Selling a Non-Standard Construction House: UK Guide 2026

By Lisa Hayes · 21 October 2026

You can sell a non-standard construction house in the UK, but how easily depends almost entirely on one question: is it a "designated defective" type, and if so, does it have a valid repair certificate? Timber-frame and well-kept steel-frame homes often sell almost like any other house. An unrepaired Airey or similar precast concrete home is usually a cash-buyer sale, and the price reflects that.

What counts as a non-standard construction house?

The working definition in the trade is simple: any house not built of brick or stone with a slate or tile roof. One industry guide puts the number of such homes in the UK at around 1.5 million, and notes the Building Research Establishment (BRE) catalogued more than 500 building systems between 1919 and 1976. A great many of those were postwar attempts to put up housing quickly with whatever materials and labour were to hand.

That is a very broad church. It includes steel-framed BISF houses, Wimpey No-Fines concrete homes, precast concrete systems like Airey and Cornish Unit, timber-frame houses, thatched cottages, cob and flint cottages, large flat-roofed sections, and even some modern factory-built homes. They have almost nothing in common except that a lender's valuer has to stop and think.

The important point, and the one most sellers (and plenty of surveyors) get muddled: non-standard is not the same as defective. Most non-standard homes are perfectly mortgageable. Only specific designated types carry a legal defect label.

Which types of non-standard house are there, and how do lenders see them?

Here is a broad picture of how the main groups tend to be treated. Treat it as a map, not a promise; every lender has its own list and they change it.

Those groupings reflect published broker guidance rather than any single lender's policy. If you want the nuts and bolts of one narrow case, we have separate guides on selling a house with mundic block, RAAC concrete and thatched cottages.

Is a "defective" house the same as a non-standard house?

No, and this is where I see sellers lose the plot. "Defective" is a legal term. Following serious cracking found in Airey houses after a fire in the early 1980s, the government brought in housing defects legislation in 1984. It now sits in Part XVI of the Housing Act 1985. Under section 528, the Secretary of State can designate a class of buildings as defective "by reason of their design or construction" where values have fallen substantially because the defect became generally known.

The result was a list of designated house types, nearly all of them precast concrete. Depending on how you count (the Cornish Unit and Unity types each come in two versions), sources variously say thirty to thirty-five. The list includes Airey, Boot, Cornish Unit, Dorran, Gregory, Myton, Orlit, Reema, Stent, Unity, Wates, Wessex, Woolaway and several others. Two in-situ types, Boswell and Schindler, are on it as well.

What is not on that list: Wimpey No-Fines, BISF steel-frame houses, timber frame, thatched cottages and ordinary brick-and-block homes. BISF houses are routinely mislabelled as defective by surveyors who should know better. If a valuer has marked your house down as defective, ask them which designation they are relying on.

For what it's worth, the Scottish defective housing legislation has since been repealed, though lenders can still treat a Scottish PRC house with suspicion. If you're selling north of the border, our Scotland guide covers the different process.

What is a PRC repair certificate and why does it matter?

When local authorities ran schemes of assistance under the legislation, eligible owners could have their home repaired or, in some cases, bought back. Houses repaired to an approved standard were issued with a repair certificate, and the details went on an approved repair register. The bulk of the repairs used a licensed system run by PRC Homes Ltd, a subsidiary of the NHBC, which closed in 1996.

That certificate is the single most valuable document a designated-type owner can hold. With it, many mainstream lenders will treat the house as mortgageable. Without it, the buyer pool collapses to cash buyers and a handful of specialists.

A few traps worth knowing:

• A brick skin is not proof of repair. A house that has been wrapped in brick may look like a standard house and still have no valid certificate.
• Council "partial repairs" can fall short. Some council works did not remove all defective elements and did not produce a valid certificate. Such properties may be unmortgageable.
• You may be able to re-certify. Owners without a certificate can approach an approved PRC repair specialist; council-repaired homes may be re-inspected for a fee.

How do I find out what type of house I own?

Start with the cheap, quick routes before paying for an expert.

1. Your own paperwork. The original purchase file, Right to Buy documents, mortgage valuation and any previous survey often name the construction.
2. The title and deeds. Look for references to a developer or system name. The title register may help, though construction type rarely appears.
3. The council. Building Control records and the housing department often hold records on estates built by the local authority.
4. Neighbours. Whole streets were built to one system. A neighbour who has already had a certificate or a survey may save you weeks.
5. A structural engineer or building surveyor. If you remain unsure, pay for a specialist inspection. One broker guide puts a full structural or Level 3 survey at roughly £600 to £1,500, which is small money next to what a wrong guess can cost.

Clues you can check yourself: metal or concrete columns visible in the roof space, a flat concrete soffit, non-masonry cladding, unusually thin external walls, or no cavity.

How much does non-standard construction knock off the price?

It depends on the type and the paperwork, so anyone quoting a single figure is guessing. Two broker guides offer rough ranges, and I'd treat them as indicative rather than gospel: one suggests an unremediated PRC house or failed mundic block can lose 15% to 30% or more, while another says restricted-lending types can see discounts of 20% to 30% and sales taking six to twelve months. A well-kept timber or steel-frame home may sell close to comparable standard properties.

• Timber / good-condition steel frame small or none
• Restricted-lending types (broker guide) 20–30%
• Unremediated PRC / failed mundic (broker guide) 15–30%+

The bars show the upper end of the quoted ranges, illustrative only. Your actual outcome depends on local demand, condition and the paperwork. For a realistic starting point, try our house valuation guide and a free house valuation, then ask each valuer how they've allowed for the construction.

Can I get a mortgage on a non-standard house, and what do buyers need?

Often, yes. Broker guidance says high-street banks are the strictest, building societies are more flexible (often with named-type policies), and specialist lenders the most flexible but costlier. Expect lenders to want a bigger deposit; one broker guide quotes 15% to 25% deposits and 75% to 85% loan-to-value caps for most non-standard types.

Buyers will usually need a Level 3 building survey or structural report, not a basic HomeBuyer report. If you have one ready, you remove a fortnight of dithering from the process. Broader issues are covered in our guide to selling an unmortgageable house.

Will I be able to insure it, and does that affect a sale?

Usually, but not always on the high street. Some insurers decline non-standard homes and others charge more because repair costs are harder to predict. Thatched roofs can cost two to three times as much to insure, according to one broker guide. A buyer's lender will want buildings insurance in place at exchange, so a buyer who can't get a quote can't complete.

Practical advice: get a current insurance schedule and keep your claims history tidy. After any quote, phone the insurer and confirm full cover, as one guide sensibly recommends. A specialist broker on the BIBA register can find the right insurers. If your policy already covers the construction type, include the schedule in your sale pack.

What do I have to disclose when selling?

Everything you know that matters. The TA6 Property Information Form asks about construction, repairs and guarantees, and getting those answers wrong is not a clever tactic. See our guide to the TA6 form and to material information. Concealing a known construction issue exposes you to a misrepresentation claim, and it rarely stays hidden anyway, because the buyer's surveyor will spot it in minutes.

If you don't know the exact type, say so honestly and offer an inspection. Sellers who do this keep buyers. Sellers who get vague lose them.

What documents should I gather before listing?

Build a single "construction pack". It's the cheapest way to improve your odds.

• PRC repair certificate and any related council correspondence, if applicable
• Mundic test results (Stage 1 and 2) if the area has used block of that type
• Structural or building survey reports, old and new
• Timber treatment and remedial work guarantees
• Buildings insurance schedule and claims history
• Planning and building regulation paperwork for any extension. A missing certificate can be solved with indemnity insurance in some cases, though it won't fix a structural problem.
• If you have had insulation or retrofit work done, any PAS 2035 assessment and guarantees
• Original purchase or Right to Buy papers showing construction type

Hand this pack to your solicitor before you accept an offer. If you'd like to understand the jargon on your TA6 and surveys, the property jargon page helps.

Should I repair, certify or sell as it is?

This is the actual decision, so let me be blunt about it.

If you own a designated PRC type with no certificate, getting one can unlock a mortgage-backed buyer pool and a much better price. One broker guide suggests PRC remediation commonly costs £15,000 to £40,000 and that the uplift usually exceeds the cost. I can't verify that for your house, and prices vary by region and type, so get two or three quotes from approved specialists and a surveyor's opinion on the uplift before committing.

If repairs are impractical, or you need to move quickly, sell as it is. See our guide to selling a house as is. For other cases, such as timber or steel frames in good condition, there's often nothing to fix; your job is documentation and honest pricing.

• £600–£1,500typical Level 3 / structural report (broker guide)
• £15k–£40kPRC remediation range (broker guide)
• 10–16 weekswell-run purchase on a non-standard home (broker guide)

Which selling route suits which house?

Match the route to the type and your situation.

Quick-sale companies price in the risk, so expect an offer below open-market value. That's the trade for speed. Read our explainer on why offers come in below market value and use sell house fast if you need the whole picture. For a deeper look at hard cases, selling an unsellable house is the page to read.

How long will the sale take?

Longer than a brick semi, usually, and it pays to plan for it. A broker guide suggests a well-run purchase of a non-standard home takes roughly ten to sixteen weeks, and restricted-lending types can sit on the market for six to twelve months. The delay is rarely the legal work. It's the buyer finding a lender who'll accept the property, getting a specialist survey booked and then waiting for the valuer's sign-off.

You can shave weeks off by doing the boring things early: instruct your solicitor before you list, have the construction pack ready, and tell viewers the construction type up front so the wrong buyers filter themselves out. That last one sounds counterintuitive, but a buyer who knows from day one is far less likely to wobble after four weeks and a survey fee. If the chain breaks anyway, our chain collapse rescue guide is worth bookmarking.

Do cash buyers really pay less for non-standard houses?

Yes, generally, because they're pricing the risk the lender won't take. A cash buyer or investor buying an unrepaired designated house knows that when they come to sell, they'll face the same narrow pool you do. They also know they might need to fund a repair. So the offer reflects both the discount and the cost of the work.

That isn't automatically a bad deal for you. If you've an unrepaired PRC home, nobody is going to pay full market value for it, and a certain, quick completion has real value if you're tied to a deadline such as probate, a divorce or arrears. The mistake is accepting the first figure without comparison. Offers for the same house can vary widely, and the company at the top of a Google search isn't necessarily the one paying most. Get several written offers, check fees and completion terms, and look at the reputation of each buyer before you sign anything.

Can I alter or extend a non-standard house before I sell?

Carefully. Structural alterations to a system-built house can be riskier than in a normal cavity-wall home because you may be cutting into a load-bearing frame or panel you don't fully understand. Before any work, get an engineer's view, and keep the paperwork: building regulation sign-off, structural calculations and warranties. Work done without consents can sink a sale on its own. For a quick check on whether past works were legal, see our guide to selling a house with unfinished building work.

Insulation is the other area to watch. Cavity or external wall insulation fitted to a non-standard home without a proper assessment can create damp or hide defects, and surveyors know it. If you've had retrofit work done, include the assessment and guarantee in your pack.

What about non-standard flats and ex-council blocks?

The same logic applies, with an extra layer: the building, not just your flat, is what the lender looks at. Broker guidance notes that ex-council flats get harder to finance above the fourth floor or where deck access is involved, and that cladded blocks over 18 metres may need a satisfactory EWS1 form. If you're in that position, start with our guide to selling a flat with cladding and the main sell flat fast page.

Which house types get misunderstood most?

Three come up again and again.

Wimpey No-Fines. Poured in-situ concrete walls built without fine aggregate. The homes number in the hundreds of thousands according to one industry guide. They are not on the designated list, but individual lenders can still exclude them by name or accept them only with a clean structural report. The fix is a lender-by-lender approach with a broker, not despair.

BISF houses. Steel-framed, built in the 1940s and 1950s, with a render or cladding finish. Their reputation is worse than their record, partly because valuers confuse "steel frame" with "defective". A sound survey and evidence of any remedial work does a lot of the persuading.

Cornish Unit and Airey houses. These genuinely are designated types. Unit variants and local repair histories differ, so never assume one house on the street tells you about the one next door.

What are the common mistakes?

• Calling it "standard" on the listing. Buyers' solicitors will find out, and trust goes with it.
• Trusting a vague valuer's "defective" label. Make them name the designation.
• Relying on a Level 2 survey. A broker guide notes it is usually insufficient for non-standard homes.
• Ignoring insurance until the last minute. A buyer who can't insure can't complete.
• Chasing a bargain buyer first. The first cash offer is rarely the best one.
• Doing retrofit work without paperwork. Surveyors flag it.

What if the buyer's survey flags a problem?

Don't panic and don't argue. Ask for the report, get a structural engineer to comment, and decide whether you are negotiating on price, offering a retention, or moving on. Our guide on what happens if a survey finds problems sets out the options, and if the buyer's mortgage falls over there's a guide for that too: when a buyer's mortgage falls through.

Realistic scenarios

The repaired Airey with a certificate. You're in decent shape. Lead with the certificate, expect a modest discount at most, and use an agent who has sold PRC homes before.

The Airey with a brick skin and no paperwork. The brick skin isn't proof. Chase the council, then a specialist re-inspection. Meanwhile, line up cash buyers as a fallback.

The Wimpey No-Fines house. Not designated, but lenders differ. Get a clean structural report, check cladding and render, and ask a broker which lenders are active.

The BISF house. Often wrongly treated as defective. A survey showing the steel frame is sound can turn a nervous valuer around.

The inherited house nobody knows anything about. This is common. Our guide to selling an inherited property covers the process, and a specialist inspection is step one.

A sensible order of play

1. Identify the exact type with paperwork, council records or a surveyor.
2. Establish whether it is a designated type and whether a valid certificate exists.
3. Build your construction pack and check insurance.
4. Get two or three valuations, asking each how they allowed for the construction.
5. Decide: repair and certify, sell on the open market as is, or go for a cash route.
6. Brief your solicitor before listing.

Browse our wider guides library for neighbouring topics, from leasehold to probate.

Ready to compare your options?

If your house is non-standard and you aren't sure which route fits, compare real offers rather than guessing. It costs nothing to start a valuation, and you stay in control of whether to accept anything.

This guide is general information, not legal, financial or surveying advice. Take advice from a solicitor and a qualified surveyor on your own property.