Wraparound Extension Drawings in London | Fixed Fee

What makes a wraparound extension different from a rear or side return alone?

A rear extension adds depth at the back of the house; a side return adds width down the alley; a wraparound does both at once, so the new floor area turns the corner of the original building rather than sitting against just one wall. The result is typically the largest open-plan space a single-storey extension can deliver, but it also means more of the original external wall is removed and more of the roof is new, which raises the structural and drainage stakes compared with either extension on its own. Homeowners who start out planning a rear extension or a side return alone often move to a wraparound once they see how little extra it costs to combine the two, since much of the groundwork, roof structure and glazing is shared between them rather than duplicated.

Do wraparound extensions need full planning permission in London?

Almost always, yes. Permitted development allowances are calculated on combined additions to the original house, and a wraparound's depth plus width together generally exceed the volume and footprint limits that apply to a rear extension or side extension considered separately. A Lawful Development Certificate route is rarely viable for a genuine wraparound.

Conservation area status and Article 4 directions, common across the terraced streets where wraparound extensions are most popular, remove permitted development rights further still, so we design every wraparound on the assumption it will go through full householder planning.

Structural design for a wraparound extension

Because the new space turns a corner, the structural frame has to work as one continuous system rather than two independent extensions bolted together.

• A continuous steel or ring-beam frame carrying the roof around the internal corner where the rear and side elements meet
• A glazed roof lantern or rooflight strip often placed at the corner junction, where natural light reaches deepest into the combined plan
• Foundations for both the rear and side elements designed together, so they tie into the existing house consistently
• Bi-fold or sliding doors across the rear elevation, coordinated with the side glazing so the two elements read as one space

Drainage, soil stacks and services in a wraparound extension

Removing most of the original rear and side external walls frequently means the existing soil stack, waste pipes and rainwater drainage that ran down those walls have to be diverted before building work starts. Our drawings show the proposed drainage route, including any new manholes or rodding points, alongside the structural and building regulations detail, so your builder and drainage contractor are working from the same information as the rest of the site team.

Gas, electricity and water supplies that previously ran along the side alley or rear wall often need re-routing too, and boiler flues or extractor terminals that discharged into the alley have to be relocated once it is enclosed. Because a wraparound touches every service run around the back of the house, we map these against the structural layout early, rather than leaving them for the builder to resolve on site.

How much do wraparound extension drawings cost in London?

Wraparound extension drawings start from £2,200, reflecting the full planning application, structural design for the combined frame and, on most projects, building regulations detail bundled together. See the comparison below for how the fee compares with a single-element extension.