1. What an insurance valuation actually is
An insurance valuation — properly a Building Reinstatement Cost Assessment (BRCA), and once known as a fire insurance valuation — works out how much it would cost to completely rebuild your property if it were destroyed. That figure sets the level of buildings insurance you should carry.
It is not a market valuation, and that's the single most important thing to understand about it. A market valuation tells you what someone would pay for the property. A reinstatement assessment tells you what it would cost to put the building back. The two answer completely different questions, use different methods, and routinely produce very different numbers.
2. Reinstatement cost vs market value
These figures diverge because they're built from different things.
Market value reflects location, income, tenure, planning potential and demand. Crucially, it includes the land — which you can't lose in a fire.
Reinstatement cost reflects only the cost of physically rebuilding: labour, materials, professional fees, demolition and the rest. Land is excluded.
The gap runs both ways. A well-located building might be worth far more than it costs to rebuild — an office worth £4 million but costing £2 million to reinstate, because most of the value is in the land and the location. But it can also run the other way: a modest building in a cheap-to-sell location, built in an expensive or specialised form — heritage fabric, a difficult or constrained site, unusual structure — can cost more to rebuild than it would ever sell for. Insuring for the market value in that second case leaves you badly exposed. Using market value as your sum insured is one of the most common — and most expensive — mistakes we see.
3. Why the figure matters: underinsurance and "average"
If your declared figure is too low, you're underinsured — and most commercial policies contain a condition of average that penalises it.
Under average, the insurer reduces your payout in proportion to the shortfall. A worked example:
- True reinstatement cost: £2,000,000
- You've insured for: £1,000,000 — a 50% shortfall
- You suffer £500,000 of fire damage
- The insurer applies average and pays £250,000
You didn't have a total loss, yet you're £250,000 out of pocket. That's the sting people miss: average bites on partial claims too, not just when the building burns to the ground. Since most claims are partial — a fire in one unit, a flood, an escape of water — underinsurance can quietly undermine every claim you ever make, not just the catastrophic one.
Some policies soften this with a "waiver of average" or a declared-value clause that doesn't penalise you provided you're within a stated percentage (often 85%) of the true figure. That's helpful, but it's not a licence to guess — if you fall outside the tolerance, average returns in full. Over-declaring isn't the answer either: insurers never pay more than the actual rebuild cost, so an inflated figure just means an inflated premium for cover you can never claim. The goal is accurate, not high.
4. What the reinstatement figure includes
A proper assessment is far more than "what would this cost to build." It captures the full cost of reinstatement:
- Demolition and site clearance of what's left standing
- Debris removal and disposal
- Rebuilding to an equivalent specification — and to current building regulations, which can cost considerably more than the original (fire, thermal, accessibility and structural standards have all moved on)
- Professional fees — architects, engineers, surveyors, project managers, typically a meaningful percentage of the build cost
- Statutory fees — planning applications, building control, and any party wall matters with neighbours
- VAT, where applicable — the rules vary by property type and use, and getting the VAT treatment wrong can distort the figure significantly
Listed and heritage buildings deserve special mention: like-for-like reinstatement may require traditional materials and craftsmanship at a multiple of modern build costs, and conservation constraints can rule out cheaper substitutes. A standard cost-per-square-metre approach badly understates these buildings.
5. The terms that trip people up
Sum insured / declared value — the figure on your policy schedule. This is what average is tested against.
Day-one reinstatement — many policies add a percentage "day-one uplift" on top of the declared value to absorb cost inflation during the policy year and the rebuild period. It's a buffer, not a substitute for an accurate base figure — if the declared value is wrong, the uplift is simply applied to the wrong number.
If you don't know which basis your policy uses, that alone is worth checking today.
6. The index-linking trap
Most insurers automatically uplift your sum insured each year using a construction cost index. That sounds reassuring, but it has three blind spots:
- It can't fix a wrong starting figure. Index-linking a number that was never right just keeps it wrong — with compound interest.
- It ignores changes to the building. Extensions, refurbishments and fit-out don't show up in an index.
- It can lag real-world tender inflation. The building-cost spikes of recent years outran some indices, leaving index-linked figures trailing the actual cost of building.
This is why a figure that's been quietly index-linked for a decade is one of the most common causes of underinsurance we find.
7. How the figure is calculated
There are two broad routes to a reinstatement figure, and they are not equal.
A desktop estimate applies a cost-per-square-metre rate to the floor area. It's quick and cheap, and it's how many sums insured were first set — but it's blunt, it misses the features that drive cost, and it's where a lot of underinsurance originates.
A professional assessment starts from the building itself. The surveyor measures it, confirms the construction type and specification, and prices the reinstatement using current building-cost data with the right regional adjustment, then adds the demolition, fees, statutory costs and VAT above. The result reflects your building rather than an average one — which is the whole point.
8. Signs you might be underinsured
You may be carrying the wrong figure if:
- You've never had a professional reinstatement assessment — the sum insured was an estimate, or the market value
- Your figure has been index-linked for years without a fresh assessment
- You've altered, extended or refurbished the building since it was last assessed
- The building is listed or of heritage construction, where like-for-like rebuild is expensive and specialised
- Your figure predates the post-2020 construction cost inflation
9. When to get (or refresh) an assessment
- On acquisition — set the cover correctly from day one, before you inherit someone else's guess
- At least every three years — the interval RICS recommends, with index-linking in between
- After significant alterations — anything that changes the building changes its rebuild cost
- When your insurer or lender asks — funders and insurers increasingly want a professional assessment rather than a declared estimate
10. Whose job is it — landlord or tenant?
It depends on the lease. Under a typical FRI (full repairing and insuring) arrangement, the landlord insures the building and recovers the premium from the tenant through the insurance rent or service charge. But the declared value the landlord sets affects the tenant's exposure too — if the building is underinsured and a claim falls short, the reinstatement gap can land on either party depending on the lease terms. Some leases put the insuring obligation on the tenant directly.
Whichever side you're on, it's worth knowing the figure your policy is built on — not assuming someone else has checked it.
11. Common misconceptions
"My insurer set the figure, so it must be right." Insurers apply the declared value you give them, often index-linked from an original estimate. The accuracy is your responsibility, not theirs.
"It's covered by the market valuation I already have." A market or mortgage valuation measures worth, not rebuild cost, and usually says so in its own caveats. It's not a reinstatement assessment.
"I insured for the full value, so I'm safe." If "full value" meant market value, you may be significantly over- or under-insured — because rebuild cost is a different number entirely.
12. What to do next
Dig out your policy schedule and find the sum insured (and whether it's on a day-one basis). Ask when the figure was last professionally assessed, as opposed to index-linked. If the answer is "never," or "we're not sure," that's the prompt to get a current Building Reinstatement Cost Assessment — a small cost against the size of the gap it can reveal.
Key Takeaways
- Insurance valuation ≠ market value — it's the cost to rebuild, land excluded
- Underinsurance triggers "average" — payouts are cut proportionally, on partial claims too
- The figure is more than build cost — demolition, fees, statutory costs and VAT all count
- Index-linking isn't a safety net — it can't fix a wrong figure or capture alterations
- Reassess every ~3 years, on acquisition, and after any changes to the building
- Know your number — whether you're the landlord or the tenant
FAQs
What's the difference between reinstatement cost and market value?
Market value is what the property would sell for — it includes the land, location and income potential. Reinstatement cost is what it would cost to rebuild the structure after a total loss, with land excluded. Your buildings insurance should be based on reinstatement cost, not market value; the two are often very different figures.
What is the "average" clause?
It's a condition in most commercial policies that reduces your payout in proportion to any underinsurance. If you're insured for half the true rebuild cost, the insurer can pay half of any claim — including partial claims, not just total losses. It's the mechanism that makes underinsurance so costly.
How often should I get a reinstatement cost assessment?
RICS recommends a professional reassessment at least every three years, with index-linking in between, and sooner if you've altered or extended the building or if construction costs have moved sharply. A figure that's simply been index-linked for years is a common source of underinsurance.
Does the reinstatement figure include VAT and professional fees?
Yes. A proper assessment includes demolition and debris removal, rebuilding to current building regulations, professional and statutory fees, and VAT where it applies. Leaving these out is a frequent reason declared values fall short of the true cost.
Is index-linking enough to keep my sum insured accurate?
No. Index-linking can't correct a starting figure that was wrong, it doesn't capture alterations to the building, and it can lag real construction inflation. It's a useful top-up between assessments — not a replacement for one.
Who is responsible for the insurance valuation — landlord or tenant?
It depends on the lease. Under a typical FRI lease the landlord insures and recovers the cost from the tenant, but the declared value affects both parties' exposure. Some leases place the obligation on the tenant. Either way, it's worth knowing the figure your cover is based on.
Need Help?
If you're not sure your buildings insurance reflects the true cost of rebuilding, we can check. Our chartered surveyors provide RICS-compliant reinstatement cost assessments that set your cover at the right level — no more, no less.
Related Services:
- Building Reinstatement Cost Assessments — Set your buildings insurance at the correct level
- Pre-Acquisition Surveys — Know the building's condition and rebuild profile before you buy
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