Extensions & Projects · Essex & East London
The single biggest transformation available to a Victorian or Edwardian terrace or semi. Filling in the side return and extending the rear together turns three cramped, disconnected rooms into one wide, light-filled kitchen-diner — and very often adds more usable space than any other single move.
Types
Which one suits you depends on whether your house has a side return at all, and how much of the ground floor you want to open up.
Fills in the narrow return beside the kitchen without extending the rear. The smallest move, and the one most likely to stay within permitted development.
The full L-shaped move: side return and rear extension joined into one continuous space. The most common and most transformative option.
Rear extension across the whole width of the house plus the side return, for the largest single-storey footprint available.
The same L-shaped footprint taken up to first floor as well, adding a bedroom or two above the new kitchen-diner.
For houses without a clear existing side return, or where the best configuration isn't obvious yet.
| Extension type | Build cost | Time on site | Planning | Best suited to |
|---|---|---|---|---|
| Side-return only | £2,400–£3,000 /m² | 8–12 weeks on site | Usually permitted development | Terraces and semis with a return |
| Wraparound (side + rear) | £2,500–£3,300 /m² | 14–20 weeks on site | Planning permission required | Terraces and semis with a return |
| Full-width rear with side infill | £2,600–£3,400 /m² | 16–22 weeks on site | Planning permission required | Wide-fronted terraces and semis |
| Double-height wraparound | £2,800–£3,600 /m² | 20–28 weeks on site | Planning permission required | Terraces and semis with a return |
| Mixed or unsure | £2,400–£3,200 /m² | 12–18 weeks on site | Depends on scope | Semis without a side return |
Costs
We don't build, and we take no margin on the build, so we've no reason to flatter these numbers. They are what Essex builders are quoting our clients in 2026.
Typical wraparound extension
£2,500–£3,300 /m²
Around £75,000–£99,000 for a typical 30 m² wraparound (side return plus rear), built to a good standard.
These figures are build cost only.
Ask three builders and you'll get three numbers. What matters is they're pricing the same specification. That is exactly what a proper technical package gives you.
Costs reviewed August 2026 · next review February 2027
What kind of home is it?
Detached
Semi-detached
Terraced
Bungalow
Our design fee
Not an hourly rate and not a percentage of the build. One figure covering survey, concept design, the planning application and the Building Regulations package, quoted after our first conversation.
Use the design cost calculatorWe price-check builders' quotes against the drawn specification and inspect work as it progresses. You don't have to take our drawings and go it alone.
Stage 5 · construction supportPlanning
The side-return element on its own can sometimes be permitted development. The moment it wraps around to join a rear extension, it's treated as one continuous structure and almost always needs full planning.
Wraparounds are treated as one continuous extension, not two separate permitted-development moves. Combining a side return with a rear extension almost always pushes the project over permitted development limits and into a full planning application - factor that into your timeline from day one.
Building Regulations
A wraparound is a single continuous roof over an L-shaped plan, which needs more careful structural thinking than a simple rear extension alone.
New footings tie into the existing side and rear walls, sized for the ground conditions along the whole run.
A long flat or pitched roof over an L-shaped plan needs careful steel sizing — usually more than a simple rear extension alone.
Continuous insulation and glazing strategy across the full wraparound, so the extension performs as one space, not two.
Junctions between the old side-return brickwork and the new rear structure detailed to avoid damp and cold bridging.
The NSP Stages
Click into any stage for what happens, what you receive, and what comes next.
We look at the house, the plot and your budget, and tell you honestly what's achievable before you spend anything.
We measure the property properly. Everything after this depends on the existing drawings being right.
Options on the table: how the side return and rear extension join, roof form, and where the glazing goes.
The full application this project type needs, prepared, submitted and managed through to decision.
Our work
Every project starts as a drawing. These are ours: the plans, elevations and approvals behind the finished rooms.
Add gallery items to show project photos and drawing sheets here.
FAQs
A side-return extension fills in just the narrow strip beside the house. A wraparound joins that side infill to a rear extension, forming one continuous L-shaped space. Wraparounds add more floor area but are more likely to need full planning permission.
Almost always, yes. Even though a side-return infill alone can sometimes be permitted development, wrapping it around to meet a rear extension is treated as one continuous extension and typically exceeds the depth limits permitted development allows.
These houses typically have a narrow side return next to the kitchen that's dead space, and a small rear addition already. Joining the two is often the single most effective way to create one wide, light-filled kitchen-diner without losing garden.
Less than most people expect - the side return itself isn't garden, and the rear element is usually similar in depth to what permitted development would allow anyway. We model this at feasibility stage so you know exactly what you're trading.
Very likely, since the side infill sits directly against your neighbour's boundary wall. We flag this early and can point you to surveyors we work with regularly.
Typically 10 to 16 weeks for planning and Building Regulations drawings, then 14 to 20 weeks on site for the build itself.
Yes, and some clients do exactly that to spread cost. Just be aware that doing them separately may mean the side-return phase can be permitted development, while the later rear phase still needs its own planning route.
We work to a fixed fee agreed before we start. Use the cost calculator for an indicative range for a wraparound specifically.