Mortgages for Non-Standard Construction Homes
- Sep 25, 2025
- 7 min read
Updated: May 31
If your home is not built from brick or stone with a tiled or slate roof, it is classed as non-standard construction, and that one fact changes how lenders treat your mortgage. A mortgage is usually still possible, but the lender pool is smaller, the checks are heavier, and the way the case is presented matters far more than on an ordinary house.
This guide explains what counts as non-standard construction, why lenders are cautious, what you will need, and the routes that tend to work. It also links to a detailed guide for each common construction type, so you can go straight to the one that matches your property.
Key points
A mortgage is often still possible, but non-standard construction limits which lenders will consider it.
You are assessed heavily on the construction type, its durability, and how easily the property could be resold.
You may need a larger deposit, typically around 15 to 25 percent, and a specialist valuation or survey.
Specialist and intermediary-only lenders offer the most flexibility, and most of them work only through brokers.
Using a broker familiar with non-standard property significantly improves your chances of approval.
What counts as non-standard construction?
Standard construction in the UK means walls of brick or stone with a slate or tiled roof. Homes like these are seen as durable, insurable and easy to resell, so almost every lender will consider them. Anything that departs from that, in materials, roof, or method of building, is usually classed as non-standard, and is assessed with more care.
Common examples, and the guide for each
Timber or steel frame. Common in certain eras and increasingly in modern builds. See timber-frame mortgages and steel-framed (including BISF) houses.
Concrete and PRC homes. Some were defective and later repaired under recognised schemes. See Wimpey No-Fines and concrete homes, and our guide on ex-local authority properties, which are often treated similarly.
BISF steel-frame houses. A specific post-war steel design that needs the right lender. See BISF mortgages.
Spray-foam insulated roofs. Increasingly a sticking point at valuation. See spray foam insulation and your mortgage.
Cob, thatch and natural-build homes. Characterful but treated as higher risk for fire and upkeep. See cob and natural-build homes.
Flat roofs and unusual coverings. Acceptable to many lenders if a good proportion of the roof is standard and it is well maintained.
Because these types can raise durability, insurance or resale concerns, lenders apply extra scrutiny before agreeing a mortgage. The good news is that for almost every type there is a lender that understands it.
Specialist construction guides
Go straight to the guide that matches your property:
Why mortgages can be more difficult
Mortgages on non-standard homes involve more checks and sometimes stricter terms. The main issues are:
Valuations and surveys. The lender will almost always require a detailed structural survey or report confirming the property's condition.
Insurance. Specialist buildings insurance is often needed, which can cost more and must be in place before completion.
Deposit. Borrowers are frequently asked for a larger deposit, often 15 to 25 percent, to reduce the lender's risk.
A smaller lender pool. Many mainstream lenders avoid these properties entirely, leaving specialist lenders as the main route.
Resaleability. Lenders want assurance the property could be sold on the open market if needed, and unusual construction can narrow the buyer pool.
Specialist and intermediary lender options
While many mainstream lenders focus only on standard property, there are specialist, intermediary-only lenders that will consider non-standard construction. Each has its own criteria, and most can only be accessed through a broker, which is where matching the property type to the right lender makes the difference. Read more about what a specialist mortgage is and who needs one.
As a broad guide, some lenders accept a modern timber frame supported by a warranty, others accept a PRC home repaired under a recognised scheme, and many will consider eco or modular homes that meet building regulations and carry an insurance-backed warranty. The right answer depends entirely on your specific property and profile.
What you will need to provide
To apply for a mortgage on a non-standard construction home, you will usually need:
A structural or specialist survey detailing the property's condition.
Any warranties or guarantees for repairs or upgrades already carried out, such as PRC repairs or a new roof.
Evidence of recent improvements, for example insulation upgrades or damp-proofing.
Proof of stable income and a good credit history to reassure the lender.
A larger deposit, which demonstrates commitment and reduces the lender's risk.
Your options
Depending on your situation, the usual routes are:
Specialist non-standard construction mortgages arranged through broker-only lenders.
Remortgaging once essential repairs or upgrades are complete.
A product transfer with your current lender if their criteria are met. See product transfer or remortgage.
Buy-to-let mortgages for rental properties, although usually on stricter terms.
Conditional offers, where funds are released once remedial works are finished.
Deposit, rates and what to expect
Expect terms to be a little tighter than on a standard home. A larger deposit, often 15 to 25 percent, is common, and rates can sit slightly above mainstream deals to reflect the added risk. The gap is frequently smaller than people fear, and it narrows as your deposit grows and as you provide a clean survey and warranties. Timescales can be longer where a specialist valuation is needed, so it is worth starting early.
How appetite varies by region
Which lenders will consider a property, and on what terms, can vary with where it is and how common the construction type is locally:
South West and rural areas. Thatched cottages and cob houses are more common, especially across Devon and Somerset, and lenders lean heavily on a specialist survey.
Midlands and the North. Post-war PRC homes and prefabs appear more often. Many that have been repaired under an official scheme are treated as mortgageable.
Urban areas. Modern modular and eco-build homes are increasingly seen in regeneration schemes and tend to attract younger buyers and a growing set of lenders.
A typical case
A buyer in Bristol looking at a 1960s timber-frame house might need a structural survey confirming the frame is sound, plus a deposit of around 20 percent. With both in place, some specialist lenders can offer terms close to those on a standard home.
What has changed recently
Non-standard construction has become a little easier to finance over the past year. More lenders now publish clear criteria for these property types, specialist insurance is easier to arrange, and demand for character and rural homes has grown. The main new hurdle is energy efficiency: tightening regulations mean some properties need upgrades before they are considered mortgage-ready, so it is worth factoring that into your plans.
Expert tips and common mistakes
Tips
Work with a broker experienced in non-standard construction.
Arrange a full structural survey before you apply, not after.
Carry out essential repairs early to widen your lender options.
Keep all guarantees, certificates and repair documents together and ready.
Look at local demand and resale values, not just the purchase price.
Common mistakes
Assuming every lender accepts non-standard construction. Many do not.
Ignoring extra costs such as a specialist survey or higher insurance.
Expecting a high loan-to-value. Lower LTVs are more common on these homes.
Focusing only on rate rather than lender flexibility and conditions.
Holding back known issues, which usually delays or stops the application.
Final thoughts
Non-standard construction homes can be rewarding to own and live in, but they need a more careful approach to the mortgage. The options exist, they are simply found through specialist, broker-only channels, and success usually comes down to presenting the property and your finances clearly. At Manor Mortgages we work with clients across every construction type, help them understand the criteria, and prepare a strong application. If you are buying or remortgaging a non-standard home, we can review your case and explain your options.
Frequently asked questions
What counts as a non-standard construction home in the UK?
Any home not built with brick or stone walls and a tiled or slate roof. That includes timber frame, steel frame, prefabricated or concrete-panel houses, thatched cottages, cob homes and many listed buildings made with unusual materials.
Can I get a mortgage on a concrete or prefab house?
Often, yes, but it depends on the property's condition and whether repairs or upgrades have been carried out. Specialist lenders will consider concrete or prefab homes, especially where structural certificates or repair guarantees are available.
Do I need a bigger deposit for a non-standard construction mortgage?
Usually. Many lenders ask for 15 to 20 percent or more to offset the perceived risk. The exact figure depends on the property type and the lender's criteria.
Will my interest rate be higher on a non-standard property?
It can be, because fewer lenders compete and the risk is seen as greater. A broker helps compare specialist products to find a competitive option for your circumstances.
What surveys are needed for a non-standard construction home?
A specialist survey is usually required, for example a structural report on a timber or steel frame, or a roof report on a thatched property. These give the lender confidence the home is safe and insurable.
Can I remortgage a non-standard construction property?
Frequently, yes, particularly once improvements have been made. Some borrowers use a product transfer with their current lender, which can be simpler than a full new application.
Are non-standard construction homes harder to sell?
They can be, because fewer lenders accept them, which narrows the buyer pool. That said, character homes such as listed cottages or modern eco homes often attract strong demand in the right markets.
Written by Ben Stephenson, CeMAP-qualified mortgage broker, and reviewed by the Manor Mortgages team.
Manor Mortgages is FCA authorised (496907), has been trading for nearly 30 years and is rated 4.9 on Google. We are Bristol-based mortgage brokers and assist clients nationwide.