How much Does an Extension Cost?

The cost of an extension depends upon a number of factors, thes include the following:

• Foundation type, these may need to be simple strip foundations, raft foundations or mini piles, it all depends on the soil conditions.
• What the extension will be used for;  For instance a kitchen extension will cost more than a bedroom extension as it has more fixtures and fittings inside.  
• Whether the extension is to be single storey or two storey.
• How much glazing you require.

Depending on your location within the UK a typical extension will cost the following per m2.

• Basic quality: £1,000 £/m2 to £1,680 £/m2
• Good quality: £1,680 £/m2 to £1,920 £/m2
• Excellent quality: £1,920 £/m2 to £2,160 £/m2

Remember that the standard of specification you choose will have an enormous influence on the build cost.

A two storey extension will not cost much more per square metre than a single storey because, aside from the extra interior fixtures and finishes, you are only adding walls and floor joists — a roof and foundations are required whether your extension is single or two storey.