage, and explicit contractual indemnification chains are essential. The more ambiguous the documentation, the longer claims take to resolve and the more likely you face an extended dispute across multiple insurers reserving their positions.
The range is wide. A small installer or specialist sub-contractor might pay £2,500–£6,000 per year for a combined policy. An MMC main contractor with £5m turnover might pay £8,000–£20,000 depending on the type of MMC and project profile. A volumetric or CLT manufacturer with serious factory exposure can pay £50,000–£250,000+ for the property, BI, product liability, and professional indemnity programme — driven by the single-site value concentration, the fire load, and the BI indemnity period. Developer-arranged programmes on individual MMC schemes are rated on contract value, scheme complexity, and BSA classification. The biggest cost drivers beyond size are: fire load of the construction system, single-site value concentration, claims history, and the financial standing of the supply chain.
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