What Makes an Auction Property Unmortgageable?

Why lenders care: A leasehold property loses value as the lease shortens. Below 80 years, the cost of extending the lease rises sharply (due to the "marriage value" calculation under the Leasehold Reform Act). Most lenders will not offer a standard mortgage if the lease falls below 70–85 years remaining at the start of the mortgage term — and some require it to run at least 70 years beyond the end of the mortgage term.

In practice, a flat with 74 years on the lease that you plan to hold for 25 years may be declined by most lenders, leaving you with bridging finance as your only option until the lease is extended.

Why lenders care: An increasing number of UK mortgage lenders are restricting lending on properties with an Energy Performance Certificate (EPC) rating of F or G. Under proposed Minimum Energy Efficiency Standards (MEES) regulations, landlords in England and Wales may be required to achieve at least an EPC C rating for new tenancies. Several lenders now either decline outright on F/G properties or require a "green improvement" plan as a condition of the mortgage.

A property with no EPC at all — common at auction — is treated with equal caution by many lenders, as the energy efficiency is unknown.

Why lenders care: A mortgage is secured against the property. If the property is structurally unsound, the lender has no adequate security. Properties with active subsidence, severe damp, major roof failure, or extensive structural cracking are typically classed as uninhabitable — and standard lenders will not lend on uninhabitable property.

Non-standard construction is a separate but related issue. Properties built from concrete panels (Reema, Airey, BISF, Wimpey No-Fines), timber frame, steel frame, or certain prefabricated systems are declined by most high-street lenders outright. They are not necessarily structurally unsafe — but their resale market is limited and valuation is less certain.

Why lenders care: Restrictive covenants are obligations that run with the land and bind every future owner. Most are harmless (e.g. "no caravans on the driveway"). However, some covenants can severely restrict what you can do with the property, limit its value, or even expose you to financial liability if breached.

Lenders take particular note of covenants that: restrict the property to a single residential dwelling (blocking HMO conversion), prohibit subletting, impose obligations to maintain shared areas, or contain financial contributions that are uncapped. If the covenant creates uncertainty about the lender's security, they will decline or require indemnity insurance as a condition of the mortgage.

Why lenders care: Absolute title is the gold standard — it means the Land Registry has verified and guaranteed the ownership chain. Possessory title means the seller cannot prove how they came to own the property (common with adverse possession claims or very old unregistered land). Qualified title means there is a known defect in the ownership chain.

Most mortgage lenders will not lend against possessory or qualified title without indemnity insurance, and even then, some will decline outright. If the seller offers the property with "no title guarantee" in the special conditions, this is a major red flag — they are explicitly disclosing that they cannot guarantee their right to sell.

Why lenders care: Japanese knotweed (Fallopia japonica) is an invasive plant capable of penetrating building foundations, drains, and concrete. Its presence within 7 metres of a property is considered a significant risk by most UK mortgage lenders. Without a professional treatment and management plan in place, most lenders will decline to mortgage a property where knotweed is present or recently recorded.

Many lenders use RICS Knotweed Categories (A–D). Category A and B (active growth close to the property) typically result in decline. Categories C and D (distant or managed) may be acceptable with a valid treatment plan and an insurance-backed guarantee (IBG) in place, typically for a 10-year period.

Why lenders care: A flying freehold occurs when part of a freehold property overhangs or underlies another freehold property — for example, a Victorian terrace where part of the first floor extends over a neighbouring property, or a room above a shared passageway. Unlike a flat (which has a lease providing reciprocal obligations), flying freeholds have no automatic legal mechanism to compel the neighbouring owner to maintain the shared area.

If the neighbour lets their property deteriorate and it damages yours, you may have limited legal recourse without expensive litigation. Most high-street lenders will decline flying freeholds that exceed 10–15% of the property's floor area, or where the flying freehold covers a structural element (e.g. the roof, load-bearing walls).

Why lenders care: Most standard residential lenders will not mortgage a flat above a commercial premises. Their concern is dual: the commercial use affects the residential amenity and value, and the mixed-use nature of the building creates complications for buildings insurance and lease enforcement. The type of commercial use matters significantly.

Flats above a restaurant, takeaway, nightclub, or betting shop are typically declined outright. Flats above a solicitors' office or estate agent may be acceptable to some lenders. Flats above a pharmacy or dentist are often borderline. The closer the commercial use is to food preparation, alcohol, or late-night activity, the harder it is to mortgage.

Why lenders care: Building regulations approval confirms that structural works (extensions, conversions, new electrical installations, new boilers) were carried out safely and to the required standard. Without a completion certificate, the lender (and any future buyer) has no independent confirmation the works are safe.

Works carried out after November 1985 require building regulations approval. Missing certificates are extremely common at auction — properties are often sold because the original owner died or the estate is being wound up, and paperwork was never located. Most lenders will accept indemnity insurance as a substitute, provided the works appear visually sound and the local authority has not taken enforcement action.