Non-standard construction and which houses lenders refuse

Lenders do not refuse non-standard construction as a whole. They refuse particular construction types, and each lender publishes its own list. This guide looks at what two lenders’ published criteria say, how houses designated defective under the Housing Act 1985 fit in, and why the repair status of the house next door can matter as much as your own.

The types that get refused outright

Aldermore’s property and valuation policy guide for brokers, dated September 2026, lists the property types it will not accept. They include properties with cob walls, pre-fabricated properties, precast reinforced concrete properties that have not been suitably repaired, steel-framed houses built before 1987 and 100% timber properties. It says large panel system construction is not acceptable, and that PRC flats and maisonettes are unacceptable in all circumstances.

Other lenders draw the line elsewhere. The Mortgage Lender’s residential property criteria for professional intermediaries, dated June 2026, list steel framed construction as unacceptable unless it is modern purpose built flats. They also list large panel system flats and maisonettes as unacceptable, although houses and maisonettes of not more than two storeys are acceptable subject to a satisfactory report from a structural engineer. Check the criteria of the lender your broker is using rather than assuming one list applies to all.

Houses designated defective in law

A harder category sits above lending criteria. Under section 528 of the Housing Act 1985, the Secretary of State can designate a class of buildings as defective if the buildings in the class are defective by reason of their design or construction and, because that has become generally known, the value of some or all of the dwellings has been substantially reduced. Notice of a designation is published in the London Gazette.

Designated classes include precast reinforced concrete house types, the Airey house among them. Whether a particular house falls in a designated class, and what has been done to it since, depends on the property, so take your solicitor’s advice on the house in front of you rather than on the type.

One provision is worth knowing before you view a council-owned example. Under section 563 of the Act, a public sector authority selling a defective dwelling must give the buyer written notice before the disposal specifying the qualifying defect. Where the buyer has not been given that notice before contracting, the authority must give a further notice before it conveys. The buyer is then not obliged to complete for six months from service of that notice and may withdraw within that period by written notice, with any deposit repaid.

What a PRC certificate actually buys

Precast reinforced concrete, usually shortened to PRC, covers many homes built after the Second World War, when traditional materials and skilled labour were in short supply. BRE says tens of thousands still remain and that structural repairs are needed because of the effect of concrete carbonation. Its certification scheme, which issued its first certificate in July 2016, covers repairs by registered practitioners to the Airey, Reema, Underdown/Winget and Wates types, and keeps a register of repaired properties for lenders to use. Repairs before that date were made under the PRC Homes scheme run by PRC Homes Ltd, a subsidiary of the NHBC.

Lenders want proof of the repair, and some want it for the neighbours as well. Aldermore says PRC homes are acceptable if they have been repaired in accordance with a registered PRC scheme, and that adjoining properties must also have been correctly repaired. The Mortgage Lender asks for repair under the PRC Homes Ltd guarantee scheme for properties listed under the Housing Defects Act, including the subject property and all adjoining properties in the structural block. Buy a properly repaired half of a semi that is attached to an unrepaired half and a lender with rules like these can still refuse.

That is the trap many buyers walk into, because your mortgage can depend on what your neighbour did. The repair itself needs checking too. In a 2025 Financial Ombudsman Service decision, Barclays’ policy was that it would not approve a mortgage on a PRC property unless it could be shown the house had been repaired under a licensed scheme with all PRC elements removed. The engineer’s report in that case said the local authority had renovated the property but the precast concrete components had not been removed. A sale agreed at £353,000 in 2024 did not go ahead, and the house later sold for £210,000. The ombudsman awarded the owners £500 because Barclays had not followed up its valuer’s PRC warning, but did not hold the bank responsible for the loss, since buying the house was the owners’ decision and they could have commissioned a survey.

Steel frame, timber frame, cob and single skin

Steel frame depends on the lender. At Aldermore, steel framed houses built before 1987 are unacceptable, while steel framed properties built after 1987 are acceptable with BBA or WIMLAS certification. The Mortgage Lender treats steel framed construction as unacceptable unless it is modern purpose built flats.

Timber frame is more widely accepted. Aldermore accepts timber framed properties with a masonry or non masonry outer skin, but says 100% timber properties, and timber framed properties clad with timber, are unacceptable. The Mortgage Lender excludes 100% timber construction unless it is of high standard and in a location where there is a proven, sustainable demand.

Cob is on Aldermore’s unacceptable list. On single skin walls, Aldermore lists properties with an element of single skin among its non-standard types and prohibits 100% single skin, and The Mortgage Lender excludes single leaf brick offshoots and extensions unless the single skin element relates to a non-habitable room.

The resale consequence

BRE says mortgage lenders show a reluctance to lend on PRC properties, and a certificate answers part of that. It helps, but a future buyer who needs a mortgage from a lender with rules like these will need the same paperwork you did, so keep the repair certificate and the engineer’s report with the deeds.

Before you offer, ask the agent for the repair certificate, the engineer’s report and the equivalent documents for the properties either side, and send them to a broker before you pay for a survey. Our guide to what makes a property unmortgageable explains the wider picture, and our comparison of a survey and a mortgage valuation shows why a lender’s valuer is not checking the same things as your surveyor. Lenders can also refuse for legal reasons, as our guide to flying freehold shows. If you are buying one, compare conveyancing quotes from firms that have handled a PRC repair file before. If you are buying one, compare conveyancing quotes from firms that have handled a PRC repair file before.