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Why Are Cornish Units Unmortgageable?
Cornish Unit homes are a type of Precast Reinforced Concrete (PRC) construction that was designated as "defective" under the Housing Defects Act 1984, because the concrete can deteriorate and the steel reinforcement corrode. Most mainstream lenders won’t mortgage an unrepaired Cornish Unit, since it’s considered structurally unsound and hard to resell. They become mortgageable only after a PRC-certified structural repair. Unrepaired ones typically sell to cash buyers.
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- PRCdefective construction
- Certified repairrestores mortgage
- 7-28 dayscash if unrepaired
What a Cornish Unit is
A Cornish Unit is a type of Precast Reinforced Concrete (PRC) house, built in large numbers (often as council housing) in the mid-20th century. Like other PRC types, it was constructed from prefabricated concrete components with steel reinforcement. There are two "marks" of Cornish Unit, recognisable by their distinctive design (often a concrete ground floor with a mansard-style upper). They were a quick post-war housing solution, but the construction method has proven problematic over time.
Why they’re defective
| Issue | Why it matters |
|---|---|
| Concrete deterioration | Degrades over decades |
| Steel reinforcement corrosion | Weakens the structure |
| Housing Defects Act 1984 | Officially designated "defective" |
| Resale difficulty | Lenders see them as a risk |
The core problem is that the concrete and embedded steel deteriorate, raising structural concerns — which is why they were formally designated defective.
Why lenders won’t mortgage them
Mainstream mortgage lenders avoid unrepaired PRC homes like Cornish Units because they’re considered structurally unsound, hard to resell, and a poor security risk. If a lender can’t be confident the property will hold its value and stand the test of time, they won’t lend — which removes most ordinary buyers. This creates a self-reinforcing problem: hard to mortgage means hard to sell, which keeps values down. It’s the construction type, not the individual home’s tidiness, that lenders object to.
How they become mortgageable
A Cornish Unit can be made mortgageable through an approved PRC structural repair scheme — essentially rebuilding the structural elements to a recognised standard — certified with a PRC Certificate (often by a structural engineer or under a licensed repair scheme). Once fully and properly repaired and certified, many lenders will then consider a mortgage. A partially repaired Cornish Unit, or one repaired without proper certification, often remains unmortgageable, so the certification is key.
Selling a Cornish Unit
If your Cornish Unit is repaired and PRC-certified, you can sell it much like any house, to mortgage buyers — keep the certificate and repair documentation to hand. If it’s unrepaired, the realistic market is cash buyers and investors who either repair it themselves or hold it. A cash buyer experienced with PRC and non-standard construction can purchase as-is in 7-28 days, without a lender. The trade-off is a price reflecting the construction and any repair needed. See non-standard construction.
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Written & reviewed by Lisa Hayes, Founder
Lisa Hayes is the founder of Ready Steady Sell and an independent UK home-selling expert with over a decade helping homeowners weigh cash house buyers, property investors and the wider fast house-sale industry — without pressure or hidden fees. Every guide is reviewed for accuracy under our editorial standards.
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Frequently asked questions
Straight answers, no sales talk
Why are Cornish Units unmortgageable?
They’re a defective PRC (precast reinforced concrete) construction, designated defective under the Housing Defects Act 1984. The concrete deteriorates and steel corrodes, so most lenders won’t mortgage an unrepaired one.
What is a Cornish Unit?
A type of precast reinforced concrete house built in large numbers mid-20th century, often as council housing, with a distinctive design and prefabricated concrete components with steel reinforcement.
Can a Cornish Unit be made mortgageable?
Yes — through an approved PRC structural repair scheme, certified with a PRC Certificate. Once fully and properly repaired and certified, many lenders will consider a mortgage.
Why won’t lenders mortgage PRC homes?
They’re considered structurally unsound, hard to resell and a poor security risk. Lenders can’t be confident the property will hold value, so they won’t lend on an unrepaired one.
Can I sell an unrepaired Cornish Unit?
Yes — to cash buyers and investors who repair or hold it. A cash buyer experienced with PRC construction can purchase as-is in 7-28 days without a lender.
Does a partial repair make it mortgageable?
Usually not — a partially repaired Cornish Unit, or one repaired without proper PRC certification, often remains unmortgageable. Full repair and certification is key.