Specialist lender Together estimated in late July 2026 that around 1.5 million UK homes, roughly 6% of the country’s 28 million residential properties, fall outside mainstream mortgage criteria. The figure was picked up across the trade press over the following days, from mortgage titles in late July through to property titles in early August. It is worth understanding what that number is and what it is not, because the category it describes is where a large part of the discount in UK property actually lives.
Where the 1.5 million figure comes from
Start with the provenance, because it changes how much weight the number can carry. The estimate is Together’s own, and Together is a specialist lender whose business is lending on property that mainstream banks decline. Together’s own report names its inputs, Searchland property intelligence data plus government and industry datasets, but discloses no sample methodology, weighting or precise test criteria, so the figure still cannot be independently reproduced or checked.
At least six outlets carried the figure, all reporting the same lender release with the same Together executive quoted throughout, which makes it one source rather than six. The two headline numbers do not quite reconcile either: 6% of 28 million is closer to 1.68 million than to 1.5 million, and no outlet resolves which figure is the real one. That is not a reason to dismiss it. It is a reason to treat it as a directional estimate from an interested party rather than as a measured statistic, and to build any decision on the underlying criteria instead of on the headline.
The useful part is not the total. It is the categories.
What makes a property unmortgageable
Unmortgageable is not really a property attribute at all. It describes lender appetite, and appetite differs between lenders and changes over time. A property three high street banks decline may be financeable by a fourth, or by a specialist, at a different rate and loan to value.
The recurring reasons a valuer or lender says no fall into a few groups. Construction type is one, covering concrete and steel framed post war housing, some timber frame, thatch and other non standard methods. Condition is another, and it is the most common: a property with no working kitchen or no working bathroom generally fails the habitability test that standard residential lending assumes.
Tenure is a third. Lenders set minimum unexpired lease terms, and a lease that runs out too soon relative to the mortgage term is a decline regardless of how sound the building is. Location and use add a fourth, covering flats above or adjacent to commercial premises, and some high rise blocks.
The distinction that matters commercially is between defects that are curable and defects that are not. A missing kitchen is a few thousand pounds and a fortnight. A structural construction type that no lender will accept is permanent, and it caps your exit to the same cash buyer pool you bought from.
Cladding remains contested
Cladding deserves separate treatment, because it is the one area where there is genuinely no settled national rule, and where confident advice should be treated with suspicion. The Building Safety Act regime sits alongside all of it.
In July 2021 the government said EWS1 forms should not be requested for buildings below 18 metres, citing expert advice that found no systemic fire risk in those blocks. In December 2021 the RICS Independent Standards and Regulation Board reviewed the guidance and confirmed it would keep it unchanged, following consultation with lenders and conveyancers who said EWS1 remained, in their view, the only reliable way to keep property lending functioning at the time. RICS published further guidance in December 2022 on how valuers should account for agreed remediation funding and timelines, and several major lenders updated their policies in response.
The result is a patchwork. A building under 18 metres with no known external wall concerns should not normally need an EWS1, but whether a specific lender and a specific valuer take that view on a specific block is a question that can only be answered case by case. For a buyer, that means the cladding position is a due diligence item to be resolved before exchange, not after. RICS is also due to bring a second edition of this guidance into effect on 1 November 2026, revisiting the criteria for lower rise blocks, so the position should be re-checked closer to that date.
How cash buyers price the gap
None of this is a problem if you are not borrowing on completion. It is the opportunity.
When a property cannot be financed conventionally, the buyer pool shrinks to cash and to bridging. Fewer bidders on the same asset is the mechanism that produces the discount, and the discount is often far larger than the cost of curing the defect. The standard route is to buy with cash or short term finance, carry out the works that restore habitability, and then refinance onto conventional terms once the property meets standard criteria.
The arithmetic only works if two things are true. The defect has to be genuinely curable, and the cost of curing it has to be established before you commit rather than estimated afterwards. Buyers who get hurt in this part of the market are almost always the ones who priced the discount correctly and the remedial works optimistically.
What this means for property investors
Treat the 1.5 million as a signpost rather than a fact. What it points at is real: a substantial slice of UK housing sits outside conventional lending, and that stock trades at a discount driven by financeability rather than by any fault in the underlying investment.
The practical discipline is to separate the two things that buyers routinely merge, whether the property is a poor investment and whether it is simply hard to finance. They are not the same test, and the gap between them is where the return is. A sound terraced house with no bathroom is a financing problem. A flat in a block with unresolved external wall issues and no funded remediation plan is a different order of risk entirely.
Before committing, establish why the property fails lender criteria, whether that reason is curable, what curing it costs, and who your buyer is at exit. If the answer to the last question is still only cash buyers after the works, price accordingly.
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