How Do You Calculate Rebuild Cost for Landlord Insurance?
Measure the gross internal floor area of the property, multiply it by the rebuild rate for its construction type and region, then add demolition, site clearance and professional fees. For a standard house the free calculator the ABI hosts with BCIS will get you there in about ten minutes.
Rebuild cost is what it takes to put the building back, not what a buyer would pay for it. Your landlord buildings insurance premium and every claim settlement are worked out from that single figure.
Get it wrong and the insurer can cut a claim by the same proportion you were short. Research by RebuildCostASSESSMENT.com, drawn from more than 29,000 property assessments, puts 70% of UK properties below the sum they should be insured for.
Rebuild cost is what it takes to put the building back, not what a buyer would pay for it, and both your premium and any claim settlement are worked out from that figure. Take the gross internal floor area, apply the rebuild rate for the construction type and region, then add demolition, site clearance and professional fees. Listed, timber-framed and unusual properties need a professional reinstatement assessment, and index linking only keeps a sum insured accurate if it started out right.
Compare landlord buildings insurance quotes once you have your sum insured.
- What is rebuild cost and why does your insurer ask for it?
- How do you work out the figure step by step?
- What must the sum insured include?
- How should you handle VAT in the rebuild figure?
- What happens if you get the number wrong?
- Which properties need a professional reinstatement assessment?
- Does index linking keep your sum insured accurate?
- How does rebuild cost work for flats and portfolios?
- Frequently asked questions (FAQs)
What is rebuild cost and why does your insurer ask for it?
Rebuild cost is the price of reconstructing your property from bare ground to the standard it is in today. It is the sum insured on the buildings section, and it is the ceiling on anything the insurer will ever pay.
What the sum insured buys you
It covers the structure, roof, fitted kitchen, bathroom suite, boiler and fixed flooring, which is the same scope as buildings insurance on an owner-occupied home. What it never covers is the ground the property stands on.
Land survives a fire, so you only insure the parts that can burn, flood or fall down. Almost every buy-to-let mortgage makes cover at the full rebuild value a condition of the loan.
Why market value points you the wrong way
The ABI is blunt about it in its home insurance guidance: insure the building for its rebuilding cost, not what you paid or what it would sell for now.
On a £400,000 terrace in a strong postcode the rebuild figure often sits nearer £200,000, because roughly half the price is land and location. In remote rural areas the two can almost meet, since land is cheap and access is not.
How do you work out the figure step by step?
Take the floor area, apply a rate per square metre, then add the costs that come before and after the build itself. Three measurements and one lookup will put most standard houses within a few per cent.
Measuring the gross internal floor area
Measure from the inside face of the external walls on every floor, and include hallways, landings and stairwells. Leave out detached garages and outbuildings unless they are built into the main structure.
Finding the rate per square metre
The free rebuild calculator the ABI hosts with BCIS, the Building Cost Information Service, does that lookup from BCIS construction cost data. It costs nothing to use, asks you to register, and is built for conventional houses, bungalows and flats rather than anything unusual.
The ranges below are indicative 2026 rates for standard brick and block construction, and work best as a sanity check on the calculator output.
| Property type | South East | Midlands | North and Scotland |
| Terraced house | £1,850 to £2,100 | £1,550 to £1,750 | £1,400 to £1,650 |
| Semi-detached house | £1,950 to £2,200 | £1,650 to £1,850 | £1,500 to £1,750 |
| Detached house | £2,050 to £2,300 | £1,750 to £1,950 | £1,600 to £1,850 |
| Purpose-built flat | £2,100 to £2,400 | £1,800 to £2,000 | £1,650 to £1,850 |
| Bungalow | £1,900 to £2,150 | £1,600 to £1,800 | £1,450 to £1,700 |
Adding what the calculator leaves out
- Demolition, skips and making the plot safe before a single brick is laid.
- Professional fees at 10% to 15% of the build cost, covering architect, structural engineer and building control.
- Scaffolding and access costs where the property sits on a narrow lane, in a city centre or behind a shared alley.
- Any extension, loft conversion or high specification refit added since the last time the figure was set.
What must the sum insured include?
Everything needed to get from a cleared plot back to a lettable property: demolition, site clearance, the build, professional fees and compliance with today’s Building Regulations. Land value and your tenant’s possessions stay out.
The costs landlords leave out
The gaps are nearly always at the two ends of the job rather than in the brickwork. Tenants’ belongings need their own contents insurance rather than a place on your schedule.
| Cost item | In the sum insured? | What landlords miss |
| Demolition and site clearance | Yes | Skips, hoardings and making the plot safe before rebuilding starts |
| Professional fees | Yes | Architect, structural engineer and building control, usually 10% to 15% |
| Meeting current Building Regulations | Yes | Insulation, fire separation and wiring the property never had to meet |
| VAT | Depends | Standard rated on repairs and on every professional fee |
| Outbuildings, walls, gates and drives | Usually | Only if the schedule lists them, so read the wording |
| Land value and location premium | No | This is the gap between rebuild cost and the sale price |
| Tenant’s own belongings | No | Their contents policy, never your buildings sum insured |
Your rebuild has to meet today’s rules
A house built in 1935 gets rebuilt to 2026 standards, not 1935 ones. Section 36 of the Building Act 1984 lets a council require work that fails current regulations to be taken out and done again.
How should you handle VAT in the rebuild figure?
If you cannot reclaim VAT, your rebuild figure has to include it. The catch is that VAT falls differently on a total rebuild than it does on a repair.
A total rebuild can be zero rated
HMRC treats a dwelling demolished to ground level and constructed again as new build work, which is zero rated under VAT Notice 708. On a genuine total loss the bricks and labour may carry no VAT at all, though few landlord claims destroy the whole structure.
Repairs and fees always carry it
Work to an existing building is standard rated, and VAT Notice 708 states that architectural, surveying, consultancy and supervisory services are always standard rated. Most claims are partial, so most claim spending attracts VAT at 20%.
Let through a VAT registered company that can recover the tax and you should exclude VAT from the sum insured. Individual landlords who are not registered should include it and tell the insurer which basis they used.
What happens if you get the number wrong?
Underinsure and the average clause reduces your payout by the same proportion you were short, even on a small repair. Overinsure and you pay premium every year for cover you can never claim.
How the average clause cuts a partial claim
Partial claims are the norm, and they are where the clause bites. The ABI reported the average domestic subsidence claim hitting a record £20,000 in the second quarter of 2026, with £72m paid out over those three months.
RebuildCostASSESSMENT.com found that underinsured buildings carry cover for an average of just 67% of what they should. Here is what that does to a £60,000 fire claim on a Leeds semi.
| Line | Figure |
| Correct rebuild cost | £220,000 |
| Sum insured on the policy | £150,000 |
| Proportion actually insured | 68% |
| Cost of the fire damage | £60,000 |
| Settlement after the average clause | £40,909 |
| Policy excess deducted | £500 |
| What lands in your account | £40,409 |
| Your shortfall | £19,591 |
The excess comes off the reduced settlement, not the full loss. Nearly £20,000 of a claim you believed was fully insured stays with you.
Where you can push back
If the shortfall traces back to careless answers at quote stage rather than a policy condition, the Consumer Insurance (Disclosure and Representations) Act 2012 sets out proportionate remedies instead of a flat refusal.
A deduction you think is unfair can go to the Financial Ombudsman Service once the insurer issues its final response, so keep the calculation you used and the date you ran it.
Which properties need a professional reinstatement assessment?
Listed buildings, non-standard construction and anything heavily extended need a surveyor rather than a calculator. A RICS reinstatement cost assessment typically runs £300 to £1,500 depending on size and complexity.
Listed buildings and conservation areas
Grade I, II* and II properties go back with matching materials and heritage trades, commonly 30% to 60% above the rate for a modern equivalent. Listed building consent adds time and fees on top.
Non-standard construction
Thatch, cob, stone, timber frame, steel frame and precast concrete systems all sit outside a calculator’s range. These properties need non-standard property cover and a surveyor’s figure before most underwriters will quote at all.
The rics standard behind the report
RICS reissued its professional standard on reinstatement cost assessment of buildings as a third edition in June 2024, and it sets how the surveyor gathers information and calculates the figure. Ask for a report written to that standard rather than a one-line valuation.
Does index linking keep your sum insured accurate?
Index linking lifts your sum insured each year in line with building cost inflation, and it is worth leaving switched on. What it cannot do is repair a starting figure that was wrong.
How insurers apply the index at renewal
Most landlord policies adjust the buildings sum insured automatically using a house rebuilding cost index published by BCIS. The change shows on the renewal schedule as a revised sum insured, usually without a separate premium line.
Why indexation multiplies an old mistake
The index applies a percentage to whatever number is already sitting there. Insure a £220,000 rebuild for £150,000 and five years of indexation leaves you exactly as short in proportion, so the average clause still cuts a claim and your loss of rent cover can be reduced with it.
Recalculate from scratch every three years and let the index cover the years between. That habit removes most of the underinsurance risk on a standard let.
How does rebuild cost work for flats and portfolios?
For a leasehold flat the freeholder insures the structure and you insure everything else. For a portfolio, every address needs its own rebuild figure even when they share one schedule.
Leasehold flats and the block policy
The freeholder buys a block of flats policy for the whole building and recharges it through the service charge. Ask the managing agent for the schedule so you can see the figure for the block and the excess you would face.
Declared value, sum insured and day one uplift
Larger block and commercial policies separate the two figures. The declared value is the reinstatement cost at the start of the period, and the sum insured adds a day one uplift on top, commonly 15% to 25%.
That uplift absorbs build cost inflation across a rebuild that can run two years on a block. Where no declared value is shown, average is measured against the whole figure instead.
Portfolios and specialist lets
A multi-property policy or a portfolio policy still needs a separate rebuild figure per address, because average is applied property by property.
HMO insurance and holiday let cover follow the same method, though conversion work often lifts an HMO above a family house of the same floor area.
A shop with a flat above sits under commercial property insurance and needs a commercial reinstatement assessment covering both uses.
Frequently Asked Questions (FAQs)
Yes. Insurers and surveyors use the terms interchangeably for the cost of putting the building back, and both exclude land.
It is the buildings sum insured on your policy schedule. Your mortgage valuation, survey report and deeds may also carry a figure, though older ones date quickly.
Use it as a starting point, then check it against a current calculator. A valuation from three or four years ago will usually sit below today’s build costs.
Only where the schedule lists them. Boundary walls, gates, paths and drives are often covered but landscaping and planting rarely are.
Yes. The ABI and BCIS calculator is free after registration and suits standard houses and flats, and it pairs with the buildings section of a landlord policy without any extra assessment.
That is normal in low value areas and for listed or remote properties. Insure the rebuild figure anyway, because that is what an insurer has to spend to reinstate.
Yes, and before the work starts where you can. An extension changes the floor area, the rebuild cost and the risk during the build.
No, but the cover does. Most policies restrict perils after 30 to 45 days unoccupied even though the sum insured stays the same.
Expect £300 to £1,500, driven by floor area, construction type and listed status. On a listed or heavily extended property it is cheaper than one averaged claim.
It can. Loss of rent limits are often set as a percentage of the buildings sum insured, so a low rebuild figure shrinks the rent cover with it.