The average cost of building an extension in Essex is £27,000 for a single-storey rear extension measuring 20 square metres in ground floor area. A 20 square metre two-storey rear extension would usually cost in the region of £43,000.

Although the above is an average, extensions do vary significantly in their dimensions and specification and there are a couple of variables which will determine your total house extension cost.

Size of area

Generally, the larger your extension, the less it will cost per square metre due to economies of scale coming into force on greater building projects. On average, a small single-storey rear extension measuring 12 square metres in ground floor area can cost as much as £1,700 per square metre. Whereas a large 60 square metre single-storey rear extension can cost in the region of £1,200 per square metre.

Number of storeys

In the same manner as economies of scale come into effect on extensions with a larger floor area, two-storey extensions (or more) do not cost double of equivalent single-storey extensions. As a general rule, a two-storey extension will cost 60% more than an equivalent single-storey extension. For example, where a single-storey rear extension measuring 25 square metres would cost in the region of £33,000, a two-storey rear extension with an equivalent ground floor area would cost in the region of £53,000.


Bi-Fold Doors

It is increasingly popular to install 3 metre and bigger sliding-folding doors as patr of the extension to bring the outside, in and the inside, out. As beautiful as these doors are, their installation costs do start from around £4,000 so are not recommended if you are on a very tight budget.

Roof lanterns

It is increasingly popular to install roof lanterns into a flat roof. They flood the room with light and look fantastic. Installation coats start from £1,500 and upwards.

Velux windows

A great choice for any pitched or lean-to roof. The best roof window money can buy. Discreet, contemporary and low maintenance with remote control operation for hard to reach places and rain sensor. Installation coats start from £450.00 and upwards.

Function and fixtures

How you use your new extension will also play a role in your total house extension cost. For example, a kitchen installation will require a greater element of plumbing, waste and electrical services to be extended from your existing home than what would be required if your new extension was to function as a dining room. In this scenario, you would also need to account for the cost of a kitchen installation.

The cost of all your furniture and fixtures is entirely ruled by your budget. You can easily spend £70,000 on new designer furniture and fixtures, especially if you are wanting a bespoke kitchen, or you can spend £2,000 for cheaper high-street equivalents. Hence, it is hard to provide an average cost for these elements of an extension.

The average extension will take four weeks to complete but is dependent upon your ground conditions, access and the fixtures which are required (e.g. kitchens).

All side, rear, single and multiple storey extensions will require building regulations approval from your local authority.

If you have any further questions regarding your extension in Essex or would like a fixed price for us to create your new space, please feel free to contact us and arrange a free home visit.

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