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PROJECT №018 · SURREY
Large Double Storey House Extension in Surrey
Fixed
itemised price
10-yr
warranty
House extension builders for South West London & Surrey
Design, planning and construction managed by one in-house team. Receive a detailed, fixed-price quotation after a free site visit — no obligation, stage-based payments, established in 2007.
- Free on-site consultation
- Fixed itemised quotation
- Design, planning + construction
- £5m public liability insurance
Typical projects from £120k+
Transparent itemised pricing
8–16 weeks
Typical extension timeline
10-year warranty
On all structural work
Start your project enquiry
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 – £125k
For a 30m² rear extension in SW15 · 10–14 weeks
Architectural & Structural design from £3500
Building control and Party wall from £1600
Sliding doors/Bifold door from £4500
Skylight from £800 each
◆ PRICES UPDATED MONTHLY · LAST: MAY 2026
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 locations