How much does a London
loft conversion cost?
2026 prices, by type.
Velux, rear dormer, L-shape, hip-to-gable or mansard — the real figures we use on client quotes across Fulham, Battersea, Chiswick and beyond. Sixty-second calculator. No callback.
Pick your roof. See the price.
All figures inclusive of design, planning, build, contingency and VAT. Tighter numbers for your postcode and spec live inside the calculator.
The line-by-line breakdown for a London dormer.
Worked example for a typical £100k rear dormer with double bedroom and en-suite in a SW6 or SW11 postcode. Every 2VP project gets a line-by-line bill of quantities — never a one-page lump sum.
Most London loft conversions don’t need planning.
Here’s how to tell.
Permitted development (PD)
Covers most rear dormers and hip-to-gable conversions in non-protected areas, provided you stay within 40 m³ added volume (terrace) or 50 m³ (semi/detached), don’t raise the ridge, and use matching materials. We’ll check your address before quoting.
Best for: standard Victorian rear dormers outside conservation areas.
Full planning permission
Required for all mansards, all conservation areas, all Article 4 zones, anything over PD volume limits, and anything that materially changes the front roofline. Worth the time — opens up far better design.
Best for: mansards, period houses in SW3/SW6/W11, premium specifications.
Building regulations
Even when you don’t need planning, you always need building regulations sign-off — fire escape route, staircase headroom (2m minimum), structural calcs, thermal insulation to current standards.
Required for: every loft conversion, full stop.
The 2026 London Loft Cost Guide.
Twenty-four pages of real cost data from our client lofts across SW6, SW3, W11, SW11 and W4. Straight to your inbox.
- ✓Velux, dormer, L-shape, hip-to-gable & mansard side by side
- ✓£100k dormer cost breakdown, line by line
- ✓Borough multipliers — Zone 1 vs Zone 2 vs Zone 3
- ✓PD vs full planning — the volume calculations explained
- ✓Building regs essentials (headroom, fire escape, stairs)
- ✓How to maximise property value uplift on a London loft
Send me the guide.
What homeowners ask us before they book.
How much does a loft conversion cost in London in 2026?
Typical 2026 London ranges (inc. design, build, contingency & VAT): Velux conversions £45k–£75k; rear dormers £75k–£120k; L-shape dormers £95k–£150k; hip-to-gable + rear dormer £110k–£170k; mansards £130k–£220k. Postcode (Zone 1 vs Zone 3), specification tier and structural complexity move you within the range.
What's the cost per m² for a London loft conversion?
Roughly £2,400–£4,600 per m² turnkey depending on type. Velux conversions are the cheapest per m² because the roof structure stays in place. Mansards are the most expensive because the entire rear roof is rebuilt. The calculator gives you a tailored £/m² number based on your postcode and spec.
Do I need planning permission for a loft conversion?
Most London loft conversions fall under permitted development (PD): rear dormers and hip-to-gable conversions are usually allowed without planning if you stay within 40m³ added volume (terrace) or 50m³ (semi/detached), don't raise the ridge, and match existing materials. Mansards always need full planning permission. Conservation areas and Article 4 directions remove PD rights entirely.
How long does a loft conversion take?
Allow 6–10 weeks for design and planning (longer for mansards), then 8–14 weeks on site for a standard dormer, 12–18 weeks for an L-shape or hip-to-gable, and 14–20 weeks for a mansard. Most of the work is external — your house stays liveable throughout except for the final week when the staircase goes in.
Will a loft conversion add value to my London house?
Yes — typically 15–25% on the property value in central and inner-west London, often more in prime postcodes. A well-designed loft with a double bedroom + en-suite usually returns 130–200% of the build cost on resale. ROI is highest on dormers (best floor area per £) and lowest on Velux-only (limited headroom).
What's the minimum head height I need to convert my loft?
You need at least 2.2–2.4m head height from the existing ceiling joists to the underside of the ridge for a meaningful conversion. Less than that and you're looking at a roof raise (which loses PD rights) or a mansard. We measure on the free site visit — most Victorian and Edwardian London houses have enough.
Will my neighbours have a say? What about party wall?
If you're building on or near the boundary line, or cutting into a shared party wall to insert steels, you need a Party Wall Award under the 1996 Act. We serve notice on your behalf and the typical timeline is 4–8 weeks. Each neighbour appoints their own surveyor — fees usually £1,000–£3,000 per agreement and are your cost.
Can I stay in the house during the build?
Yes, almost always. Loft conversions are predominantly external works — scaffolding goes up, the roof is opened from above, and the staircase is installed last. You'll have a noisy fortnight when the dormer is framed and a dusty week when the stairs go in, but you don't need to move out.
Loft conversion cost in 60 London areas.
Twenty minutes with Nick Elias RIBA.
On us.
Bring your floorplan or roof photo. Walk out with a feasibility verdict (head height, PD vs planning, structural route), realistic budget and a programme — even if a loft isn’t the right move for your house.
Studio at 20 Dawes Road SW6, video call, or on site.
One number. Sixty seconds. No callback.
Price your loft using the same 2026 rate card we quote real clients with.
Price my loft →The home you actually want, finished on the date in the contract — and you watch every day of it happen from your phone.
- Your number in 60 seconds
- Itemised stage breakdown in 2 minutes
- Survey within 7 days
You answer 3 questions. We do the drawings, planning, party wall, trades and snagging.
- 10% to mobilise, then weekly against work already done — with 5% held past handover: 2.5% released at practical completion and 2.5% at the end of the 12-month defects period
- £550 survey fee credited in full against your contract
- Every variation priced and signed before a penny is spent
The date is a term of the contract. We finish on the agreed date, or we pay you £500 for every week we are late.
4.8 from 16 Google reviews
Every review is published in full on our reviews page, including the one-star. Google is the only platform we quote a rating for, because it is the only one we can evidence.
As a structural engineer, I've collaborated with 2VP Projects Ltd on several residential projects in London. Their attention to detail, proactive site management, and clear communication make every stage—from design to execution—smooth and efficient. It's rare to find a contractor who values both precision and professionalism at this level. A truly reliable partner.
Great company to work with. Professional, reliable and easy to deal with. Vladimir and the team are always responsive, straightforward and genuinely care about doing things properly. I've had a very positive experience working with 2VP and would happily recommend them.
Extension went smoothly from start to finish. Communication was great throughout, and the team delivered exactly what we asked for. Thank you, 2VP!
What is covered, and by whom
A builder’s own guarantee is worth exactly as much as the company standing behind it. Here is what comes as standard, what you can add, and what has to come from somebody other than us — set out in full on our insurance and guarantee page.
- 12-month workmanship warranty on second-fix fittings
- £5M public liability
- £10M employer's liability
- £2M professional indemnity
- HomePro insurance-backed guarantee, 10 years
- Priced at 2.5% of the contract sum
- Underwritten by an insurer, so it survives us
- 10-year structural warranty on a new dwelling (NHBC / LABC / Premier)
- Professional fees — architect, engineer, building control
- We will tell you when you need one rather than let you find out