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Deterioration of Stock (DOS) Insurance for Construction & Engineering: What It Covers, Who Needs It, and How to Get It Right
Introduction: why “stock” matters in construction and engineering
When people hear “stock,” they often picture retail shelves. In construction and engineering, stock can be just as critical—and far more time-sensitive. Many projects rely on materials that must be stored within strict temperature ranges or controlled conditions. If those conditions fail, the materials can become unusable, unsafe, or non-compliant.
That’s where Deterioration of Stock (DOS) insurance comes in. DOS is designed to protect businesses from the financial impact of perishable or temperature-sensitive stock being spoiled due to events like power failure, refrigeration breakdown, or accidental damage.
For construction and engineering firms, DOS can be relevant for:
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Contractors storing temperature-sensitive materials on site
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Engineering businesses holding specialist components in controlled environments
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Civil engineering firms working with resins, chemicals, adhesives, and coatings
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M&E contractors storing refrigerants, sealants, and specialist consumables
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Facilities and plant operators with refrigerated or controlled storage
This guide explains what DOS insurance is, how it works in a construction/engineering context, what to watch out for, and how to reduce claims risk.
What is Deterioration of Stock (DOS) insurance?
Deterioration of Stock insurance covers the loss of stock that becomes unfit for use because it deteriorates following a covered event.
In most UK commercial policies, DOS is either:
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An extension to a property policy (often under “Material Damage”), or
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A standalone section within a commercial combined policy
The key point: DOS is not “general wastage” cover. It’s intended for sudden, accidental incidents that cause stock to spoil.
What counts as “stock” for construction and engineering?
In construction and engineering, “stock” can include:
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Epoxy resins, grouts, and bonding agents
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Two-part adhesives and sealants
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Coatings, paints, and protective finishes with temperature limits
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Chemical additives and curing agents
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Specialist lubricants, oils, and fluids
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Battery packs or sensitive electronics/components requiring controlled storage
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Pre-fabricated materials that degrade under heat/humidity
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Temperature-sensitive PPE or consumables (less common, but possible)
If a material has storage conditions and becomes unusable when those conditions are breached, it may be a DOS exposure.
Why DOS insurance matters in construction and engineering
Construction and engineering projects are schedule-driven. If stock deteriorates, you don’t just lose the cost of materials—you can also trigger knock-on impacts such as:
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Delays waiting for replacements
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Re-work if compromised materials were installed
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Contractual penalties (liquidated damages)
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Increased labour and plant hire costs
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Disputes with clients or principal contractors
DOS insurance typically focuses on the value of the spoiled stock itself. However, understanding the broader operational impact helps you decide whether you also need:
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Business interruption cover (where applicable)
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Contract works cover for materials on site
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Engineering breakdown cover for plant and equipment
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Professional indemnity (if design/specification issues are involved)
Common causes of stock deterioration on construction and engineering risks
DOS claims often arise from a small number of recurring scenarios:
1) Power failure
A site compound, storage unit, or warehouse loses power due to:
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Local grid outage
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Tripped breakers
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Accidental damage to cables
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Overloaded circuits
If refrigeration or climate control stops, stock may exceed safe temperature ranges.
2) Refrigeration or temperature-control equipment breakdown
This can include:
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Refrigeration unit mechanical failure
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Compressor failure
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Thermostat malfunction
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Fan failure
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Refrigerant leaks
Engineering breakdown cover may be relevant here, because some policies only respond to DOS if the breakdown is insured.
3) Human error
Examples include:
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Doors left open on refrigerated units
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Incorrect temperature settings
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Stock stored in the wrong location
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Failure to rotate stock or follow manufacturer instructions
Some policies cover certain accidental human errors; others exclude “operator error” unless specifically included.
4) Fire, flood, or escape of water
Even if the stock isn’t burned or soaked, the event can:
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Cut power
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Damage refrigeration units
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Force emergency shutdowns
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Create unsafe contamination risks
5) Equipment damage during site works
Construction sites are dynamic. Refrigeration units, control panels, and cables can be damaged by:
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Vehicle impact
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Plant movement
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Vibration
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Accidental drilling/cutting into services
What does DOS insurance typically cover?
Coverage varies by insurer and wording, but DOS commonly covers:
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Cost of replacing stock that has deteriorated due to a covered cause
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Stock in cold rooms, fridges, freezers, or controlled stores
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Stock in transit (only if specifically included)
Depending on the wording, insured causes may include:
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Accidental failure of temperature-control equipment
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Accidental power failure (sometimes limited to public supply)
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Damage to refrigeration plant
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Fire and other insured perils causing spoilage
Valuation: what gets paid?
DOS claims are usually settled on one of these bases:
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Cost price (what you paid for the stock)
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Cost of replacement (what it costs to buy again now)
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Manufacturing cost (if you produce the stock)
Construction and engineering businesses should be clear on how stock is valued—especially if prices fluctuate or lead times are long.
What DOS insurance often does NOT cover (common exclusions)
This is where many claims fall down. Common exclusions include:
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Gradual deterioration (slow spoilage over time)
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Wear and tear / lack of maintenance of refrigeration equipment
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Known defects or pre-existing faults
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Incorrect storage contrary to manufacturer guidance
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Contamination (unless specifically included)
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Theft (that’s usually a separate peril)
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Consequential losses like delay penalties (unless insured elsewhere)
Some policies also limit cover to:
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Power failure from the public supply only (not your internal distribution)
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A maximum “hours clause” (e.g., failure must be rectified within X hours)
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A requirement for temperature records and alarm systems
DOS vs Contract Works: which one applies on site?
Construction businesses often assume contract works insurance will cover materials on site. Sometimes it will—but not always.
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Contract works typically covers physical loss or damage to materials and works in progress due to insured perils.
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DOS is specifically about stock becoming unusable due to temperature/control failure.
If you store temperature-sensitive materials in a site container and a cooling unit fails, the claim might be:
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A DOS claim (if included and conditions are met)
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A contract works claim (if the wording treats those materials as part of the contract works and includes spoilage)
The right answer depends on policy structure and definitions. This is why it’s important to describe your storage setup clearly when arranging cover.
DOS vs Engineering Breakdown: why the link matters
For engineering and construction firms, DOS is often connected to engineering breakdown (also called machinery breakdown).
If the deterioration is caused by a mechanical or electrical breakdown of refrigeration plant, some insurers require:
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Engineering breakdown cover to be in force, and/or
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The breakdown itself to be an insured event
If you only buy DOS without the underlying breakdown cover (or if breakdown is excluded), you can end up with a gap.
Who in construction and engineering should consider DOS cover?
DOS is most relevant if you hold stock that is:
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Temperature-sensitive
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High value
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Hard to replace quickly
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Critical to project timelines
Examples of businesses that may benefit:
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Civil engineering contractors using resins, grouts, and specialist chemicals
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Waterproofing and roofing contractors storing membranes, adhesives, and coatings
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M&E contractors storing refrigerants and specialist consumables
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Engineering workshops holding controlled components or sensitive electronics
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Infrastructure contractors with site compounds storing specialist materials
Even if your “stock” is not food or pharmaceuticals, deterioration can still be costly.
Key underwriting questions insurers will ask
To quote DOS insurance, insurers typically want clarity on:
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What stock is stored (type, value, and sensitivity)
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Maximum value at risk at any one time
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Storage method (cold room, fridge, container unit, warehouse)
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Temperature ranges required and monitoring approach
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Maintenance regime for refrigeration/control equipment
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Alarm systems and call-out arrangements
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Backup power (generator/UPS) and testing frequency
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Site security and access controls
Being prepared with this information can speed up quoting and reduce the risk of restrictive terms.
Risk management: how to reduce spoilage and strengthen your insurance position
Insurers like DOS risks that are well controlled. Practical steps include:
Temperature monitoring and records
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Use continuous monitoring where possible
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Keep logs (manual or digital)
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Set clear acceptable ranges per product
Alarm and response procedures
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High/low temperature alarms that notify out of hours
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Documented call-out list and response times
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Clear escalation if the first responder can’t attend
Preventive maintenance
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Planned maintenance schedule for refrigeration units
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Keep service reports and invoices
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Replace worn seals, fans, and sensors proactively
Backup power
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Generator sized to support refrigeration load
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Regular testing under load
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Fuel management plan
Stock management
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Avoid over-stocking beyond what you can safely store
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Rotate stock and track expiry dates (where relevant)
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Separate high-value stock to reduce total exposure
These steps don’t just reduce claims—they can also help you negotiate better premiums and terms.
Claims: what to do if stock deteriorates
If you suspect stock has deteriorated:
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Act immediately to prevent further loss (restore power, move stock, isolate affected items)
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Document the incident (photos, temperature logs, alarm records)
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Keep the stock if safe to do so—don’t dispose until the insurer agrees
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Notify your broker/insurer quickly and follow their instructions
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Gather evidence: maintenance records, purchase invoices, stock lists, and replacement quotes
The stronger your documentation, the smoother the claim is likely to be.
How to choose the right DOS sum insured
The sum insured should reflect the maximum value of susceptible stock at any one time.
Construction and engineering businesses should consider:
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Seasonal peaks (large projects, bulk purchasing)
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Long lead-time components
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Price volatility
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Whether stock is held across multiple locations (warehouse + site)
Under-insurance can reduce claim payments. Over-insurance can increase premium unnecessarily. A quick stock-at-risk review is usually worth doing.
Practical example scenarios (construction/engineering)
Scenario A: site compound power failure
A civil engineering contractor stores epoxy grout in a temperature-controlled container. A power cable is damaged during site works, shutting down the unit overnight. The grout exceeds the manufacturer’s maximum temperature range and must be disposed of.
Potential response: DOS extension may cover the replacement cost, subject to policy terms (public supply vs internal supply) and evidence of temperature breach.
Scenario B: refrigeration breakdown in an engineering workshop
An engineering firm stores sensitive components requiring controlled humidity and temperature. The control unit fails due to electrical breakdown. Components are compromised.
Potential response: DOS may respond if the breakdown is insured and maintenance records are in order.
Scenario C: door left open
A staff member leaves a controlled store door open after a late delivery. Temperature rises for several hours and materials are spoiled.
Potential response: depends on wording—some policies treat this as accidental damage; others exclude operator error.
Getting the cover right: what to tell your broker
To arrange DOS insurance that actually works when you need it, be specific about:
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The exact materials you store and why they’re sensitive
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Where they’re stored (site vs premises)
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The equipment used to control conditions
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Your monitoring, alarms, and maintenance
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Whether you need cover for internal power failure (not just public supply)
If you’re unsure, a broker can help map the risk to the right policy section—DOS, contract works, engineering breakdown, or a combination.
FAQ: Deterioration of Stock insurance for construction and engineering
Is DOS insurance only for food businesses?
No. Any business storing temperature-sensitive materials can have a DOS exposure, including construction and engineering.
Does DOS cover materials stored on a construction site?
It can, but it depends on the policy definitions and whether the site storage is declared. Some policies are premises-based unless extended.
Does DOS cover power cuts?
Often yes, but some policies restrict cover to failure of the public supply. If your risk is internal distribution failure, you may need specific wording.
Do I need engineering breakdown as well?
If spoilage is likely to be caused by mechanical or electrical breakdown of refrigeration/control equipment, engineering breakdown cover is often important.
Will DOS cover delay penalties on a contract?
Usually not. DOS typically covers the stock value. Contractual penalties may require other covers and careful contract review.
Next steps: protect your materials, projects, and cashflow
If your construction or engineering business stores temperature-sensitive materials—whether on site or at your premises—Deterioration of Stock insurance can be a smart way to protect your cashflow and keep projects moving.
If you’d like a quick review of your storage setup and the right way to structure cover (DOS, engineering breakdown, contract works, and business interruption), Insure24 can help.
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Call: 0330 127 2333
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Or request a quote online via insure24.co.uk