Non-Standard Construction: Surveying Unusual Homes

When most people picture a British home, they think of brick walls, a tiled roof, and timber floor joists - the kind of tried-and-tested construction that has been used for well over a century. But a significant number of properties across the UK were built using very different methods and materials, and these are collectively known as non-standard construction.

In simple terms, non-standard construction refers to any property that deviates from the conventional brick-and-block build with a pitched, tiled or slated roof. This includes homes with prefabricated concrete panels, steel frames, timber frames, in-situ poured concrete, and a range of other systems - many of which were introduced during or after the Second World War to address an urgent need for housing. If you are buying, selling, or planning works on one of these properties, understanding what you are dealing with is essential.

Common Types of Non-Standard Construction

There is no single definition of a non-standard property, but the following construction types are among the most commonly encountered across the North of England and Wales.

Prefabricated Reinforced Concrete (PRC) homes were mass-produced from the 1940s onwards to address the post-war housing shortage. Types such as Airey, Wimpey No-Fines, Reema, and Unity are still widely found today. Many were later designated as defective under the Housing Defects Act 1984, meaning they carry specific legal and mortgage implications.

Steel-framed properties, including Dorlonco and Atholl houses, feature a structural steel skeleton with varied external cladding. The frames themselves are generally robust, but corrosion of hidden steelwork can be a significant long-term concern.

Timber-framed construction covers everything from older vernacular buildings to modern closed-panel systems. Older timber frames can suffer from rot and insect infestation, whilst modern systems can be problematic if moisture vapour barriers have been compromised.

In-situ concrete systems, such as Wates and Cornish Unit, involve concrete poured on site rather than factory-made panels. Carbonation and reinforcement corrosion are common issues in older examples, and both can be difficult to detect without a thorough inspection.

Timber and stud-frame clad properties, where a lightweight frame is clad in render, wood, or fibrous cement boarding, are also considered non-standard, particularly where performance or durability falls short of modern expectations.

Why Do Non-Standard Properties Require Specialist Surveys?

A standard visual inspection will not go far enough when you are purchasing a non-standard construction property. These homes present a unique set of risks that require a surveyor with specific knowledge of the construction type, its known defects, and the implications for maintenance, repair, and future value.

The RICS Level 3 Building Survey is the most appropriate starting point for any non-standard property. Unlike the Level 2 Homebuyer Report, which suits conventional homes in reasonable condition, a Level 3 survey provides a detailed assessment of the building's construction, condition, and defects. It gives you the information you need to make a fully informed decision, including a realistic picture of remediation costs and the likely impact on insurability and mortgage availability.

In many cases, a structural inspection will also be required. Where a property has PRC construction, for example, a specialist PRC report may be needed alongside the building survey to determine whether the structure meets the requirements for an NHBC PRC Homes Ltd certificate. Without this, obtaining a mortgage is extremely difficult.

At AMS Surveys, our RICS Chartered Surveyors have hands-on experience with a wide range of non-standard construction types. We can advise on the most appropriate survey approach for the property you are considering, giving you honest, impartial guidance from the outset.

The Risks Associated With Non-Standard Construction

The risks vary considerably depending on the construction type, age of the building, and any repairs or upgrades already carried out. However, several concerns recur frequently.

Structural deterioration is a primary concern with many PRC and concrete systems. Carbonation, where carbon dioxide penetrates the concrete and causes steel reinforcement to corrode, can lead to spalling, cracking, and in severe cases, loss of structural integrity. This process is often concealed behind internal or external finishes and can go undetected for years.

Moisture ingress and dampness are common where the original design relied on an outer skin of cladding or render to keep water out. If that skin becomes compromised, water can penetrate the structure rapidly. Our damp and timber surveys are an important part of any assessment, identifying moisture pathways that may not be visible to the untrained eye.

Mortgage and insurance availability is a practical concern that often catches buyers off guard. Many high-street lenders will decline to mortgage a non-standard construction property without specialist survey evidence or confirmed approved repairs. Buildings insurance can also be more expensive or harder to arrange, so knowing this early in the purchasing process can save considerable time and money.

How a Survey Protects Buyers and Lenders

For buyers, a specialist survey provides clarity. Rather than discovering structural problems after moving in, at which point the financial consequences can be severe, you gain a full picture of the property's condition before you commit. That information gives you real negotiating power, whether you decide to proceed, renegotiate the price, or walk away.

For lenders, a mortgage valuation alone is not sufficient for a non-standard property. Most will require a full building survey and, in some cases, a specialist structural report before releasing funds. Our structural surveys are prepared by RICS Chartered Surveyors who understand both the technical and commercial dimensions of non-standard construction, producing clear reports that lenders accept with confidence.

If you already own a non-standard home and are considering extending or converting it, specialist advice is equally important. Our architectural design services, including house extensions and loft conversions, are designed with these complexities in mind. If the cost of extension works is a concern, speaking to our building consultants early means you can plan realistically and avoid costly surprises further down the line.

Frequently Asked Questions About Non-Standard Construction

Can I get a mortgage on a non-standard construction property? Yes, in many cases, but it depends on the construction type and condition. Some lenders require a specialist survey, structural report, or confirmation of approved repairs. PRC properties in particular can be difficult to mortgage unless repaired under an approved scheme with an NHBC PRC Homes Ltd certificate. Speaking to a specialist surveyor before making an offer will clarify what lenders are likely to require.

Is non-standard construction always a problem? Not necessarily. Many non-standard properties are well-maintained and remain in good structural condition. The key is having the right information, which means commissioning a thorough survey from a qualified professional rather than relying on a basic mortgage valuation.

What is the difference between a Level 2 and Level 3 survey for a non-standard property? A Level 2 Homebuyer Report is suited to conventional properties in reasonable condition. A Level 3 Building Survey goes considerably further, providing a detailed assessment of construction, condition, and defects. It is strongly recommended for any non-standard property, and for some construction types, an additional structural report will be needed alongside it.

What happens if defects are found? Defects do not automatically mean you should walk away. A clear picture of remediation costs gives you a basis to renegotiate the purchase price, request that the vendor carry out repairs before completion, or budget accurately for works after moving in. Your surveyor can advise on the most appropriate course of action based on the specific findings.

Speak to a Specialist Before You Commit

Buying a non-standard construction property without specialist surveying support is one of the most common and most avoidable mistakes that property buyers make. The risks are real, but they are entirely manageable when you have the right advice from the start.

Whether you are a first-time buyer, an investor, or an existing owner planning future works, our team is here to help. Get in touch with us today to find out how we can support you.