What counts as non-standard construction
Standard construction in the UK means cavity walls of brick or stone with a pitched, slate or tiled roof. Anything that departs from that, in walls, roof or overall method, is broadly classed as non-standard. The label covers a huge spread, from charming period cob cottages and timber-framed homes to mass-produced post-war concrete and steel-framed houses built to tackle housing shortages.
The reason it matters is risk. Some non-standard types have a strong track record and are mortgageable with mainstream lenders, while others, particularly certain precast reinforced concrete (PRC) designs, were found to be structurally defective and were formally designated under the Housing Act 1985. Those can be very hard to mortgage unless repaired under an approved scheme with the right certification.
Even where the construction is sound, lenders worry about how easily the property can be valued, repaired and resold. That caution shows up as smaller loan-to-value limits, fewer lenders, higher rates, or a requirement for a specialist structural report.
Check mortgageability before you offer
Some non-standard homes, especially designated defective concrete types, are very hard to mortgage without an approved repair and certificate. Speak to a broker and confirm finance is realistic before you commit to a purchase.
Common non-standard construction types
Each type carries a different level of lender and insurer caution.
| Type | Description | Typical lending view |
|---|---|---|
| Timber frame | Load-bearing timber structure, often brick-clad | Often acceptable to mainstream lenders |
| Steel frame | Steel skeleton, post-war and modern | Mixed, depends on type and condition |
| PRC concrete | Precast reinforced concrete panels | Often restricted, may need approved repair |
| Cob / clay | Traditional earth and straw walls | Specialist lenders, condition-dependent |
| Thatch | Thatched roof rather than tile or slate | Mortgageable but higher insurance |
| Prefab / system built | Factory-built or system designs | Case by case, survey-dependent |
Risks and considerations
- Fewer lenders, lower loan-to-value, and sometimes higher mortgage rates.
- Higher buildings insurance premiums for some types, such as thatch.
- Specialist repairs that can be costly and need particular trades.
- Resale can be slower if buyers face the same finance hurdles.
- Designated defective concrete may need an approved repair and certificate.
How to assess a non-standard home
Identify the construction type
Ask the agent and check the listing, then confirm with a surveyor.
Talk to a mortgage broker
Establish which lenders will consider the type and on what terms.
Commission a specialist survey
Use a surveyor experienced in that construction for a Level 3 report.
Check for repair certificates
For concrete types, look for an approved PRC repair scheme certificate.
Get insurance quotes
Confirm buildings cover is available and at what premium before exchange.
Factor resale into your plans
Consider how easily the next buyer could finance the same property.