How to calculate the rebuild cost of your home

When you get buildings insurance quotes you will be asked about the rebuild cost of your home – here’s why and how to give an accurate figure.

In a worst case scenario, for example if your home was completely destroyed by a catastrophic event such as fire or explosion, your insurance company would be responsible for rebuilding your home and paying for it.

So it stands to reason that your insurer needs to know how much this will cost. As the policyholder, it will be your responsibility to obtain the correct rebuilding cost for your home.

It’s important to give an accurate figure for house rebuilding costs so you are not over or under-insured.

What does rebuild cost mean?

The rebuild cost is the amount it would cost to completely rebuild your home from scratch if it was destroyed beyond repair. The cost will vary according to the size, age and type of property you have.

It includes the price of:

  • demolition 

  • debris clearing 

  • architects 

  • planning costs 

  • labour

  • materials

The rebuild cost doesn’t take into account:

  • the value of the land

  • factors that affect house prices such as transport links and school catchment areas

The rebuild cost will be different from the market value or the sale price of your home. 

Why does the rebuild cost matter?

You need to know your home’s rebuilding costs for insurance purposes.

When you buy buildings insurance, or a combined buildings and contents insurance policy, the insurer will ask how much it will cost to rebuild your home. 

This is because a buildings insurance policy, or combined policy, covers you for structural damage to your home, and the cost of rebuilding it if it is completely destroyed.

It is worth investing some time, and possibly money, into ensuring the figure you give your insurer is correct. 

The risks of under-insuring

Under-insuring your home, whether deliberately to reduce your insurance premium or unintentionally, can have significant consequences. 

It could mean that your insurer will reduce the claims payout by the percentage that your property is underinsured by.

For example, if you told your insurer the cost of rebuilding your home was £150,000 but in actual fact it was £200,000, you would be underinsured by 25%. So if your house was destroyed and you had to make a claim, it could be reduced by 25%.

The risks of over-insuring

In the same way, if you overestimate your home’s rebuild cost you could end up paying more for your home or buildings insurance than necessary.

How do you calculate your home’s rebuild cost?

How you should find out your home’s rebuild cost depends on whether you own:

  • a standard brick-built house

  • a home constructed from non-standard materials

  • a listed building

  • a flat

How to calculate the rebuild cost of a house

If you live in a house constructed from standard materials, such as bricks, there are two ways to calculate its rebuild cost:

If you have recently bought your home, the rebuild cost will be on your mortgage valuation or deeds.

How to use the Building Cost Information Service (BCIS)

You can use the RICS’s Building Cost Information Service (BCIS) to calculate the cost of rebuilding your house for insurance purposes.

To use the calculator you need to register with an email address and accept the terms and conditions of use. 

Once registered, you will be able to use the calculator 4 times in any 12-month period. 

You’ll need to input the following information:

  • whether the property is a house, bungalow, or flat

  • its style (i.e. detached, terrace etc)

  • the number of storeys

  • the postcode of the property

  • the year it was built

  • the external floor area (in metres squared or feet squared)

  • the number of bedrooms and bathrooms the property has

  • whether it has garage space or a cellar

  • the wall type and roof type

  • whether it’s a listed or unusual property

The calculator will then give you a rebuild figure for rebuilding your home to its existing design in modern materials, using modern techniques.

The figure given will cover rebuilding the structure of the property including the foundations, walls, roof, floors, doors and windows, built-in fittings (i.e. kitchen and bathroom), plus installation for heating, hot and cold water, gas, electricity, lighting and ventilation.

However, it won’t include things like loose fittings and furnishing such as carpets and cookers.

How to calculate the floor area

It’s easiest to measure your home’s area from the outside. 

Measure the length and width of the ground floor walls, then multiply these two figures together.

If the upstairs is an identical size to the downstairs, simply double the ground floor area. If it’s different, or you have more storeys, calculate each floor separately and add it to the ground floor result. 

How to calculate the rebuild cost of a home constructed from non-standard materials

Most homes are built with brick or stone walls with a roof made of slate or tile.

A non-standard construction is basically anything that falls outside of this definition. The construction might include:

  • glass, plastic or fibreglass

  • concrete, metal, wood or flint stone walls

  • asphalt or shingle

  • steel or timber frames

  • corrugated iron walls or frames

  • thatched properties

  • flat roofs 

  • prefabricated concrete houses 

  • wattle and daub

If your home is made of non-standard materials, its rebuild cost may be higher than its market value. 

If you live in a home made of non-standard materials, you should contact a chartered surveyor and get a survey done to calculate rebuilding costs.

How to calculate the rebuild cost of a listed building

To find out if you live in a listed building you should visit the relevant website for your country and conduct a search.




Northern Ireland:

If you live in a listed building or one with special architectural features, you should contact a chartered surveyor to get a survey done to calculate rebuilding costs.

How to find a chartered surveyor

You will need to hire a chartered surveyor if:

  • your house is built from non-standard materials

  • you live in a listed building

  • you want more details than provided on a basic BCIS calculation

You should visit the RICS website to find a chartered surveyor. You can search for a surveyor near you by entering your town or postcode.

The surveyor will carry out detailed measurements of your home and then prepare a professional Rebuilding Cost Assessment. This will cost about £250.

How to calculate the rebuild cost of a flat

Most flats are leasehold. If you own a leasehold flat in a block of flats, the buildings insurance will normally be the responsibility of the freeholder or their managing agent.

However, leaseholders pay for buildings insurance via service charges. 

If you own a share of the freehold of your block, you and the other leaseholder are jointly responsible for the buildings insurance. In this situation you’d normally take out one buildings insurance policy for the entire block, and share the cost.

It’s best to speak to a surveyor or insurance broker for advice about this.

Do I need to update my home’s rebuild cost?

With most insurers, you won’t be required to update the rebuild of your property at renewal. 

Some insurers will ‘index link’ their buildings insurance policies, meaning they will automatically increase the rebuild cost of your property in line with inflation.  This should prevent you from being under-insured

If you make any improvements or renovations to your home – e.g. an extension, a loft conversion or a new kitchen – you should re-calculate your home’s rebuild cost to make sure you are fully covered.

6 November 2020