£54k–£72k guideDormer
The most popular conversion we build. A flat-roof dormer extends out from the rear slope of the roof, giving you full head height across most of the new room, and usually falls under permitted development.
Loft conversions · London, Kent & Essex
The extra bedroom is already there. It's your loft.
Director-led loft conversions, quoted line by line before a single tile moves. Jason Berry prices the job and builds it. Most come in between £54,000 and £90,000, including VAT.
Your detailed quotation
Priced line by line, before you commit
Jason Berry replies the same working day · Free site visit, no obligation
Bishop's Stortford
Dormer loft conversion
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
Loft Conversions
Turn dead roof space into the most valuable room in the house
A well-built loft conversion adds a bedroom, a bathroom and serious value, without losing an inch of garden. Because the roof structure is already there, it's usually the quickest way to add a proper room to the house, and among the most cost-effective.
Every conversion is designed around your actual roofline and head height, not squeezed into a standard template. Jason surveys the loft himself, tells you honestly what will and won't work up there, and prices the whole job in an itemised quotation before you commit.
The maths of moving vs converting
Moving house
- Stamp duty on the next house
- Estate agent and legal fees
- Removals, surveys and months of upheaval
- Paying a premium for a bedroom your roof already has
£30,000+ spent, none of it on your home
Converting the loft
- The structure is already there, above your head
- Not an inch of garden lost
- The quickest way to add a bedroom and bathroom
- Value added typically exceeds the build cost
An extra storey, same address
Stay put. Build better.
Get your itemised quoteTypes of build
Which loft conversion suits your roof?
The right conversion depends on your roof shape, head height and budget. These are the four we build, with honest guide prices. Jason tells you at the first visit which one your roof will actually take.
£54k–£72k guide
£60k–£82k guideHip-to-gable
Built for semis and end-of-terrace homes with a hipped (sloping) side roof. We build the side wall up into a vertical gable, often paired with a rear dormer, to unlock loft space a hipped roof wastes.
£72k–£90k guideMansard
The maximum-space option, common on period terraces. The whole rear slope is rebuilt at a near-vertical angle, effectively adding a full extra storey. Usually needs planning permission, which we'll guide you through.
£54k–£66k guideVelux / rooflight
If your loft already has generous head height, rooflights and a proper staircase may be all it needs. No change to the roofline, no planning permission in most cases, and the quickest build of the four.
Not sure which one your home needs?
Ask Jason Berry at a free site visitCost, in the open
What a loft conversion really costs
£54,000£90,000
Most loft conversions we build, full build cost
Most loft conversions we build come in between £54,000 and £90,000 including VAT, depending on the type, the size of your roof and the specification you choose. You'll know your exact figure before work starts, and every J.Berry quotation is itemised line by line, so you can see exactly where the money goes.
J.BERRY
Sample quotation
- Full structural work: steels, floor joists and building regs complianceIncluded
- Dormer or roof alterations, tiling and weatherproofingIncluded
- Staircase design and installationIncluded
- First and second fix electrics and plumbingIncluded
- 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 loft conversions
Built by Jason and his team
E18Loft conversion
South Woodford
Bedroom suite with walk-in shower room, dressing area and full-length built-in wardrobes.
CM23Dormer loft conversion
Bishop's Stortford
Contemporary clad dormer with glass Juliet balconies.
The person you deal with
Your loft conversion, run by the director. Not handed to a foreman.
Jason surveys every loft himself, prices every quotation and runs every build to handover. Across 15 to 20 projects a year he's on each one, so when you call, you reach the person who priced your job and is up 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 out, gets up into the loft, checks your head height and roof structure, and tells you honestly which conversion your roof will take, or if it won't.
Detailed quotation
The whole conversion priced line by line, covering structure, staircase, dormer or gable work, bathroom and finishes. A fixed price, not an estimate.
The build
Agreed start and finish dates, Jason running it day to day. Most of the work is above you, so most clients carry on living in the house throughout.
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
“J Berry Construction supplied a comprehensive and detailed quote, which was very competitive. The work was carried out to a very high standard.”
Kevin G, Bishop's Stortford
Rear extension, loft conversion and full remodel
Detailed quotation
Common questions
Loft conversion questions, answered straight
The questions every loft conversion 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 loft conversions we build come in between £54,000 and £90,000 including VAT. A rear dormer with a bedroom and en-suite typically sits in the middle of that range, a Velux conversion less, a full mansard more. You'll get an exact itemised figure before work starts, and unless you change the scope mid-build, that's the figure you pay.
Usually not. Most dormer, hip-to-gable and Velux conversions fall under permitted development rights, so no planning application is needed. Mansards and homes in conservation areas are the main exceptions. Jason will tell you where you stand at the first site visit, before you spend anything.
The main test is head height, around 2.2m from the top of the ceiling joists to the ridge is the usual benchmark. Roof shape and the position of the stairs matter too. Jason measures all of this at the first visit and will tell you straight if a conversion doesn't make sense for your roof.
Typically 8–12 weeks on site. We agree the schedule with you before we start, and keeping to it is part of the deal. Most of the structural work happens from outside via scaffolding, so disruption inside your home is kept to a minimum until the staircase goes in.
No. Almost all of our clients stay at home throughout. The loft is sealed off from the rest of the house and accessed externally for most of the build, the messiest day is usually when the new staircase is cut through, and we plan that with you in advance.
Where we build
Loft conversions across London, Kent and Essex
Based in Sawbridgeworth, Hertfordshire (CM21), close enough for a site visit within days, not weeks. We also have dedicated loft conversion pages for the areas and towns we work in most:
Start your loft conversion
Get your detailed quotation
Tell us about your loft conversion 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.