How much does a house extension cost in London?


The expense of constructing a side or rear house extension in London is subject to considerable variation, contingent on various factors such as the dimensions and intricacy of the extension, the materials utilized, and the location of the property. Typically, the cost of constructing an extension in London is higher compared to other regions of the UK due to elevated construction expenses and property values.


To give a ballpark figure, building a rear house extension in London can cost between £1,500 to £2,600 per square meter for an elementary design and standard quality materials. However, the cost can rise to £4,000 or more per square meter for a luxurious design and top-quality materials.

Other factors that influence the cost of constructing an extension in London consist of:

  • Planning permission and building regulations charges
  • Structural engineer fees
  • Groundwork and foundation expenses
  • Roofing and cladding fees
  • Windows and doors expenses
  • Plumbing and electrical work costs
  • Finishing and decoration charges

It's worth noting that these are simply approximate estimates, and the actual cost of building an extension in London is dependent on the specific details of your project. It's always recommended to obtain a comprehensive quote from a reputable company with a lengthy track record before commencing any construction.



Return On Investment

The ROI for building a house extension in London relies on many factors like: extension's cost, property type, location. In general, a skillfully designed and constructed house extension can augment the property value in London by up to 20%.


As per a report by the Royal Institution of Chartered Surveyors (RICS), median return on investment for a house extension in London is about 71%. In other words, for every £1 spent on the extension, the property value could increase by £0.71.


However, keep in mind that this is just an average.Actual rate of return for a house extension in London and surrounding areas will depend on the specifics of your project. The ROI can be affected by many factors, such as the extension's size and quality, location, and the current state of the property market.


Potential increase in property value, a house extension can offer other benefits, such as more living space and improved functionality. The decision to construct a house extension must be based on various factors, including budget, lifestyle needs, and long-term goals.

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