What it is
A precast reinforced concrete (PRC) house is built from concrete columns, beams and wall panels that were cast in a factory or yard and then assembled on site. Steel reinforcement inside the concrete gives it strength. Most PRC houses were built in the late 1940s and 1950s, when councils needed homes quickly and bricks and skilled bricklayers were scarce.
There were many different systems, each with its own name. Types you may come across include Airey, Cornish Unit, Reema, Orlit, Unity, Woolaway, Wates, Boot, Dorran, Tarran and Parkinson. They differ in how the columns and panels fit together, which affects how each is identified and repaired.
What went wrong
Problems came to light in the early 1980s. After a serious fire in an Airey house in Barnsley, the Building Research Establishment (BRE) was asked to investigate. In May 1981 it reported that the concrete parts of Airey houses were liable to crack and eventually break up because of carbonation and, in some cases, high levels of chloride. Investigations of other PRC types followed.
Concrete normally protects the steel inside it from rusting. Over the years, carbon dioxide from the air reacts with the concrete, working inwards from the surface. This is carbonation. When it reaches the steel, that protection is lost and the steel can corrode, especially if the concrete is damp or contains chlorides. Rust takes up more space than steel, so corroding reinforcement cracks the concrete around it and can make pieces break away. PRC components are often slim, so the concrete covering the steel can be thin.
When the BRE findings were reported to Parliament in 1984, most of the houses studied were structurally sound. But the rate of deterioration varied widely, both between types and within them, and it was expected to continue.
Designation and the Housing Defects Act 1984
Parliament passed the Housing Defects Act 1984 to help people who had bought these houses from councils and other public bodies before the defects became generally known. Its provisions were later consolidated into Part XVI of the Housing Act 1985.
Under this legislation the government designated classes of house as defective. When the Bill was debated in April 1984, the Minister for Housing and Construction listed 28 PRC types to be designated, including Airey, Boot, Cornish Unit, Dorran, Orlit, Parkinson Frame, Reema Hollow Panel, Tarran, Unity, Wates and Woolaway. Eligible owners could apply for a grant towards repair or, in some cases, to have the house bought back, within a period set by each designation. Your conveyancer can advise whether anything still applies to a particular house.
Designation applies to a type of house. It does not mean every house of that type is failing, and each house has to be judged on its own condition and repair history.
Repairs and certificates
To give lenders confidence in repaired houses, the National House-Building Council (NHBC) set up a subsidiary, PRC Homes Ltd. It licensed repair systems and the firms that carried them out, approved inspectors to check the work, and issued a warranty on completion.
The principle of a licensed repair was that concrete parts that could be defective should no longer carry the weight of the house. They were either removed and replaced, often with new brick or block walls, or a new structure was added to take the load. Many repaired PRC houses now look like brick houses from outside.
A house repaired under a licensed scheme should have a certificate from PRC Homes Ltd, often called a certificate of reinstatement. The warranty that came with a repair ran for ten years from completion, so on older repairs it will have expired. The certificate still matters, because it is evidence that the repair followed an approved design and was inspected. Some houses were repaired outside the licensed schemes, and some certificates have been lost. Without one, lenders may treat a house as unrepaired.
How to recognise a PRC house
- Walls made of concrete panels or slabs, often with visible joints, sometimes set between concrete columns.
- On Airey houses, horizontal concrete planks that overlap like weatherboarding.
- Rendered or painted concrete where neighbouring houses of the same age are brick.
- Groups of identical houses on an estate, often built by a council.
- In the roof space, concrete columns, beams or panels may be visible.
Repaired houses can be hard to spot. An unrepaired neighbour of the same design can show what a house was built as. The EPC may describe the walls as "system built", and the seller's papers should include any certificate.
Mortgages and insurance
Lenders set their own criteria, and they change. In general:
- most lenders will not lend on a designated PRC house that has not been repaired
- many lenders will consider a house repaired under a licensed scheme that has its certificate, sometimes with conditions
- types that were never designated may be considered case by case
Check with your lender or broker before you pay for a survey, and ask what they need to see. Tell your insurer the construction type, and ask your conveyancer to check the repair paperwork.
What we check
In a Level 3 Building Survey of a PRC house we:
- identify the system as far as a visual inspection allows, including from the roof space
- look for cracking, rust staining, spalling and bulging in any exposed concrete
- look at the quality and condition of any repair, including where new walls meet the original structure and the attached house
- note extensions or alterations fixed to the concrete structure
- ask for the repair certificate and any engineer's reports, and set out what your conveyancer should confirm
- use a drone to look at the roof and high-level details, where flight is permitted
A survey is a visual inspection. We cannot see steel inside concrete or measure how far carbonation has gone. Where that matters, we recommend a structural engineer, who can take samples and test the concrete.
What we have found locally
Our survey reports from 2022 to 2026 include Cornish Unit and Reema construction.
Reports that recorded Cornish Unit construction:
2 DBISS survey reports since 2022
Our Cornish Unit records include homes in the Abingdon-on-Thames (OX14) area. A Cornish Unit home we surveyed had been repaired and had a PRC Homes Ltd certificate of reinstatement.
Reports that recorded Reema construction:
1 DBISS survey report since 2022
The Reema construction we recorded, in the OX25 district of north Oxfordshire, was of the Conclad type. Reema Hollow Panel was on the 1984 list of types to be designated; Reema Conclad was not. It is one reason why identifying the exact system matters.
Sources
- legislation.gov.uk: Housing Act 1985, Part XVI
- Hansard: Housing Defects Bill, second reading, House of Commons, 26 April 1984
- Hansard: Prefabricated Concrete Houses (Thurrock), House of Commons, 24 February 1987
- Hansard: PRC Homes (Southampton), House of Commons, 27 January 1997
- RICS: Home Survey Standard