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Garage Extension Cost & Prices 2023

A garage extension can be a great addition to your house to maximise all the space you have available.

Because the garage is usually separate from the rest of the living areas, disruption can also be kept to a minimum and you can carry on living as you were.

In this article, we’ll cover the costs of a garage extension, factors that affect the cost and other common questions related to garage extensions.

Average Cost Per m²

We worked with a quantity surveyor to price up a typical garage extension. Rates below are for the south-east of England for a garage extension with brick external walls.

External Walls£300/m²
Windows & External Doors£180/m²
Floor Finishes£18/m²
Furniture, Fixtures, and Equipment £82/m²
External Works (Drainage)£50/m²
Prelims of Above Works @ 15%£145/m²

Factors that Affect the Cost

Because extending a garage is a complex job, there are various factors that can affect the prices above. These include the following items below.

Size of Garage

The rates given above based on a 10m² garage.

For much larger garage size you should expect the cost per m² to reduce slightly. Likewise the smaller it gets should get slightly more expensive per m².

Generally speaking, you can expect a £50/m² swing from 5m² to 10m² and likewise to 15m².

There expect to pay £50/m² more going from a 10m² to 5m² and save £50/m² going from 10m² to 15m².

Garage Door Specification

A starting price would be around £775 inc VAT for a standard up and over. Roller doors will start from around £850 Automated doors will start from around £1250 but a high-end electric garage door can go to £3,000+.

The door type, size and colour can all affect the cost.

Insulated vs Uninsulated

Because most garages are just storage, there are fewer insulation requirements. If you are planning to make it liveable for example, then expect to pay an extra 10% on all items for a total of £1,100.

Wall & Ceiling Finishes

Most garages will usually use a fair-faced block finish for the wall. However, if you do use plasterboard and paint, add an extra £40/m². Exposed rafters are also standard for the ceiling, but again if plasterboard and paint are required, this could add a similar amount.


Areas in the south of England and London will be higher than in other parts of the country. The prices quoted in the table above apply for the South East or Outer London area. The adjustments below can be used to calculate costs in your area.

Region% Adjustment
South East (Southampton, Oxford, Kent, Outer London)0
Inner London+4%
South West (Bristol, Exeter)-4%
West Midlands (Birmingham)-10%
East Midlands (Northampton, Nottingham, Leicester)-10%
East Anglia (Cambridge, Norwich, Ipswich)-5%
North West (Liverpool, Manchester)-12%
Yorkshire and Humberside (Leeds, Sheffield)-11%
North East (Newcastle, Sunderland)-10%
Scotland (Edinburgh, Glasgow)-6%
Wales (Cardiff, Swansea)-9%
Northern Ireland (Belfast)-12%

Get Pricing on Garage Extensions Near You

We’ve done our best to give you a good idea of what you can expect to pay for a garage extension.

However, our guides are not a substitute for a fixed quote specifically for you.

We work with all the best garage extension specialists ready to price your job. Get free, no-obligation quotes in your local area and compare prices using the form below.

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About the Author

Alex Johnson is a qualified quantity surveyor and writer with a passion for conducting original research and uncovering the true cost of jobs. His cost data has been referenced by EDF Energy and the Scottish Government.