Wraparound extension costs

A wraparound extension (a combined side and rear extension) can cost anywhere between £2,000–£3900+ per square metre to build, based on figures reported by residential architects and designers on Design for Me in 2022. 



We asked our community of residential architects and design professionals for their experience of domestic projects and how they estimate new jobs. Prices are generally higher in London and the south east.


Extension pictured above by Richard, architect from Lambeth, London. Click here to see more and shortlist them for your home project.

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Let’s start with an example of a basic, single storey wraparound extension of 30m².


At £2,000 per m², the basic build cost would be roughly £60,000.

In London and some parts of the south east, these figures could be between £2,300-£2,800 per m². See our separate post on house extension costs in London and the south east here.


  • Add on 10-15% for professional fees (architect, planning application, building regs, structural engineer) (£9,000 at 15%)
  • VAT (£12,000)
  • Add at least £10,000 for a kitchen (again, completely depends on your specification, £10,000 should get you a lower-mid range kitchen with appliances).


For a 30m² wraparound kitchen extension you should cost upwards of £91,000. 

When arranging finance, you should always allow a contingency and in todays economic landscape, we would recommend allowing 20%.

Therefore, your minimum budget for a basic 30m² wraparound extension should be £109,200.


Finishes and fittings

Above costs assume modest finishes, fittings, electrics and lighting. Think simple painted walls, carpet or vinyl.

  • If you’re wanting higher-end finishes, e.g. tile finishes, timber flooring fitted joinery etc the costs will increase.
  • Sliding or folding doors are a popular addition to extensions at the moment. Glazing should be used sparingly, however, if you are looking to keep costs down.


Are there any complex site constraints?

Your builder will need to include additional costs in their quotation if any of the following apply.

  • Your soil type and ground conditions may present more costly construction methods / techniques.
  • Limited access to the site. Will it be easy for the builder to bring in tools and machinery easily?
  • Existing structure. Are you removing any structural walls? If so, there will likely be additional costs for steelwork.
  • Are you moving any pipework, drainage, gas meters?


Materials and construction techniques

  • Consider the type/ quality of construction materials involved and the type of construction.


Here are some other articles you may find useful

Cost advice

Two storey extension costs: https://designfor-me.com/project-types/extensions/guide-to-costs-and-planning-permission-for-a-two-storey-extension/

Renovation and extension costs in the SE: https://designfor-me.com/cost-planning/renovation-and-extension-cost-per-square-metre/

Loft conversions: https://designfor-me.com/cost-planning/how-much-does-a-loft-conversion-cost-2022/


Planning – Is a wraparound extension permitted development?



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Emily  Design for Me

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