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Non-standard construction mortgages: what counts, and how to get one
Can you get a mortgage on a non-standard construction house? In most cases, yes. Plenty of timber frame, steel frame, concrete and cob homes are mortgaged every year. What changes is how many lenders will look at it, how much deposit you may need and what paperwork the valuer wants to see. The big exception is a concrete house that is officially designated defective and has not been properly repaired and certified.
What is non-standard construction?
To a mortgage lender, a "standard" house has walls of brick or stone and a pitched roof covered in tiles or slate. Anything built another way counts as non-standard, or non-traditional, construction. That covers anything from a 1950s concrete council house to a new factory-built home or a thatched cottage.
Lenders care because the building is their security. If they are unsure how a structure will age, be insured or resell, they lend less or decline. Each lender keeps its own list of acceptable types, so a house one bank turns down can suit another.
Common types, and how lenders tend to see them
A general guide only: the lender and its valuer have the final say, and condition matters as much as type.
| Construction type | What it is | Typical lender view |
|---|---|---|
| Modern timber frame | Timber structure with an outer skin of brick, block or render. Very common in newer homes. | Usually mortgageable with mainstream lenders. Some set a build-date cut-off, such as 1970 onwards. |
| Older timber frame | Pre-war or 1940s–60s timber systems, sometimes without a masonry outer skin. | Harder. Often needs a specialist lender and a structural report. |
| Timber clad | Timber boards as the outer wall finish, usually over a timber frame. | Varies. Some lenders accept it on newer homes; others treat it as non-standard and want details of the cladding's condition and fire performance. |
| Steel frame, including BISF | Post-war steel-framed houses, often with render and sheeting upstairs. BISF homes were never designated defective. | Mortgageable with a narrower range of lenders. Condition of the steel at ground level is the key question. |
| Wimpey No-Fines and other poured concrete | Walls cast in place from concrete without fine sand. Not on the defective list. | Often mortgageable, though not with every lender. |
| Precast concrete (PRC): Airey, Cornish Unit, Reema Hollow Panel, Unity, Wates, Woolaway and others | Houses built from factory-made concrete panels or posts, many designated defective in the 1980s. | Designated types are generally unmortgageable unless repaired under an approved scheme with a valid PRC certificate. Some PRC types, such as Reema Conclad, are not designated. |
| Cob and thatch | Earth walls; reed or straw roofs. | Some mainstream lenders accept them, subject to valuation. Insurance cost is often the bigger hurdle for thatch. |
| Cross-wall | Load-bearing brick or block side walls with lightweight panels front and back, common in 1960s–70s town houses. | Mixed. Many lenders consider it, some refer it to a specialist valuer. |
| Modular and other modern methods (MMC) | Homes built largely off-site from panels or volumetric units. | Widely accepted when backed by an accreditation such as BOPAS, NHBC Accepts or LPS 2020, plus a structural warranty. |
| Large flat roofs | Felt, asphalt or membrane roofs over much of the house. | A small flat-roofed extension is rarely a problem. A mostly flat roof narrows the lender choice. |
| Spray foam insulation | Foam sprayed onto the underside of the roof, or into walls. | Can stop a mortgage altogether. See our guide to spray foam insulation and your mortgage. |
Defective PRC houses and PRC certificates
After the Second World War, councils built hundreds of thousands of homes quickly using precast reinforced concrete. By the early 1980s, engineers found that in several designs the concrete was carbonating and the steel inside was rusting, which cracks the concrete and weakens the structure.
The Housing Defects Act 1984, now Part XVI of the Housing Act 1985, allowed the government to designate named house types as defective. Owners could claim a grant for repairs or, in some cases, sell back to the council. Those assistance schemes closed to new applications decades ago.
A company called PRC Homes Ltd was set up to approve licensed repair schemes. A typical repair takes out the defective concrete parts of the walls and replaces them with new load-bearing masonry, usually brick. When the work is signed off, the property receives a certificate. PRC Homes Ltd no longer operates, and certificates for newer repairs come from qualified structural engineers working to a licensed scheme.
For a mortgage, the points that matter are:
- Unrepaired designated PRC is declined by almost every lender. Cash buyers and investors make up most of that market.
- A repaired house with a valid certificate opens up far more lenders, including some high street names.
- Semis and terraces can be caught by the neighbours. Many lenders want the whole structural block repaired, not just your half.
- Scotland is different. The Scottish Government repealed the defective designation on its twelve listed PRC types in July 2018, although lending decisions remain up to each lender.
How to tell what a house is built from
Agents do not always know, and render can make a house look traditional. Clues worth checking:
- The EPC. The wall description on the Energy Performance Certificate often says "timber frame", "system built" or "cavity wall".
- The age and history. Houses built between roughly 1945 and the late 1960s on former council estates deserve a closer look.
- The loft and walls. Concrete posts or panels in the loft, walls that sound hollow when tapped, or render with no visible brick courses are all prompts to ask more.
- The paperwork. Ask the seller for any PRC certificate, structural engineer's report, building control completion certificate or new-build warranty.
- The next-door houses. If a neighbour's house has been visibly re-bricked and yours has not, find out why.
For certainty, a surveyor can identify the system. The Building Research Establishment's reference work on non-traditional houses built between 1918 and 1975 catalogues around 450 house types and is what many surveyors use.
Getting a mortgage on a non-standard construction house
Start with the right lenders. Applying to a lender that declines the property once its valuer visits can cost you survey and legal fees, and weeks of time. Tell your adviser exactly what the house is built from before any application goes in.
Expect more questions from the valuer. A lender's valuer may ask for a structural engineer's report, a PRC certificate, details of the roof and cladding, or a specialist inspection. If they are not satisfied, they can value the property as unsuitable security, which ends that application. If the figure simply comes in lower than the price, our guide on what to do when a property is down-valued covers your options.
Be ready for a larger deposit. Some lenders cap loan-to-value lower for non-standard homes, so a bigger deposit widens your choice.
Specialist lenders fill the gaps. Where high street lenders say no, smaller building societies and specialist lenders often consider older timber frame, steel frame and repaired PRC homes. Our specialist lending page explains how we work with them.
Get your own survey. The mortgage valuation is for the lender, not you. For most non-standard homes an RICS Home Survey Level 3 is the sensible choice, because it looks at the structure and materials in depth. Read our guide to house surveys and specialist reports.
Buildings insurance
Your lender will need buildings insurance, and some mainstream insurers will not quote for thatch, cob, unrepaired PRC or some timber-clad homes. Get quotes before you commit, and describe the construction accurately, as getting it wrong can invalidate a claim. Specialist insurers cover most types, sometimes at a higher premium.
Selling a non-standard home later
A house fewer lenders will mortgage has fewer potential buyers, which can mean a longer sale or a lower price than a similar brick house nearby. Keep every certificate, report and warranty safe for your future buyer's lender.
Repairing or converting a non-standard construction house
The cost of converting an unrepaired PRC home to a mortgageable standard varies too much to quote without a survey. It depends on:
- the house type and which licensed repair scheme applies
- whether it is detached, or a semi or terrace where the neighbours may need to take part
- the condition of the existing structure, foundations and roof
- planning permission and building regulations sign-off
- the engineer's inspection and certification fees
Only certified work under a recognised scheme helps with lenders. Re-cladding without that sign-off can leave you with a large bill and a house that is still unmortgageable. Involve a structural engineer first, and check which lenders would accept the finished result before you start.
Remortgaging and equity release
If you already have a mortgage on a non-standard home, a product transfer with your current lender usually avoids a fresh valuation. Moving to a new lender means passing that lender's current criteria, which may have tightened since you bought.
Equity release providers set their own property rules too. Some accept a wide range of construction types; others exclude older timber frame, spray foam or unrepaired PRC. Equity release has long-term effects on your estate, so take regulated advice.
How Quick Mortgages can help
We are a whole-of-market broker, which includes the specialist lenders and building societies that handle most non-standard construction cases. We check which lenders accept your house type before you spend money on surveys and legal fees, and we charge no broker fees.
Frequently asked questions
Can you get a mortgage on a cob house?
Often, yes. Some mainstream lenders accept cob and more specialists will consider it. Expect the valuer to look closely at damp and any cement render, which can trap moisture in cob walls.
Is a timber frame house non-standard construction?
Technically, yes, but modern timber frame with a brick or block outer skin is so common that most lenders treat it much like a standard house. Older timber systems and fully timber-clad homes have a smaller choice of lenders.
Can I get a mortgage on a Reema house?
It depends on which Reema. Reema Hollow Panel houses are designated defective and usually need a PRC repair certificate. Later Reema Conclad houses are not designated and are acceptable to more lenders, although they are still non-standard.
Are steel frame houses mortgageable?
Many are. BISF and other steel-framed houses are not designated defective, but lenders will want to know the frame is in good condition, and some ask for a structural engineer's report.
Sources
- Housing Act 1985, Part XVI (Assistance for owners of defective housing), legislation.gov.uk
- Hansard, House of Commons debate on the Housing Defects Act 1984, 6 December 1985
- Scottish Government, Defective designation repeal: guidance, 2018
- BRE, Non-traditional houses: identifying non-traditional houses in the UK 1918–75 (AP 294)
- RICS, Home Survey Standard and description of the RICS Home Survey Level 3
- Nationwide for Intermediaries, Property and construction lending criteria
- Halifax Intermediaries, lending criteria on modern methods of construction
- UK Finance, Mortgage Lenders' Handbook for conveyancers
Correct on 17 September 2026 and may change.
Disclaimer:
This article is for general guidance purposes only and does not constitute legal, financial, or professional advice. Mortgage products and their terms can vary, and it is important to seek advice from a qualified, regulated professional who can assess your individual circumstances. Please ensure you consider your unique needs before making any financial decisions.
While every effort is made to ensure that the information provided on this blog is accurate and up-to-date, we do not guarantee its completeness or accuracy. The mortgage market can change rapidly, and the information on this blog may become outdated. We recommend verifying any information before acting on it and seeking tailored advice.
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