What is a wrap-around extension?
A wrap-around combines a side return infill with a rear extension, so the new space wraps around the back addition in an L shape. It is the largest single-storey extension possible on a Victorian terrace, typically adding 25 to 35m² and costing £85,000 to £140,000.
A wrap-around does both jobs at once: it fills the side return and extends beyond the original rear wall into the garden. The result is a large rectangular ground floor across the full width and depth of the plot, usually configured as a single kitchen, dining and living space with the original back addition absorbed into it.
It is more efficient per square metre than doing the two extensions separately, because the foundations, roof and glazing are all one continuous package. If you are considering a side return now and a rear extension later, doing both together will cost meaningfully less than the sum of two projects, and avoids building a wall you later demolish.
The constraints are planning and garden. Going beyond 3m from the original rear wall on a terrace takes you outside standard permitted development into the prior approval route or a full application, and a wrap-around will often exceed the 50 percent curtilage rule on a Fulham terrace with a small garden. Both are checkable before design, and both are worth checking first.
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