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How much does it cost to build a wraparound extension?

5 min read
Oct '25 • by Heather

Quick summary

Building a wraparound extension costs between £75,000 and £145,000 in London or £60,000 to £120,000 outside, for around 45 sqm, excluding VAT and fit-out costs. Factors like location, materials, and design complexity can raise the price. Keep in mind, additional expenses include architects, structural engineers, and fittings.

A wraparound extension, unlike a standard rear addition, utilises space to the back and side of your property. Essentially, they combine both a side and rear extension, merging them into one continuous space. They’re a great project for period properties, which typically have a lot of dead alleyway space. However, plenty of homeowners find this extension desirable as it can add a lot of space without eating up too much of your garden.

So, how much do they cost? Because of the extra structural work involved, wraparound extensions tend to be most costly than their rear and side counterparts. To discover how much you’ll need to budget, here are some rough costs to bear in mind…

How much to build a wraparound extension?

We estimate that building a 45 sqm wraparound extension could cost...

  • £75,000 to £145,000 in London
  • £60,000 to £120,00 outside of London

Try our construction cost calculator tool and get a tailored construction estimate in minutes.

Please note: the above estimates do not include VAT at 20%. They also do not include key fit-out items and assume the existing property, soil, drainage and foundations are in a good/adequate condition. It is also assumed that existing rooms affected by the extension require decoration only.

How much will construction cost?