£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 · Hertfordshire & 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.
Every conversion is fully insured and backed by our 10-year guarantee.
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CheckatradeYour detailed quotation
Priced line by line, before you commit
- Jason Berry replies the same working day · Free site visit
- Over 100 conversions completed
- Fully insured · 10-year guarantee
Bishop's Stortford
Dormer loft conversion
- Over 100 loft conversions completed
- Fully insured · 10-year guarantee
- 10% deposit, then stages as work completes
GoogleCheckatradeLoft 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.
Read the full loft conversion cost guide
You never pay ahead of the work
A 10% deposit books your slot. After that you pay in stages as the build progresses, so your money always follows completed work, never the other way round.
- Over 100 loft conversions completed
- Fully insured · 10-year guarantee
- 10% deposit, then stages as work completes
GoogleCheckatradeEvery conversion is fully insured and backed by our 10-year guarantee.
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
Genuine J.Berry loft work, before and after. Drag the slider to compare. More added as each job is photographed.
Roof re-cover and rear dormer
100+
Loft conversions
completed
Jason and his team
Your loft conversion, run by Jason. Built by the same team, every time.
Jason surveys every loft himself, prices every quotation and is on site through the build, not just at the start and the handover. He works with the same small team of tradesmen year-round, so the people cutting into your roof are the same faces on every J.Berry job, not agency labour that changes week to week. Across 15 to 20 projects a year he's on each one personally, so when you call, you reach the person who priced your job. Not a call centre, not a manager you've never met.
Jason takes on a limited number of conversions each year and prices every one himself. Book your free site visit early to hold a slot.
15–20 projects a year
Same team on every job
10-year guarantee
Every conversion is fully insured and backed by our 10-year guarantee.
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. You never pay ahead of the work: deposit, then stages as the build progresses. The figure quoted is the figure paid.
Tell your story
In our clients’ words
Real clients, with their towns where we have them. More reviews added as they come in.
GoogleCheckatrade“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 07920 731533 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.
Yes. J.Berry is fully insured, and every conversion is backed by our 10-year guarantee. Jason stands behind the work.
A 10% deposit books your slot, then you pay in stages as the work progresses. You are never paying for work that has not been done.
Most of the structural work happens outside via scaffolding, and the loft is sealed off from the rest of the house, so you can carry on living there throughout. The messiest single day is when the new staircase is cut through, and we plan that with you in advance.
Where we build
Loft conversions across Hertfordshire and Essex
Based in Sawbridgeworth, Hertfordshire (CM21), close enough for a site visit within days, not weeks. We build right across Hertfordshire and Essex, from Bishop's Stortford, Hertford, Ware and Hoddesdon to Harlow, Epping, Loughton and the towns between.
Dedicated loft conversion pages for the 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 Hertfordshire and Essex. A name, a number and a postcode is all we need to start.
Every conversion is fully insured and backed by our 10-year guarantee.