How to calculate your building sum insured

Establishing the accurate re-building sum insured of your home can be a difficult task. At Macbeth, our private client team provide assistance in this area and can recommend expert professional services from local Chartered Surveyors. In addition, if you would like an approximate idea of the costs, please read our useful guide below.

Firstly, you need to find the external floor area of your home – both upstairs and downstairs. The best way is to go outside and measure the length and width of your home and multiply these figures together. If you cannot measure outside, measure inside and add the thickness of the walls. You can measure either in feet or metres. An integral garage would be included in this calculation. Another tip is to look at the plans from when the property was purchased, this may well provide these measurements.

You now know the ground floor area. For upstairs, you may be able simply to double the ground floor area. If the other floor area is a different size then calculate the upstairs area separately and add the figures together. For three storey houses, only 70% of the floor area of the third storey need be included. A third storey of a house does not mean the attic in a two storey house, unless the roof space has been converted into a third storey.

If you have a separate garage or a garage built on the side of the house, an appropriate amount will need to be added to the rebuilding cost of the house. You will also need to allow an appropriate figure for fences, gates, walls, solar panels, patios, paths, drives, swimming pools, etc.

It is important to take into consideration the quality of the fixtures and fitting and adjust more particularly for expensive bespoke kitchens and bath rooms.  Properties that are listed need special attention and our recommendation would be to seek advice from a building surveyor.

The link to the Association of British Insurance rebuild calculator is – this calculator is provided by BCIS, The Building Cost Information Service of the Royal Institution of Chartered Surveyors.

If you would like help from a professional, please contact Carl Sharp by calling 0118 9165487 or complete an enquiry form and we will recommend a local Chartered Surveyor to you.

* Information correct as of 1st May 2016

Author: Carl Sharp | March 29th, 2011

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Carl Sharp
Get in touch:   Reading: 0118 916 5480   London: 020 7036 8767