Wraparound Extension Cost Calculator

A wraparound is a rear and a side return built as one. It is the biggest change you can make to a ground floor, and it is priced accordingly.

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Priced by floor area
Steels and openings priced
Party wall included
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Price a wraparound in 30 seconds

4 steps. Covers floor area, spec, structural opening and region.

How this calculator works

A wraparound is priced on total new floor area, but the structural work is what separates it from two smaller extensions built separately. Wrapping the corner means the existing rear wall largely disappears, which needs multiple steels and often a corner post — that is the single biggest line after the shell itself.

The figures exclude the kitchen, which is where a wraparound usually ends up. Budget separately: a fitted kitchen in a space this size typically runs £8,000–£30,000 depending on specification.

Wraparound costs by size (2026)

SizeTypical 2026 costNotes
Small (~15 mยฒ)ยฃ55,000โ€“ยฃ75,000Modest rear plus narrow return
Mid (20โ€“25 mยฒ)ยฃ72,000โ€“ยฃ105,000The common wraparound
Large (30โ€“40 mยฒ)ยฃ90,000โ€“ยฃ130,000Substantial open-plan ground floor
Extra-large (40 mยฒ+)ยฃ110,000โ€“ยฃ140,000+Whole rear elevation reworked
Londonยฃ95,000โ€“ยฃ125,000Typical mid-size, London rates
South Eastยฃ82,000โ€“ยฃ110,000

Ranges match our wraparound cost guide. Kitchen fit-out is excluded throughout.

Wraparound calculator FAQs

Yes, meaningfully. One set of foundations, one roof structure, one mobilisation and one party wall process rather than two. Building the rear now and the side in three years typically costs 20โ€“30% more in total, and you live through the disruption twice.

Usually yes. Permitted development covers rear and side extensions separately with their own limits; wrapping the corner generally exceeds them. Budget eight weeks for a householder decision and start the drawings early.

Because you are removing the corner of the house. That needs beams in two directions and usually a post where they meet, plus a structural engineer to size them and often padstones or new foundations beneath. It is the part of the job that must not be value-engineered.

No. A wraparound usually becomes a kitchen-diner, but fit-out varies too widely to fold in โ€” ยฃ8,000 to ยฃ30,000+ depending on units, worktops and appliances. Budget it as a separate line.

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