PRC & Non-Standard Construction Property Insurance UK
If your property is a system-built or precast concrete home — an Airey, a Cornish Unit, a Wates, a Reema, a BISF steel frame — you have almost certainly discovered that it doesn't behave like a brick house when it comes to money. Mainstream lenders hesitate, mainstream insurers decline, and the reason is a single word that follows many of these homes around: defective. Whether or not yours has been repaired, its construction type determines who will insure it and on what terms.
This guide is written for owners, landlords and portfolio holders of non-standard construction — with a particular focus on the precast reinforced concrete (PRC) types designated defective under the Housing Act 1985. It explains why these homes fall outside standard appetite, why the PRC Certificate is the document everything turns on, what you must disclose, and how a specialist market covers construction a portal won't. Non-standard construction sits in the same adverse lane as our RAAC property insurance guide — related, but a distinct problem: RAAC is about sudden failure of a roof panel, while PRC is about the long-term corrosion of a home's structural frame and its legal "defective" status.
Why does a non-standard construction property need specialist insurance treatment?
After the Second World War, the UK built roughly 1.5 million homes using non-traditional methods — system-built, prefabricated and precast — to plug an acute housing shortage at speed. Many were precast reinforced concrete: factory-made concrete panels and frames rather than brick and block. They solved a crisis, but decades later the engineering caught up with them. Where steel reinforcement is embedded in concrete, moisture and carbonation over time let the steel corrode; as it corrodes it expands, cracking and spalling the concrete and weakening the structure.
In the 1980s, prompted by defects found in a fire-damaged Airey house, the Building Research Establishment investigated and the Government legislated. The Housing Defects Act 1984 — later consolidated into Part XVI of the Housing Act 1985 — designated a list of PRC house types as inherently defective. For insurance, that designation is decisive: a standard, automated insurer treats designated-defective and non-standard construction as outside appetite, because durability, valuation and mortgageability are all in question. The risk drops out of the portal and into specialist territory.
For a landlord, this is not a technicality. A non-standard let that can't be insured through mainstream channels still needs continuous cover to satisfy a mortgage and to protect the asset — and getting that cover is a specialist placement, which is exactly the adverse-risk work Miller & Partner does.
The Insurability Framework™
A non-standard or PRC property is a textbook case for the Insurability Framework. Where a standard insurer sees "concrete construction" or "defective" and stops, our task is to turn the construction type, the repair status and the certification into a properly presented, defensible risk. We apply four pillars to every placement of this kind.
Underwriter Intelligence
We know which markets underwrite non-standard construction and what they need — the exact system type, the repair status, the PRC Certificate or Certificate of Structural Adequacy, and any engineer's report. Presenting these turns a decline into a quote.
Difficult Risk Expertise
PRC, steel frame and system-built homes fall outside standard appetite. We place them through specialist and Lloyd's-backed markets that assess the construction on its merits rather than declining on the keyword.
Risk Assessment
We identify the exposures non-standard construction creates — the reinstatement cost of a repaired build, the effect of an unrepaired neighbour, and underinsurance where the sum insured never reflected the true rebuild.
Claims Advocacy
A claim on a designated-defective home is complex, with construction and certification questions in play. You get a named broker who manages it with the underwriter and loss adjuster — not a call centre.
Key facts at a glance
- Around 1.5 million UK homes were built with non-traditional methods after the war — many precast reinforced concrete (PRC).
- The Housing Defects Act 1984, now Part XVI of the Housing Act 1985, designated around two dozen PRC types as defective.
- The core problem is corroding steel reinforcement, which cracks and spalls the concrete and weakens the frame over time.
- An unrepaired designated-defective home is very hard to mortgage and insure through mainstream markets.
- A PRC Certificate (or Certificate of Structural Adequacy) after an approved repair scheme is the document that unlocks lenders and insurers.
- Non-standard construction is broader than PRC — it includes steel-frame (BISF), cast-in-situ (no-fines), timber-frame and system-built homes.
- An unrepaired neighbouring unit in an attached property can affect your own mortgageability and cover.
What does "designated defective" actually mean for my insurance?
It is a specific legal status, not just a description. Under Part XVI of the Housing Act 1985, the Secretary of State designated named PRC house types as inherently defective because their construction could lead to structural failure over time — a defect that couldn't reasonably have been spotted in an ordinary survey at the time of purchase. The legislation gave original owners who had bought from the public sector under Right to Buy a route to assistance, and set the framework under which repairs were licensed and certified.
For insurance, the designation carries two messages to an underwriter: the construction has a recognised structural vulnerability, and the property's value and mortgageability may be impaired. Neither is fatal to obtaining cover, but both push the risk firmly out of the standard market. The key that reopens the door is evidence — that the home has been properly repaired and certified, or that its condition has been independently assessed.
Repaired or unrepaired — why does it change everything?
This is the single most important distinction for both mortgageability and insurance. A designated-defective PRC home that has been repaired under an approved scheme — typically by removing or encasing the original concrete frame and rebuilding in brick and block, then certified — behaves very differently in the market to one left in its original state. The table below sets out the split.
| Factor | Unrepaired designated-defective | Repaired & certified |
|---|---|---|
| Structure | Original PRC frame in place | Rebuilt in brick/block or encased |
| Key document | Structural engineer's report | PRC Certificate / Certificate of Structural Adequacy |
| Mortgageability | Mostly cash / specialist only | Acceptable to specialist lenders |
| Insurer appetite | Narrow — specialist / adverse placement | Broader — non-standard specialist markets |
| Neighbour effect | Unrepaired attached unit is a further flag | Adjoining repair status still relevant |
| Typical outcome | Placeable via specialist with an engineer's report | Placeable, well-priced, with certification |
"The cases that catch people out are the inherited ones — someone buys an ex-council house cheaply, not realising it's an unrepaired Cornish Unit, and only finds out when the insurer or the lender flags the construction. Suddenly the bargain has a very specific problem attached to it, and they had no idea going in."
"What we've learned is that the certificate is everything. A repaired PRC home with a proper PRC Certificate and an engineer's confirmation is a genuinely placeable risk — we do them regularly. The same house repaired 'to a good standard' but with nothing on paper is a much harder conversation, because the market can't take the owner's word for the structure."
Which construction types are affected?
"Non-standard" is an umbrella covering many distinct systems, and the specific name drives how insurers and valuers treat the property. The designated-defective PRC list includes types such as Airey, Boot, Cornish Unit, Dorran, Gregory, Myton, Newland, Orlit, Parkinson, Reema, Schindler, Stent, Tarran, Underdown, Unity, Waller, Wates, Wessex, Winget and Woolaway, among others. Beyond designated PRC, insurers also treat as non-standard: steel-frame homes such as BISF and Trusteel; cast-in-situ concrete such as Wimpey no-fines; and timber-frame and other system-built panel homes.
The practical point is that the first job on any case is to identify the construction precisely, because the system name determines which markets will even look at it. A vague "concrete house" gets nowhere; "repaired Cornish Unit Type II with PRC Certificate" gets a considered quote.
What is a PRC Certificate and why does it matter so much?
A PRC Certificate — closely related to a Certificate of Structural Adequacy — is issued after a designated-defective home has been repaired under a recognised, licensed scheme (historically administered through bodies such as PRC Homes Ltd), confirming the work meets the required standard and the structure is sound. It is the document lenders and insurers rely on to treat the property as an acceptable, if non-standard, risk.
Without it, even genuine repairs may not open the market, because the certificate is what independently vouches for the structure. With it, a specialist can place the property much as they would any other non-standard home. If your property was repaired but you don't hold the certificate, obtaining a retrospective certificate or an approved engineer's assessment is usually the single most valuable step you can take — much as it is for a subsidence-history property and its Certificate of Structural Adequacy.
Do I have to declare the construction type?
Yes, unambiguously. The construction type of a property is a material fact — arguably the material fact for a non-standard home — and under the Insurance Act 2015 you must disclose it as part of a fair presentation of the risk. Buying cover for a designated-defective PRC house as though it were standard brick construction, whether by omission or because a portal never asked, is a direct route to a declined claim: if a loss occurs and the insurer discovers the true construction, it can avoid the policy or reduce the payout.
The right approach is to state the construction and repair status plainly, provide the certificate or engineer's report, and let a specialist price it accurately. A properly disclosed non-standard home is a policy that pays; a mislabelled one is a policy that fails.
Cover Checker: what does your construction type need?
Pick the construction closest to yours to see the cover a specialist builds around it. Indicative only — your placement is built around your exact type, repair status and certification.
Is your non-standard property underwriter-ready?
Tick each item you can already evidence. The more you tick, the closer your property is to a clean specialist placement. Blanks are what to resolve before going to market.
- I know the exact construction type (e.g. Airey, Cornish, BISF)
- I know whether it is designated defective
- I know the repair status (repaired / original)
- I hold a PRC Certificate / Certificate of Structural Adequacy
- Repairs were done under an approved / licensed scheme
- I have (or can get) a structural engineer's report
- Any attached neighbouring units are repaired too
- My rebuild sum insured reflects the actual construction
How insurable is your non-standard property right now?
Two questions give an indicative insurability tier. Guidance only — not a quote or a survey.
What drives the premium on a non-standard property?
With a specialist market, the premium on a non-standard home turns on the construction and its documentation more than anything else. As ever, the mitigation column is where owners have real influence — on a PRC or system-built property, evidence genuinely reprices the risk.
| Rating factor | Why it raises the premium | How to mitigate it |
|---|---|---|
| Construction type | PRC / system-built carries structural concern | Identify the exact type precisely |
| Designated defective | Legal defective status narrows appetite | Evidence repair and certification |
| Repair status | Unrepaired frames are highest concern | Repair under an approved scheme |
| Certification | No certificate = no evidence for the market | Obtain PRC Certificate / Certificate of Structural Adequacy |
| Structural condition | Spalling / cracking raises risk | Provide a structural engineer's report |
| Neighbouring units | Unrepaired attached units flag the risk | Evidence adjoining repair status |
| Reinstatement value | Underinsurance drives caution | Set the sum insured to actual rebuild cost |
| Use / occupancy | Let / portfolio rated above owner-occupied | Match cover to use; disclose fully |
| Age & maintenance | Poorly maintained stock concerns insurers | Evidence upkeep and any upgrades |
| Location | Standard flood/subsidence loadings apply too | Provide postcode-level risk data |
| Claims history | Prior claims compound the non-standard flag | Present context and remedial work |
| Disclosure quality | Vague presentation gets declined or loaded | Present a full, precise construction picture |
How do owner and landlord duties interact with a non-standard property?
Letting a non-standard home carries the usual duties, with the construction adding weight. The Homes (Fitness for Human Habitation) Act 2018 requires a let property to be free from serious hazards, and structural condition, damp and thermal performance — all recurring issues in PRC and system-built stock — fall squarely within that. Keeping continuous, correctly-valued buildings cover in force is central to discharging these duties and to satisfying a mortgage, because an uninsured non-standard property that suffers a loss it cannot fund to reinstate is a problem for the tenant, the lender and the owner at once. Where the property is designated defective, staying on top of the repair and certification position — and disclosing it accurately — is part of managing it responsibly, not merely a route to a cheaper premium.
Three real-world claim scenarios non-standard owners should learn from
These are fictionalised composites of the placements and claims we see, with realistic figures. The first two show the classic ways non-standard cover fails; the third shows it working.
The undisclosed Cornish Unit
A landlord bought an ex-council house cheaply and insured it online as a standard 1950s property, ticking "brick" because the form offered nothing better and the render looked conventional. It was in fact an unrepaired, designated-defective Cornish Unit. When a serious escape of water caused major damage, the loss adjuster identified the PRC construction — never disclosed — and the insurer had grounds to act.
Because the construction type is a material fact under the Insurance Act 2015, the non-disclosure let the insurer avoid the policy, and the landlord funded the reinstatement before placing correct cover through a specialist.
The underinsured repaired PRC
A repaired PRC home — properly certified, rebuilt in brick and block — had been insured for years to an old figure of £150,000 that no one had revisited. A fire caused significant damage, and the true cost to reinstate the property came to £240,000, meaning it was insured at around 63% of its rebuild cost.
Correctly placed and certified, the policy responded — but because the sum insured was well below the true reinstatement value, the condition of average reduced the £90,000 loss proportionately, leaving a shortfall of around £34,000.
The properly-placed repaired Airey
A repaired Airey house, rebuilt under an approved scheme with a PRC Certificate and a structural engineer's confirmation, was placed through a specialist non-standard market with the construction and certification fully disclosed and the sum insured set to a current rebuild figure. When a severe storm caused structural and water damage, the claim was handled cleanly.
The £38,000 of damage was met in full, because the property had been correctly identified, certified, disclosed and valued from the outset — a non-standard home behaving exactly like a standard one at the point of claim.
How to insure a non-standard property: a step-by-step approach
If you own or let a PRC or non-standard home, work through these eight steps in order. Done properly, they turn a construction the mainstream declines into one a specialist prices fairly — and a claim that actually pays.
- Identify the construction precisely. Establish the exact system type (Airey, Cornish Unit, Wates, BISF and so on) — the name drives which markets will look at it.
- Check the defective status. Confirm whether the type is designated defective under Part XVI of the Housing Act 1985, as this shapes both mortgageability and insurance.
- Establish the repair status. Determine whether the property has been repaired under an approved scheme, and to what standard.
- Obtain the certificate. Secure the PRC Certificate or Certificate of Structural Adequacy — or a retrospective certificate / engineer's report if repairs were done without one.
- Get a structural engineer's report. Where the property is unrepaired or the condition is uncertain, an engineer's assessment gives the market something concrete to price.
- Check neighbouring units. For attached properties, establish the repair status of adjoining units, as an unrepaired neighbour can affect your own position.
- Set the sum insured properly. Base it on the true rebuild cost of the actual construction — repaired brick/block or otherwise — not a generic estimate.
- Disclose fully and place with a specialist. Present the full construction and certification picture to a broker with specialist non-standard and Lloyd's market access, and review at each renewal.
John Miller
John has 13+ years placing property risks that standard markets decline, with direct access to Lloyd's and specialist non-standard schemes. PRC and system-built construction — Airey, Cornish, Wates, Reema, BISF and more, repaired and unrepaired, owner-occupied and let — is a core part of Miller & Partner's practice. If your non-standard property has been refused, mispriced or mislabelled, John's team identifies it correctly and places it with the markets that will cover it. More about John.
PRC & non-standard construction glossary
- PRC (precast reinforced concrete)
- Construction using factory-made concrete panels and frames reinforced with embedded steel, common in post-war system-built homes.
- Non-standard construction
- Any construction other than traditional brick or block cavity walls — including PRC, steel frame, cast-in-situ concrete and timber frame.
- Designated defective
- A legal status under Part XVI of the Housing Act 1985 applied to named PRC house types found to be inherently defective.
- Housing Defects Act 1984
- The legislation that first identified defective PRC housing, later consolidated into the Housing Act 1985.
- Housing Act 1985 Part XVI
- The consolidated framework designating defective dwellings and providing assistance to affected owners.
- PRC Certificate
- Certification issued after an approved repair of a designated-defective home, confirming the work and structure meet the required standard.
- PRC Homes Ltd
- The body historically associated with licensing and certifying approved PRC repair schemes.
- Certificate of Structural Adequacy (CSA)
- A structural engineer's certificate confirming a repaired property is structurally sound — closely related to a PRC Certificate.
- Approved repair scheme
- A recognised, licensed method of repairing a defective PRC home, typically rebuilding in brick and block or encasing the frame.
- Spalling
- The cracking and flaking of concrete caused by corroding steel reinforcement expanding within it.
- Carbonation
- A chemical change in concrete over time that reduces its protection of the embedded steel, allowing corrosion.
- Rebar corrosion
- Rusting of the steel reinforcement inside concrete — the root cause of PRC structural defects.
- BISF house
- A steel-framed post-war house type (British Iron and Steel Federation), treated as non-standard construction.
- No-fines concrete
- Cast-in-situ concrete without fine aggregate, used in types such as Wimpey no-fines — non-standard construction.
- System-built
- Homes assembled from prefabricated components rather than built conventionally on site.
- Reinstatement cost
- The true cost to rebuild the property in its actual (repaired or original) construction after a loss.
- Condition of average
- A clause that reduces a claim proportionately where the sum insured is below the true reinstatement value.
Frequently asked questions
Yes, but usually through a specialist market rather than a price-comparison site. Mainstream insurers often decline PRC and system-built construction. A specialist underwrites it around the exact construction type, the repair status and the certification — and a repaired, certified home is a genuinely placeable risk.
It's a legal status under Part XVI of the Housing Act 1985 applied to named PRC house types found to be inherently defective because their structure can deteriorate over time. For insurance it signals a recognised structural concern and possible value or mortgage impairment, which pushes the risk into specialist territory — but doesn't make it uninsurable.
Yes — it's arguably the single most material fact about a non-standard home, and must be disclosed under the Insurance Act 2015. Insuring a PRC house as though it were standard brick, whether deliberately or because a portal never asked, is a direct route to a declined claim.
The designated-defective PRC list includes types such as Airey, Boot, Cornish Unit, Dorran, Orlit, Reema, Unity, Wates, Winget and Woolaway, among others. Beyond designated PRC, insurers also treat steel-frame (BISF), cast-in-situ (no-fines) and timber-frame homes as non-standard. Identifying the exact type is the essential first step.
A PRC Certificate — related to a Certificate of Structural Adequacy — is issued after a designated-defective home has been repaired under an approved scheme, confirming the structure is sound. You need it because it's the evidence lenders and insurers rely on; without it, even genuine repairs may not open the market.
Often yes, but it's a specialist placement and usually needs a structural engineer's report so the market has something to assess. Unrepaired designated-defective homes sit outside standard appetite, so they're placed through specialist and Lloyd's-backed insurers rather than the mainstream.
Close to it, once it's repaired under an approved scheme and certified. It's still non-standard, so it's placed through specialist markets, but a repaired, certified, correctly-disclosed and correctly-valued home is a straightforward proposition — and, as our claim examples show, it responds just like a standard property.
It can, for attached properties. An unrepaired neighbouring unit is a flag for both lenders and insurers, because the structural condition of an adjoining home can bear on your own. Evidencing the repair status of attached units helps present a cleaner risk.
Yes. Non-standard construction is broader than PRC — steel-frame types such as BISF and Trusteel, cast-in-situ concrete such as Wimpey no-fines, and timber-frame and system-built panel homes all fall outside standard appetite and are usually best placed through a specialist.
It does, and it's easy to get wrong. The sum insured should reflect the true cost of reinstating the actual construction — a repaired PRC home rebuilt in brick and block, for example. A generic estimate or an old figure risks under-insurance and the condition of average, as one of our claim examples shows.
A refusal from a standard insurer or a portal is normal for non-standard construction, not a verdict. A specialist broker can identify the exact type, gather the certificate or an engineer's report, and present it to markets that actively underwrite PRC. The issue is almost always the market it was offered to, not the property.
Almost certainly. A specialist broker is the difference between a decline and a fairly-priced quote on a PRC or system-built home. Miller & Partner places non-standard construction — repaired and unrepaired, owner-occupied and let — through Lloyd's-backed and specialist markets, and approaches every case through The Insurability Framework — underwriter intelligence, difficult-risk expertise, risk assessment and claims advocacy.
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