£66k–£102k guideSingle-storey rear
The classic open-plan kitchen-diner. We extend into the garden, open the back of the house with bifold or sliding doors, and bring light deep into the plan with rooflights. Most fall under permitted development.
House extensions · London, Kent & Essex
The kitchen you actually want, without moving house
Director-led house extensions, itemised line by line before work starts. Jason Berry prices the job and builds it. Most come in between £66,000 and £144,000, including VAT.
Your detailed quotation
Priced line by line, before you commit
Jason Berry replies the same working day · Free site visit, no obligation
Essex
Rear extension
Detailed quotations
Itemised before work starts
The price we quote
is the price you pay
Director-led
Every project overseen by Jason Berry
On schedule
Agreed timeline, kept
House Extensions
More space, more light, more value, on the home you already love
Moving costs tens of thousands in stamp duty, agent fees and upheaval, and you still might not get the kitchen you're after. A well-planned extension gives you that space on the plot you already own, and done properly it adds more to the house than it costs to build.
J.Berry builds extensions and loft conversions, nothing else. Jason visits personally, works out what's possible for your home and budget, and prices the whole job line by line. Then he builds it, on site day to day, one point of contact from first visit to handover.
The maths of moving vs extending
Moving house
- Stamp duty on the next house
- Estate agent and legal fees
- Removals, surveys and months of upheaval
- And the new kitchen still isn't yours
£30,000+ spent, zero space gained
Extending
- Every pound goes into your own home
- No chain, no gamble on a new street
- Designed around how you actually live
- Value added typically exceeds the build cost
More home, same address
Stay put. Build better.
Get your itemised quoteTypes of build
Which extension fits your home?
Four shapes cover almost every home we work on. The guide prices below are for the full build, structure, glazing, first and second fix, finished to a plastered standard, so you're comparing like for like, not one builder's shell against another's finish.
£66k–£102k guide
£108k–£144k guideDouble-storey
The best cost per square metre of any extension, because the foundations and roof are shared across two floors. A bigger kitchen below, an extra bedroom or bathroom above. Needs planning permission, which we'll guide you through.
£90k–£132k guideWraparound
A rear and side-return extension combined into one L-shaped space. The biggest transformation you can make to the ground floor of a terraced or semi-detached home, one large, light room across the full width.
£66k–£90k guideSide return
The Victorian terrace favourite. That dark alley beside your kitchen becomes part of the room, a modest footprint gain that completely changes how the kitchen feels, especially with a glazed roof over the new space.
Not sure which one your home needs?
Ask Jason Berry at a free site visitCost, in the open
What an extension really costs
£66,000£144,000
Most extensions we build, full build cost
Most extensions we build come in between £66,000 and £144,000 including VAT, depending on size, whether it's one storey or two, and the specification of glazing and finishes. Before work starts you'll have an itemised quotation showing exactly where every pound goes, never a vague day rate or a moving target.
J.BERRY
Sample quotation
- Groundworks, foundations and all structural work including steelsIncluded
- Roofing, glazing, bifold or sliding doors and rooflightsIncluded
- First and second fix electrics and plumbingIncluded
- Underfloor heating where specifiedIncluded
- Plastering and insulation to current regs (decoration priced separately if you'd like us to handle it)Included
- A build schedule with a start date and a finish date, agreed before we beginIncluded
The price we quote
is the price you pay
Recent extensions
Built by Jason and his team
SG13Rear extension
Hertford Heath
Full-width single-storey rear extension with sliding doors opening to the patio, and an open-plan kitchen-diner inside.
CM21Orangery-style extension
High Wych, Hertfordshire
Glazed extension to a period flint property.
The person you deal with
Your extension, run by the director. Not handed to a foreman.
Jason surveys every extension, prices every quotation and runs every build to handover himself. Across 15 to 20 projects a year he's on each one, so when you call, you're talking to the person who priced your job and is standing on your scaffold. Not a call centre, not a manager you've never met.
How it works
From first visit to handover
The same four steps on every project, run by the same person.
Site visit
Jason comes to your home, measures up and talks through what your plot and budget will actually take, whether that's single storey, double, wraparound or side return.
Detailed quotation
The whole build priced line by line, covering groundworks, structure, glazing and finishes. A fixed price you can compare properly, not an estimate.
The build
Agreed start and finish dates, Jason running it day to day. Most clients stay in the house while the extension goes up.
Handover
Snagged, signed off together and backed by a 10-year guarantee. The figure quoted is the figure paid.
Tell your story
In our clients’ words
“From the moment he arrived he had a real professionalism and vision for what we could achieve. Jason was trustworthy and honest which made the whole build a pleasure.”
Kim and Tony, Ongar
Full house extension
Director-led
Common questions
Extension questions, answered straight
The questions every extension client asks Jason Berry at the first site visit.
Anything else? Call 07477 707845 and you’ll speak to Jason Berry, not a call centre.
Most extensions we build come in between £66,000 and £144,000 including VAT. A straightforward single-storey rear sits at the lower end, a double-storey or large wraparound toward the top. Every quotation is for the full job to a plastered finish, with kitchens included where you'd like us to supply them. You'll get the exact itemised figure before work starts, and unless you change the scope, that's what you pay.
Many single-storey rear and side-return extensions fall under permitted development rights, so no planning application is needed. Double-storey extensions and larger schemes usually do need permission. Jason will tell you where you stand at the first site visit, and we'll point you to the right people for drawings and applications.
Typically 10–16 weeks on site depending on size and complexity. We agree the schedule with you before we start, and keeping to it is part of the deal, not a nice-to-have.
Yes, nearly all of our clients do. We seal the work area off from the rest of the house and keep water and electrics running to your kitchen for as long as physically possible. The few days where disruption is unavoidable, we plan with you in advance.
A well-built kitchen extension is consistently one of the highest-value improvements you can make, agents typically value the added space at more than a properly priced build costs. More importantly, you get a home that works for how you actually live, without moving.
Where we build
House extensions across London, Kent and Essex
Based in Sawbridgeworth, Hertfordshire (CM21), close enough for a site visit within days, not weeks. We also have dedicated extension pages for the areas and towns we work in most:
Start your extension
Get your detailed quotation
Tell us about your extension and Jason Berry calls you back, usually the same working day. Covering London, Kent and Essex. A name, a number and a postcode is all we need to start.