Written by Callum Lyman AssocRICS, Director, Surveyor and RICS Registered Valuer at Lyman Marshall Chartered Surveyors. Published 15 September 2026 · Updated 15 September 2026
The RICS professional standard on reinstatement cost assessment is blunt about how often the figure should be looked at: the sum insured needs an annual adjustment for inflation and a major review and reassessment every three years, or sooner if the building has been altered. Most buildings insurance policies we see have never had either.
That is the whole problem in one sentence. A reinstatement cost assessment is not a document you commission once and file. It is a number with a shelf life, and the gap between the figure on the schedule and the cost of actually rebuilding usually opens up quietly, over renewals nobody reads closely.
Quick answer: A reinstatement cost assessment is a surveyor’s calculation of what it would cost to rebuild a property from scratch after a total loss, including demolition, debris removal, professional fees and statutory costs. It sets the buildings sum insured. It is not the market value and it is not what you paid.
What a reinstatement cost assessment actually is
A reinstatement cost assessment answers a hypothetical question: if this building were destroyed tomorrow, what would it cost to put it back?
The surveyor measures the building, records its construction, and prices the rebuild using published construction cost data adjusted for the specific property — its age, its materials, its access, its planning constraints. The result is a figure the insurer uses to set the sum insured, and the ceiling on what they will pay when a claim lands.
The word “reinstatement” is doing a lot of work there. It means putting the building back as it was, to the same standard, in the same materials, to current building regulations. For a 1990s detached house that is largely a pricing exercise. For a stone cottage with a Collyweston slate roof it is a very different calculation, and one that no online calculator is designed to make.
Why the rebuild figure has nothing to do with the market value
This is the single most common misunderstanding, and it costs people money in both directions.
The RICS standard states it plainly: the declared value for insurance purposes has no direct relationship to the market value of the property. Market value includes the land. Reinstatement cost does not — the plot survives the fire. Market value reflects demand, location and what a buyer will pay. Reinstatement cost reflects bricks, labour, scaffolding and fees.
| Situation | Typical relationship |
|---|---|
| Modern estate house in a high-demand village | Rebuild cost often well below market value — the land is much of the price |
| Period or listed property in a modest location | Rebuild cost can exceed market value — materials and craft skills are expensive |
| Non-standard construction (concrete, steel frame, timber frame) | No reliable rule of thumb — needs an individual assessment |
| Flat or maisonette in a block | Usually insured under a block policy on a whole-building assessment |
Insuring a building for its market value is therefore not a cautious choice. It is simply a different number that happens to be easier to find.
The costs most sums insured quietly leave out
When we compare a client’s schedule against a properly built assessment, the shortfall is rarely in the brickwork. It is in everything that sits around the rebuild.
- Demolition and debris removal. Before anything is rebuilt, what is left has to come down and go away, and disposal costs rise sharply where deleterious materials are present.
- Professional and statutory fees. Architect, surveyor, engineer, building control and planning input. The RICS standard notes that fees for reinstating damage are often higher than for procuring a new building.
- Site constraints. A terraced house on a narrow street needs the party walls shoring up and offers nowhere to stand a crane. That is a real cost and it does not appear on any calculator.
- Outbuildings and hard landscaping. Garages, boundary walls, driveways, gates and garden walls are part of the building for most policies and are routinely omitted.
- Conservation and listing constraints. Where a property is listed or sits in a conservation area, the rebuild has to satisfy the consent regime as well as the building regulations.
The three-year cycle, and why annual indexation is not enough on its own
The RICS position is a two-part discipline rather than a single event. A desktop update each year keeps the figure moving with construction inflation. A full reassessment, with a site visit, happens in every third year — and immediately if the building has been extended, converted or materially altered.
Indexation alone fails for a specific reason. An index moves the old figure forward; it cannot correct an old figure that was wrong to begin with, and it knows nothing about the loft conversion you did in 2023. Three years of diligent indexation applied to a bad starting number produces a confidently wrong answer.
Alterations are the trigger people miss most often. A single-storey rear extension can add a fifth to the footprint and nothing on the insurance schedule changes unless somebody tells the insurer.
What underinsurance actually does to a claim
Here is the part that surprises people: underinsurance does not only bite on total losses. It bites on small ones.
Most commercial policies, and many residential ones, contain an average clause. If the sum insured is materially below the true reinstatement cost, the insurer can scale the settlement down in proportion — so a kitchen fire claim on a building insured for two-thirds of its rebuild cost can be settled at two-thirds. The RICS standard notes that insurers have often allowed a margin of error before applying average, with cover sometimes written on an 85 per cent average condition, but that margin is a courtesy of the policy wording, not a right.
The practical consequence is that the household discovers the problem at the worst possible moment, with a loss adjuster on site and no way to fix it retrospectively.
What most guides on this get wrong
Plenty of articles imply that if you had a home survey, your reinstatement figure is sorted. That is not quite true, and the distinction matters.
An RICS Level 2 Home Survey in its survey-and-valuation form includes an insurance reinstatement figure, which is genuinely useful at the point of purchase and enough for a great many standard houses. But it is produced alongside a condition inspection, not as a standalone costing exercise, and it is a snapshot on the day you bought.
A dedicated assessment is a different instruction: measured, itemised, and written to be handed to an insurer. Where a property is listed, of non-standard construction, unusually large, or commercially let, that is the document the policy needs. If you are weighing up which report you need at purchase, our guide to the difference between a Level 2 and a Level 3 survey sets out what each one covers.
Lincolnshire specifics worth knowing
Our patch makes this more than a paperwork exercise. Lincoln’s uphill streets, Stamford, Southwell and the Wolds villages carry a lot of limestone, lime mortar and natural slate, and a like-for-like rebuild in those materials is priced nothing like a cavity-wall replacement.
Rural Lincolnshire adds another layer. Converted barns, former agricultural buildings and properties with long private accesses all push the cost of getting plant and materials to site. So does anything in a flood-risk location, where the rebuild specification may not simply repeat what was there.
Listed stock is the sharpest case. Consent conditions can require traditional materials and methods throughout, and the cost of that is invisible from the street. We cover what that means for buyers in our guide to surveying a listed building.
When to get one done
- You are buying a listed, period or non-standard property, or one with significant outbuildings.
- You have extended, converted a loft or garage, or changed the building materially.
- Your last assessment was three or more years ago, or you have never had one.
- You are a landlord or leaseholder with a service-charge obligation to insure.
- Your insurer or broker has asked for evidence supporting the declared value.
If none of those apply and you own a conventional modern house, an annual sanity check against a reputable rebuild calculator may be all you need. Honesty about that is part of the advice.
Want your rebuild figure checked properly?
We prepare reinstatement cost assessments across Lincoln, Lincolnshire and Nottinghamshire, for houses, listed buildings and commercial premises. Fees are quoted per property once we know the address, the construction and what the insurer has asked for — any guide figure is an indication, never a quote.
See our RICS property valuation services, or get in touch with the team to talk it through.
How often should a reinstatement cost assessment be updated?
RICS advises adjusting the sum insured annually to reflect construction inflation, with a major review and reassessment every three years, or earlier if the building has been significantly altered. An extension, loft conversion or change of use should trigger a reassessment straight away rather than waiting for the cycle.
Is the rebuild cost the same as what I paid for the house?
No. The purchase price includes the land and reflects market demand; the rebuild cost does not, because the plot survives a total loss. Depending on the property and its location the rebuild figure can sit well below the price paid or well above it, which is why one cannot be used as a proxy for the other.
Who can carry out a reinstatement cost assessment?
It is prepared by a surveyor working to the RICS professional standard on reinstatement cost assessment of buildings. The assessment involves a site visit and measurement, and the report sets out what has been included — demolition, site clearance, professional fees — and any exclusions, so the insurer can see how the figure was built.
What happens if my building is underinsured when I claim?
Where a policy contains an average clause, the insurer can reduce the settlement in proportion to the shortfall, and that applies to partial losses as well as total ones. Some policies allow a margin before average is applied, but it depends entirely on the wording, and it cannot be corrected once a loss has occurred.
