Buying a property is exciting — until you spot the phrase “non-standard construction” in the listing and suddenly wonder whether the house is a financial risk.
For many buyers, this term sounds alarming. In reality, it’s simply a classification used by lenders and insurers to describe homes built using materials outside traditional brick-and-tile construction. Some of the UK’s most desirable homes fall into this category, including timber-frame eco homes, steel-framed properties, concrete post-war houses, and historic thatched cottages.
Understanding what non-standard construction means is essential if you want to avoid mortgage delays, insurance issues, or costly surprises later.
Identifying the construction type is a critical part of any property inspection and valuation.
What Is Non-Standard Construction?
In UK property terms, a home is generally considered standard construction when it has:
- Brick or stone external walls
- A pitched roof covered with slates or tiles
Anything outside this definition is generally classified as non-standard construction.
This does not automatically mean the property is defective or unsafe. It simply means the building uses alternative materials or construction methods that lenders and insurers view differently.
Examples include:
- Timber frame homes
- Steel frame properties (BISF)
- Precast reinforced concrete (PRC) houses
- Modular or prefab homes
- Cob cottages
- Thatched properties
- System-built post-war housing
Because these buildings do not fit standard mortgage algorithms, buyers often require specialist surveying advice before proceeding.
Why Do Mortgage Lenders Care About Construction Type?
Mortgage lenders assess risk very carefully. Standard brick-and-tile homes are predictable in terms of:
- Longevity
- Structural performance
- Maintenance costs
- Resale value
Non-standard homes can present uncertainties around:
- Structural durability
- Availability of repair materials
- Future resale demand
- Insurance availability
As a result, some lenders may:
- Decline applications outright
- Require specialist valuations
- Request structural reports
- Reduce loan-to-value ratios
- Charge higher interest rates
- Not lend at all
Common Types of Non-Standard Construction in the UK
Timber Frame Homes
Timber frame construction is increasingly popular in modern eco housing due to excellent insulation and sustainability benefits. Older timber-framed homes are often considered higher risk by mortgage lenders, due to timber rot and decay etc.
Advantages include:
- Faster construction
- Better energy efficiency
- Lower carbon footprint
However, lenders may request additional surveys to confirm fire protection measures and structural integrity.
Steel Frame Properties
Steel-framed buildings became popular after World War II and remain common in some urban developments.
Benefits include:
- High structural strength
- Resistance to movement
- Modern architectural flexibility
Potential concerns involve corrosion protection and long-term maintenance.
Below is an example of steel-framed housing constructed during the 1940’s.
PRC (Precast Reinforced Concrete) Houses
Concrete (PRC) houses became widespread during and after both World Wars because governments needed a fast, cheap, and scalable solution to severe housing shortages.
In the UK especially, millions of homes were destroyed or damaged during wartime bombing, while returning soldiers and rapidly growing families created urgent demand for new housing. Traditional brick-built construction simply could not keep up due to shortages of:
- Skilled bricklayers
- Timber
- Steel
- Bricks
- Time
Concrete construction solved many of these problems.
Below is an example of a Wimpey No-Fines property. This type of property had concrete walls, cast in situ instead of traditional brickwork.
Some systems later developed structural defects, causing many lenders to restrict mortgages unless the property has a recognised PRC repair certificate.
Popular PRC systems include:
- Airey houses
- Cornish Units
- Reema construction
- Wimpey No-Fines
A Level 3 Building Survey is strongly recommended for these properties.
Thatched Cottages
Thatched properties are among the UK’s most charming homes, but they require specialist maintenance and insurance.
Key considerations include:
- Fire prevention measures
- Roof lifespan
- Specialist repair costs
- Mortgage lender acceptance
Many insurers will require:
- Chimney spark arrestors
- Fire-retardant treatments
- Regular maintenance inspections
Below the image of a thatched roof cottage demonstrates the complex nature of the roof structure.
Can You Get a Mortgage on a Non-Standard Construction Property?
Yes — but the process can be more complex.
Mainstream lenders rely heavily on automated valuation systems designed around standard housing stock. Non-standard properties often require manual underwriting.
Working with a specialist mortgage broker can significantly improve your chances of approval.
A broker experienced in non-standard construction can help identify lenders comfortable with:
- Timber frame properties
- Steel frame homes
- Modular housing
- PRC buildings
- Historic structures
Insurance Challenges for Non-Standard Construction Homes
Insurance providers assess rebuilding costs and risk exposure differently for non-standard properties.
Premiums may increase due to:
- Specialist materials
- Higher rebuild costs
- Fire risk
- Limited contractor availability
This is especially true for:
- Thatched roofs
- Timber structures
- Concrete prefab systems
Specialist insurers often provide better cover than comparison websites for these property types.
How to Identify Non-Standard Construction
Many buyers unknowingly view non-standard homes without realising it.
Some common signs include:
1. Visible Panel Joints
Concrete prefab homes often show faint vertical or horizontal seams externally.
2. Loft Structure
Roof spaces may reveal steel or timber framing systems.
3. Hollow External Walls
A hollow sound when tapping walls can indicate framed construction behind plasterboard.
4. Unusual Roof Designs
Flat roofs or steep pitches may indicate alternative structural methods.
If you suspect non-standard construction, arranging a detailed survey early can prevent expensive surprises later.
Why a RICS Survey Is Essential
A professional survey from a Royal Institution of Chartered Surveyors regulated surveyor is critical when buying any non-standard construction property.
A Level 3 Building Survey can help identify:
- Structural movement
- Corrosion
- Defective concrete
- Timber decay
- Roof defects
- Moisture issues
- Historical repairs
- Future maintenance liabilities
Survey findings also help buyers negotiate effectively and avoid unexpected costs.
Future Resale Value Considerations
Resale value depends heavily on:
- Structural condition
- Mortgage availability
- Insurance accessibility
- Documentation quality
Maintaining clear records of:
- Structural repairs
- PRC certificates
- Specialist maintenance
- Survey reports
can significantly improve future saleability.
Modern modular and MMC (Modern Methods of Construction) homes are also becoming more accepted by lenders as construction standards improve.
Final Thoughts
Non-standard construction should never automatically discourage buyers.
Many of these homes offer:
- Unique character
- Excellent energy efficiency
- Strong structural performance
- Competitive pricing
The key is understanding the risks, arranging the correct surveys, and working with experienced professionals.
Before purchasing any non-standard property, always:
- Confirm the construction type early
- Arrange a specialist RICS survey
- Speak with a specialist mortgage broker
- Obtain insurance quotes before exchange
With the right due diligence, non-standard properties can make excellent long-term investments.
