London's Trusted Builders

We Build
What Others
Only Promise.

Extensions, loft conversions, full renovations. GroundWork Co. delivers on time, on budget, and built to last — with every project fully warranted.

FMB Registered 10-Year Structural Guarantee All London Boroughs
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Years Trading
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Projects Completed
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On Time & On Budget
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Survey Response
Our Work

Results That Speak

Drag the handle to compare before and after on a selection of recent projects across London.

Before
After
Rear Extension — Islington
6m × 4m kitchen extension 9 weeks
Before
After
Loft Conversion — Hackney
Dormer + en-suite 11 weeks
The Process

From Survey to Handover

No surprises. Every project follows the same clear five-step process so you always know what's happening and when.

01

Free Survey

We visit within 48 hours, assess the site, take measurements and understand your vision.

02

Fixed Quote

Detailed written quote within 5 days. Fixed price — no hidden costs, no surprise invoices.

03

Planning

We handle planning permission and building regulations submissions where required.

04

Build

Weekly progress updates, site foreman on-site daily. You're never in the dark.

05

Handover

Snagging list addressed, building regs sign-off, and your 10-year structural warranty issued.

What We Build

Our Specialisms

General builders with deep expertise across residential extensions, conversions and renovations throughout London.

01

Rear Extensions

Single and double-storey rear extensions. Bi-folds, skylights, structural steel — we design and build the lot.

02

Loft Conversions

Dormer, hip-to-gable, mansard. New bedroom, home office or en-suite — we handle planning and build.

03

Side Returns

Reclaim the dead space beside your kitchen. Side return extensions that transform ground floor living.

04

Garage Conversions

Permitted development, no planning needed in most cases. Habitable room ready in 4–6 weeks.

05

Full Renovations

Strip back to brick and start fresh. Full refurbs managed start to finish with a single fixed quote.

06

New Builds

Plot to completion. We work with architects and structural engineers to deliver standalone new-build homes.

Cost Calculator

What Will It Cost?

Get an indicative price in seconds. We'll confirm exact costs after a free site survey — no obligation.

1 · Choose Your Project

2 · Choose Size

Indicative Cost Range
£25,000 – £45,000

Small rear extension. Actual cost confirmed after free survey.

Typical duration6–9 weeks
Planning requiredUsually no
Survey feeFree
Fixed price quoteYes — guaranteed
Book a Free Survey →

Materials & Trade Partners

Jewson
Travis Perkins
Velux
Knauf
Tarmac
Cemex
Rockwool
British Gypsum
Jeld-Wen
Schiedel
Jewson
Travis Perkins
Velux
Knauf
Tarmac
Cemex
Rockwool
British Gypsum
Jeld-Wen
Schiedel
Client Feedback

Clients Who Stayed in Touch

We're proud that most of our work comes from referrals and repeat clients. Here's what they say.

Rear Extension
"They came in under quote by £3,000 and finished two weeks early. The kitchen extension is stunning — it's completely changed how we use the house."
SR
Sophie Reed
Crouch End, London
Loft Conversion
"Three quotes, GroundWork were mid-range. Chose them for their transparency. Weekly updates, no mess left overnight. We'd use them again without hesitation."
JK
James & Kim Patel
Walthamstow, London
Full Renovation
"Full gut and renovation on a Victorian terrace — structural work, new layout, the works. GroundWork delivered a genuinely beautiful home. Absolutely recommend."
AL
Anna Lawson
Peckham, London

Ready to Build?

Book your free site survey. No obligation, no hard sell — just an honest assessment and a fixed-price quote within 5 days.