CAR and EAR Treaties: Structuring Construction & Erection Reinsurance
CAR and EAR Treaties Explained: Structuring Construction and Erection Reinsurance
By Hitul Mistry | Last reviewed: March 2026
Construction is where economic ambition becomes physical risk, and the reinsurance behind it rarely gets the attention it deserves until a crane collapses or a flood inundates an open excavation. Global construction spend is forecast to grow by more than USD 4 trillion this decade, with much of it concentrated in the energy-transition and infrastructure projects that dominate erection risk (Oxford Economics; Aon Construction & Infrastructure Report). Natural catastrophes now drive insured losses well above USD 100 billion in heavy years (Swiss Re Sigma, 2025; Munich Re NatCatSERVICE), and construction sites — with structures half-built, materials stockpiled, and defences incomplete — sit squarely in the path. Contractors All Risks (CAR) and Erection All Risks (EAR) treaties are the mechanisms that let insurers write these projects, and structuring them well is the difference between a stable account and a volatile one.
What separates CAR from EAR risks?
CAR and EAR are sister covers under the engineering umbrella, but they respond to fundamentally different exposure profiles — one dominated by civil works, the other by the machinery that goes into them.
1. Contractors All Risks (CAR)
- Covers building and civil-engineering works: foundations, structures, roads, bridges, and the materials and labour that build them.
- The dominant exposures are natural catastrophe, fire, collapse, and defective workmanship on site.
2. Erection All Risks (EAR)
- Covers the installation and erection of plant and machinery — turbines, boilers, process trains, and electrical systems.
- The dominant exposure shifts to testing and commissioning, when equipment is first energised and stressed.
3. Overlapping and hybrid projects
- Large projects — a power plant or refinery — contain both civil works and plant erection, blurring the CAR/EAR line.
- Underwriters allocate the dominant characteristic or split the risk, which drives treaty attachment and rating.
4. Common threads
- Both are project-length, all-risks covers with defined maintenance periods and defect considerations.
- Both expose reinsurers to single-site accumulation and, increasingly, to delay-driven financial loss.
How is the policy period itself a risk?
Unlike an annual property policy, a construction or erection cover runs for the life of the project, so the policy period itself becomes an exposure variable that reinsurers must structure around.
1. Multi-year, single-premium logic
- A project premium set at inception must respond across several construction seasons and a steadily rising sum insured.
- Getting the exposure curve wrong early compounds over years rather than resetting at annual renewal.
2. Risks-attaching treaty basis
- Construction accounts are typically ceded on a risks-attaching basis so the treaty in force at inception covers the whole project period.
- This requires disciplined run-off management as projects extend beyond the treaty year.
3. Rising and shifting exposure
- The insured value climbs as materials arrive and structures rise, peaking near completion.
- The nature of the exposure also shifts — from ground-works and flood risk early, to plant and fire risk late.
4. Extensions and overruns
- Project delays extend the exposure period, sometimes beyond the original completion date and premium basis.
- Reinsurers watch overruns closely because they stretch both physical and DSU exposure without matching premium.
Which treaty structures underpin CAR and EAR accounts?
Construction reinsurance relies on proportional treaties for the bulk working account, layered with non-proportional protection for severity and catastrophe, and facultative for the largest single risks.
1. Proportional treaties — quota share and surplus
- Quota share cedes a fixed share of every CAR/EAR risk, smoothing a volatile account and sharing catastrophe outcomes.
- Surplus treaties let the cedent keep smaller projects net while ceding lines on larger sums insured, shaping net exposure by size.
2. Per-risk excess-of-loss
- Per-risk XL caps the net loss from any single project after proportional cessions, protecting against a large collapse, fire, or plant failure.
- Attachment and limit are set against the largest probable single-site loss, not the treaty aggregate.
3. Catastrophe excess-of-loss
- Cat XL responds when one windstorm, flood, or earthquake damages multiple insured sites simultaneously.
- It is the primary defence against the correlated, multi-project accumulation that defines the class.
4. Facultative for jumbo projects
- Mega-projects with sums insured or DSU periods beyond treaty capacity are placed facultatively, risk by risk.
- Facultative lets reinsurers underwrite the specific engineering, siting, and schedule of a named project.
The comparison below sets out how the main structures divide the work of a construction reinsurance programme.
| Structure | Primary purpose | Responds to | Typical placement |
|---|---|---|---|
| Quota share | Volatility smoothing | Every ceded risk pro rata | Whole account |
| Surplus | Net exposure by risk size | Larger sums insured | Whole account |
| Per-risk XL | Single-project severity | One large project loss | Above proportional net |
| Catastrophe XL | Multi-site accumulation | One nat-cat event, many sites | Portfolio protection |
| Facultative | Jumbo / non-standard risk | Named mega-project | Individual risk |
Why do maintenance periods and testing dominate loss experience?
Two phases carry disproportionate loss potential in construction and erection — the testing and commissioning of new plant, and the maintenance period after handover — and both need explicit reinsurance attention.
1. Testing and commissioning
- Energising plant for the first time stresses equipment at its most vulnerable, concentrating machinery-breakdown-type losses.
- EAR wordings often sub-limit hot testing or restrict its duration because of this concentration.
2. Maintenance and defects-liability period
- After handover, a maintenance period of 12 to 24 months covers damage arising from earlier construction activity.
- Extended maintenance broadens this to defects that first manifest during the period, lengthening the tail.
3. Defect interaction
- Testing frequently exposes latent design or workmanship defects, connecting these phases to the LEG defect wordings.
- Reinsurers align maintenance terms with the underlying defect basis to avoid coverage mismatch.
4. Structuring implications
- Sub-limits, time bars, and commissioning warranties are common treaty and facultative conditions.
- The reinsurer's retention and XL attachment must contemplate a peak that arrives late in the project life.
How do ALOP and DSU change the loss picture?
Advance loss of profits (ALOP), also called delay in start-up (DSU), converts a physical-damage event into a financial loss tied to the project schedule, and it can dwarf the material damage that triggered it.
1. What ALOP/DSU covers
- It indemnifies the principal for lost revenue or extra financing cost when insured damage delays the commercial operation date.
- The trigger is insured physical damage on the critical path, not any delay whatsoever.
2. The critical path drives severity
- A modest loss on a critical-path activity can generate months of delay and a DSU claim far larger than the repair.
- Long-lead replacement items — a bespoke turbine or transformer — magnify the delay and the indemnity.
3. Reinsurance treatment
- DSU is often written with its own indemnity period, deductible in days, and daily value of loss.
- Reinsurers load explicitly for DSU and may sub-limit or exclude it where schedule data is weak.
4. Underwriting the schedule
- The project programme becomes a rating input, with float, sequencing, and procurement lead times all relevant.
- Quantifying DSU demands schedule literacy that traditional property rating does not require.
How do reinsurers manage nat-cat accumulation and pricing?
Catastrophe accumulation across many exposed sites, priced on a moving exposure base, is the defining technical challenge of construction reinsurance — and where modern data tooling changes the game.
1. Site-level accumulation control
- A single windstorm, flood, or quake can hit dozens of insured sites at once, correlating losses that look independent on paper.
- Geospatial mapping of every active site against hazard footprints reveals the true single-event exposure.
2. Vulnerability of partial works
- Half-built structures, open excavations, and incomplete drainage are often more fragile than the finished asset.
- Catastrophe models increasingly reflect construction-phase vulnerability rather than assuming completed-value resilience.
3. Exposure and experience rating
- Pricing blends exposure rating on time-phased sums insured with experience rating where the account is credible.
- Explicit loadings capture testing risk, DSU, and the catastrophe component that experience alone under-represents.
4. Data-driven exposure capture
- Parsing project schedules, locations, and values into time-phased exposure sharpens both pricing and accumulation views.
- Portfolio dashboards let reinsurers watch aggregate DSU, single-site peaks, and cat exposure as the book evolves.
InsurNest helps construction and erection reinsurers digitise exposure capture, map site-level catastrophe accumulation, and model ALOP/DSU severity — turning schedules and locations into a live, priced view of the portfolio rather than a static bordereau.
Frequently Asked Questions
What is the difference between CAR and EAR insurance?
Contractors All Risks (CAR) covers civil and building works dominated by materials, labour, and structures, while Erection All Risks (EAR) covers the installation and erection of plant and machinery where the dominant exposure is testing and commissioning of equipment.
How are CAR and EAR risks reinsured?
They are typically reinsured through proportional treaties — quota share and surplus — for the working account, backed by per-risk excess-of-loss for single-project severity and catastrophe XL for multi-site nat-cat accumulation, with facultative used for jumbo projects.
What is the policy period risk in construction reinsurance?
Construction and erection policies run for the length of the project rather than 12 months, so a single premium must cover a multi-year, rising exposure across several catastrophe seasons, which conventional annual treaties handle on a risks-attaching basis.
Why is the testing and commissioning phase so critical?
Testing and commissioning energises installed plant for the first time, concentrating the highest sums insured and the greatest chance of machinery failure, so it is often the single most loss-prone phase of an EAR risk.
What is a maintenance period in a CAR or EAR policy?
The maintenance or defects-liability period extends cover after handover — usually 12 to 24 months — for damage arising from construction activity or, under extended maintenance, from defects that manifest during that time.
What is ALOP or DSU cover in construction reinsurance?
Advance loss of profits (ALOP), also called delay in start-up (DSU), indemnifies the principal for lost revenue or added financing cost when insured physical damage delays the project's completion and commercial operation date.
How does nat-cat accumulation affect construction sites?
A single windstorm, flood, or earthquake can strike many exposed sites at once, and partially built structures are often more vulnerable than finished ones, making catastrophe accumulation a defining concern for construction reinsurers.
How do reinsurers price construction and erection treaties?
Pricing blends exposure rating on time-phased sums insured, experience rating where credible, explicit loadings for testing risk and DSU, and catastrophe modelling of site accumulation, increasingly supported by data-driven exposure capture.
Sources
- Swiss Re Sigma — natural catastrophe and construction research
- Munich Re — NatCatSERVICE and construction risk
- Aon — Construction and Infrastructure market insights
- Guy Carpenter — construction and engineering reinsurance insights
- Gallagher Re — reinsurance market and specialty reviews
- Oxford Economics — Global Construction Futures
- Lloyd's — construction and engineering class guidance
Editorial note: Statistics in this article come from public industry research and are used for educational illustration. Construction and erection exposures differ materially by project, geography, and wording; InsurNest does not guarantee specific results, and this content is not underwriting, legal, or actuarial advice.
CAR and EAR treaties only work when the tower matches the project — InsurNest helps reinsurers structure, price, and monitor construction risk with better data.
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