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PROJECT №054 · SURREY
Large Double Storey House Extension in Surrey
Fixed
itemised price
10-yr
warranty
HOUSE EXTENSIONS · LOFTS · NEW BUILDS · SINCE 2004
Add space to your home — without managing multiple contractors
House extensions, loft conversions and new builds across South West London & Surrey — with in-house architects, fixed itemised pricing and stage-based payments.
- Fixed itemised quote
- 320+ completed projects
- In-house architects & builders
- £5m insured
Free quote Get instant budget estimate 2 min · online 2 min calculator See projects View recent projects
Calculator gives an instant ballpark range. Fixed itemised quote follows a free 1–2 hour on-site visit.
From £1,800/m²
Transparent itemised pricing
6–14 weeks
Typical extension timeline
10-year warranty
On all structural work
Free quote in 24h
No obligation, no callbacks
New · Online price calculator
Get an instant ballpark in 2 minutes.
A guided 2-minute tool — pick your home, your project type and a few key features. The calculator runs the numbers using real data from 320+ completed builds and shows you a transparent price range straight away.
- ✓ Real prices — Based on 320+ completed projects
- ✓ No callbacks — See your range immediately, no phone tag
- ✓ 100% free — No email gate, no obligation
dpsco.co.uk/calculator ESTIMATE STEP
YOUR ESTIMATE
£72k – £107k
For a 30m² rear extension in SW15 · 10–14 weeks
Architectural & Structural design from £2,500
Building control and Party wall from £1600
Sliding doors/Bifold door from £3,500
Skylight from £800 each
◆ PRICES UPDATED MONTHLY · LAST: MAY 2026
01 · What we do
Three things, done properly.
Not every house needs the same thing. We recommend the option that adds the most usable space, light and resale value for your budget.
HOUSE EXTENSIONS / Service 4 variants
House extensions
A house extension is the biggest investment you can make in your home — it should transform how your family lives, not just add square metres. We design every extension around how you actually use your space, with a fixed, itemised price and stage-based payments so you stay in control from first sketch to handover.
- Single-storey extension
- Double-storey extension
- Side-return extension
- Wrap-around extension
LOFT CONVERSIONS / Service 4 variants
Loft conversions
A loft conversion adds an entire floor without losing any garden. We design lofts as proper rooms — full-height ceilings, generous windows, en-suite bathrooms — not afterthoughts squeezed into the rafters.
- Dormer
- Mansard
- Hip-to-gable
- L-shape
NEW BUILD / Service 4 variants
New builds
New build is the most ambitious thing you can do — a chance to design exactly the home you want from the ground up. We have delivered single houses on infill plots, full plot developments, and demolition + rebuild projects. We work with leading architects or your own.
- Family homes
- Replacement dwellings
- Mews
- Sites up to 4 units
02 · Recent work
Selected projects.
03 · How we work
Five stages, one team.
Every project we deliver runs through the same five stages — consultation, design, planning, build, handover.
01
Free consultation
We visit your home, listen to what you want, and walk through what is possible. We tell you honestly what we think the budget and timeline will be — and what risks to expect.
02
Design
Architectural drawings — plans, sections, elevations — plus 3D visualisations of your future home. We iterate until you love it before any tooling is bought or any wall is touched.
03
Planning permission
We submit your application, manage the council relationship, and respond to any objections. You sign one form; we do the rest — including party-wall agreements with neighbours.
04
Build
Our project manager and site team take over. Weekly progress meetings, transparent stage-based payments, photo updates. You stay informed without being on-site every day.
05
Handover
Snagging, sign-off, certificates, manuals. We are not done until you are completely happy. Then we hand over keys, the maintenance manual and the 10-year warranty.
04 · Client voices
In our clients’ own words.
Verified · Houzz, Google
05 · Where we work
Across South West London.
We know the streets, the planning quirks and the typical property styles of every neighbourhood we work in.
All locationsFollow us on Instagram
From our site, lately.
Progress shots, finished rooms and the occasional behind-the-scenes — straight from the South West London projects we’re running this month.
