Brick house

House Extension Cost Calculator
Extensions invlove a number of elements from various trades, starting from digging and laying concrete foundations, constructing walls, 
first fix plumbing and electrics, then finally decoration- then extra features can be added like new kitchens, new bathrooms, bifolding doors, roof lanterns. There is a large variety of factors which can affect the cost of a house extension whether its accessebility or high specification fixtures and furnishings. With our house extension price guide we hope to provide you with a fair ballpark figure to start planning the finances of your project.

Below we have broken down different factors of an extension and the different kind of costs involved, but the main factor driving the costs of the build is the size of the extension required. In our experience the basic price for a house extension is £1,800 per m2, so for a 18m2 extension (6m/3m) the cost would be £32,400. This price doesnt include VAT, charged at the standard 20%. This price includes the essntial elements of the build, laying foundations, constructing walls, insulating the structure,installing plasterboard, constructing a sub floor, and basic provisions for plumbing and electrics . This doesn't include decoration , kitchens, bathrooms, structural alterations,  

Extension 15m2 (3m/5m) £22,500

Extension 24m2 (6m/4m) £36,000

Extension 48m2 (6m/8m) £72,000

Extension 15m2 (3m/5m) £27,000

Extension 24m2 (6m/4m) £43,200

Extension 48m2 (6m/8m) £86,400

Adding Additional Floors

There are many sources online which state that adding a first floor will cost 50% of the single stort cost, unfortunately this is not true, again as a rule of thumb your calculation would driven around the size of the project and the specification. So a double story extension with both floors measuring 18m2 would cost £54,000. The main factors driving the cost up is the additional scaffolding required, adaptions to the roof, working at height.

Kitchen & Bathroom Costs 

The price of a kitchen or bathroom will widely vary depending on your requirements and the quality of the products you choose to buy, the typical cost to install a kitchen would range from £8,000 - £25,000 and a bathroom would range from £8,000 - £15,000. We offer a free no obligation kitchen design service which comes with a 3d plan.  

We hope this guide provides you with a guide to help you start planning and arranging finances for your project. 

Please get in touch for more information.