That Narrow Side Return Is the Key to the Whole Ground Floor
Victorian and Edwardian homes are full of character and short on width. The side return, that strip of wasted space beside the kitchen, is the unlock. Wrap it together with a rear extension and the entire back of the house becomes one generous, connected space: kitchen, dining and living opening onto the garden, with glazing that floods it all with light.
A wrap-around is a proper structural project: steels, drainage, party walls and planning all need doing correctly. At Mosaic Bespoke we handle every part of it, and we design the light first, because that is what makes these spaces extraordinary.
As a guide, wrap-around extensions typically cost between £2,200 and £3,200 per square metre, with glazing and structural openings the biggest variables. The calculator below gives you a guide figure for your home.
Planning Permission
Because a wrap-around extends to the side and rear together, it usually needs a full planning application rather than permitted development. We design to what planners approve locally and manage the application for you.
How Long It Takes
Design, planning and pricing typically take 3 to 6 months, and the build itself usually runs 4 to 6 months on site. We keep the rest of the house sealed and liveable while the back is transformed.
Why a Wrap-Around?
It transforms the whole ground floor at once: kitchen, dining and living become one connected space opening onto the garden, rather than a chain of small rooms.
Rooflights over the side return and generous rear glazing bring light deep into homes that were built narrow and dark.
For period properties across Hertfordshire, it is the single most transformative extension there is, and it is exactly the kind of structural project we are built for.
Every project follows the same four-stage process, structured to provide clarity, manage planning risk, and ensure your extension is comprehensively prepared before construction begins.
01
Discover
Opinion of Probable Cost
Understand what your extension is likely to cost before committing further.
02
Define
Feasibility Study
Assess planning risk, structure and budget exposure specific to your home.
03
Prepare
Pre-Construction Agreement
Coordinate design, engineering and cost control before your extension begins on site.
04
Deliver
Construction and Delivery
Build with one accountable, structured team, managed daily from start to handover.
See what your wrap-around extension could cost
What type of extension are you planning?
Choose the option closest to your project.
What size are you thinking?
Approximate internal floor area.
What level of finish are you after?
Think about materials, fittings, and overall ambition.
Where is the project?
Location affects labour and material costs significantly.
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Indicative only. Excludes professional fees, planning costs, VAT, kitchens and bathrooms, and site-specific conditions.
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Do you have planning permission in place?
This is one of the biggest factors in how quickly and confidently we can price your project. Many extensions fall under permitted development, so may not need it at all.
What stage are your drawings at?
Working drawings (full technical detail) allow us to price with much greater precision than planning drawings alone.
Is there anything to demolish or strip out first?
Removing a garage, conservatory or internal walls adds cost and programme time before construction begins.
What is the site access like?
Restricted access can affect how materials are delivered, how plant is brought in, and how long the programme takes.
Have you considered your mechanical & electrical specification?
Smart home systems, EV charging, solar PV, air source heat pumps, and underfloor heating throughout all affect programme and cost.
Do you have a target completion date or timeline in mind?
Understanding your timeline helps us think about programme, procurement, and whether pre-construction work needs to be fast-tracked.
Almost there: unlock your estimate
Enter your name and email below. Your estimate unlocks on screen the moment you submit, we will email you a copy, and our team will be in touch for a no-obligation chat.
Your indicative estimate
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Indicative only. Excludes professional fees, planning costs, VAT, kitchens and bathrooms, and site-specific conditions.
Thank you. A copy is on its way to your inbox, and our team will be in touch by the next working day.
Answer a few quick questions for an instant guide figure. The estimate is based on typical local build costs; for a detailed figure we will arrange a free consultation.
It is a side return extension and a rear extension built as one, wrapping around the back corner of the house in an L shape. It turns a narrow kitchen and wasted side alley into one wide, open-plan space.
Do I need planning permission for a wrap-around extension?
Usually, yes. Combining side and rear typically takes the project beyond permitted development, so a full application is needed. We design to local planning appetite and manage the process for you.
How much does a wrap-around extension cost?
As a guide, between £2,200 and £3,200 per square metre depending on structure, glazing and finish, plus the kitchen itself. Use the calculator above for a figure shaped to your home.
Will I need a party wall agreement?
Almost always. Wrap-arounds are built along the boundary with your neighbour, which brings the Party Wall Act into play. We prepare and serve the notices and manage the agreements as part of the project.
Will it make the middle of the house dark?
Not if it is designed properly. Rooflights over the side return, generous rear glazing and careful room depths keep light reaching deep into the plan. It is the first thing we design for.
Considering a Wrap-Around Extension?
Own a period home with a side return? Our appraisal sets out what the space could become, the planning route and the budget, without obligation.
