Home Insurance · UK Research · 2026

Non-standard construction home insurance.

If your home isn’t brick walls under a tiled or slate roof, most price-comparison quotes will simply refuse it. Here’s what counts as non-standard construction in 2026, which types the market finds hardest, and how cover is actually arranged.

What counts as non-standard Home insurance hub

Quick answer

The essentials in 30 seconds

“Standard construction” means brick or stone walls with a tiled or slate roof. Anything else — thatch, timber frame, concrete or steel frame, prefab, cob, flat roof — is non-standard.
It’s insurable, but usually not on a comparison site. Cover generally comes from specialist insurers and brokers who underwrite the property individually.
Premiums are higher, and thatch is in a class of its own. Broker index data reported in 2026 put average thatched buildings-and-contents premiums at roughly four times their 2022 level.
Rebuild cost is the number that matters. Non-standard materials and trades cost more to reinstate, so a professional reinstatement cost assessment is worth far more than a rough guess.

General guidance drawn from ABI, BIBA and RICS material and UK trade-press reporting. Information only — not a quote and not advice.

The categories

What counts as non-standard construction

Insurers use “standard construction” as a shorthand for the risk profile they price by default: masonry walls, a pitched tile or slate roof, no unusual materials. Step outside that and the fire, water-ingress, subsidence or reinstatement-cost profile changes, so the property has to be looked at on its own terms. The table below covers the types the UK market sees most often.

Construction type	Why insurers treat it differently	Difficulty in 2026
Thatched roof	Fire risk and reinstatement cost — a re-thatch is a specialist trade, and fire claims are frequently total losses	Hardest — a shrinking panel of insurers
Timber frame	Fire spread and, on older frames, rot and infestation; modern timber frame is often treated far more normally than owners expect	Moderate — widely available via specialists
Concrete, steel frame and PRC prefab	Post-war prefabricated reinforced concrete types were designated defective under the Housing Defects Act 1984; mortgageability and repair status drive the decision	Harder — depends heavily on whether the property has been structurally repaired
Cob, clay lump and earth walls	Water ingress and erosion; repairs need lime-based and traditional materials, not modern equivalents	Moderate to hard — heritage specialists
Flat or felt roof (over roughly a quarter of the roof)	Shorter lifespan and a higher leak frequency, so insurers ask about age, material and last renewal	Common and usually straightforward to place
Listed buildings	Consent rules mean repairs must use matching materials and methods, pushing reinstatement costs well above market value	Moderate — needs a properly assessed sum insured
Eco, straw-bale and SIPs homes	Limited claims history for underwriters to price against, plus specialist repair supply chains	Moderate — a growing specialist niche
Mundic block (Cornwall and west Devon)	Aggregate degradation in some pre-1950s concrete; the Mundic block grading affects both lending and cover	Regional and grade-dependent

Indicative categorisation for orientation only. Every insurer defines “non-standard” slightly differently — always answer their construction questions exactly as asked.

What it costs

Premiums, and why thatch is the outlier

There is no single non-standard rate. A modern timber-frame house may be priced close to a comparable brick one; a Grade II thatched cottage is a different market entirely. The clearest published movement is in thatch: UK trade press reporting in 2026 cited broker index data showing average combined buildings-and-contents premiums for thatched homes rising from roughly £600 in 2022 to around £2,400 in early 2026 — a rise of more than 300% in four years — as claims costs climbed and several insurers stepped back from the segment. Other non-standard types have seen nothing like that.

What drives your price	What underwriters are actually looking at
Rebuild (reinstatement) cost	The single biggest factor. Specialist materials and trades mean rebuild cost often bears little relation to market value
Construction type and age	A 1990s timber frame and a 400-year-old cob cottage sit at opposite ends of the same “non-standard” label
Condition and maintenance	Roof age, last re-thatch or felt renewal, damp history, and any structural repair certificates
Risk mitigation	For thatch: chimney lining, spark arrestors, sweeping records, fire-retardant barriers, smoke detection
Listing and consent status	Listed status raises reinstatement cost because repairs must match original materials and methods
Claims and flood/subsidence history	Priced as it would be on any home, but with less competition to soften the loading

Indicative directions only — not quotes and not stated averages. Non-standard property is underwritten case by case.

Getting covered

How cover is arranged in practice

Go to a specialist, not a comparison engine. Automated quote engines screen out declared non-standard construction on a database flag. Specialist insurers and brokers assess the building itself.
Get a reinstatement cost assessment. A chartered surveyor with experience of your construction type will produce a defensible sum insured. Guessing is the most common cause of underinsurance, and underinsurance can see a claim settled proportionally.
Declare the construction precisely. Wall material, roof material, the percentage of roof that is flat, listing grade and any known defect designation are all material facts. Getting a loaded quote is far better than an unenforceable one.
Gather your paperwork first. Re-thatch and chimney-sweep certificates, electrical and structural reports, PRC repair certificates and Mundic grading reports all make a case easier to place.
Expect conditions, not just a price. Non-standard policies often carry maintenance warranties — annual chimney sweeping, for example. Breaching them can affect a claim.

If your property also has a movement history, the same specialist-market logic applies — see our guide to insuring a house with a history of subsidence. For how buildings and contents cover fits together generally, see buildings and contents home insurance or the home insurance hub.

Common questions

Non-standard construction insurance FAQs

What is classed as non-standard construction?

Anything outside brick or stone walls with a tiled or slate pitched roof. In practice that means thatch, timber frame, concrete or steel frame, prefabricated reinforced concrete, cob and clay lump, straw bale and other eco builds, and homes with a large proportion of flat or felt roof. Listed buildings are usually handled by the same specialist market even where the materials themselves are conventional.

Can I get non-standard construction home insurance on a comparison site?

Usually not, or not on sensible terms. Comparison engines are built around standard-construction risk and tend to decline or exclude once non-standard construction is declared. Cover generally comes from specialist insurers and brokers who look at the individual property, its condition and its reinstatement cost rather than a database category.

Why has thatched home insurance become so expensive?

Fire claims on thatched properties are often total losses, and the cost of re-thatching and of heritage-standard rebuilding has risen sharply. UK trade press in 2026 reported broker index data showing average thatched buildings-and-contents premiums roughly quadrupling since 2022, alongside insurers withdrawing from the segment, which leaves less competition to hold prices down. Documented fire mitigation — lined chimneys, spark arrestors, regular sweeping, smoke detection — is what owners can most directly influence.

Is timber frame treated as non-standard?

Technically yes, but it is one of the easier types to place. Many modern timber-frame homes with a brick outer skin are priced close to equivalent masonry properties. Older or exposed timber frames attract more scrutiny because of fire spread, rot and infestation risk. Either way the construction must be declared accurately — insurers ask specifically about wall type.

How do I work out the rebuild cost for a non-standard home?

Commission a reinstatement cost assessment from a chartered surveyor experienced in your construction type. Online rebuild calculators are built around standard construction and can understate a thatched, listed or heritage property substantially. Because underinsurance can lead to a claim being scaled back proportionally, an accurate sum insured matters as much as the premium.

Can you insure a prefab or PRC concrete house?

Often yes, though it depends on the type and its repair status. A number of post-war prefabricated reinforced concrete house types were designated defective under the Housing Defects Act 1984. Where a property has been structurally repaired to an approved scheme and certified, both insurance and mortgage lending become considerably easier; where it has not, the pool of insurers and lenders narrows.

Does a flat roof make my home non-standard?

Only once it makes up a meaningful share of the roof — many insurers ask whether more than a quarter of the roof is flat. A small flat-roofed extension is generally unremarkable. Where the proportion is higher, insurers will ask about the covering material, its age and when it was last renewed, since flat roofs have a shorter life and leak more often than pitched ones.

What happens if I don’t declare non-standard construction?

Construction type is a material fact. If it is misdeclared, an insurer may reduce a claim payment, or void the policy altogether where the misrepresentation was deliberate or reckless. A policy bought on inaccurate information may be worth very little at the point you need it, so it is always better to declare the construction fully and pay the correct price.

Information only — not financial advice. Figures are indicative and for orientation, not quotes or stated averages, and non-standard property is underwritten on each building individually. My Insurance Expert is not an FCA-authorised intermediary and does not arrange or sell policies. Last updated: 2026-07-18

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