House Extensions in Welwyn Garden City & Luton
House Extensions in Welwyn Garden City & Luton
Single Storey · Double Storey · Rear Extensions · Side Return Extensions
Serving Welwyn Garden City, Luton, St Albans & Hitchin · Projects from £5,000
What Is a House Extension?
A house extension is one of the most effective ways to add space, light and long-term value to your property without the cost and disruption of moving home.
Whether you are looking for a single storey rear extension to open up your kitchen and living area, a double storey extension to add bedrooms, or a side return extension to maximise unused space — we design and build extensions that seamlessly blend with your existing property.
We specialise in House Extensions Welwyn Garden City, including rear, side-return, single-storey and double-storey extensions.
We manage the entire build from foundations and steelwork through to plastering, electrics, plumbing and final decoration — one team, one point of contact throughout.
We provide House Extensions Welwyn Garden City services from foundations and structural work through to full interior finishing.
What's Included in a House Extension in Welwyn Garden City
From foundations and steelwork through to plastering, decoration and final fit-out — here is what a typical house extension covers
Design & Planning Advice
We advise on extension design, size and layout to maximise space and comply with permitted development rules
Foundations & Groundwork
Full excavation, concrete foundations and drainage work to the correct depth and specification
Brickwork & Blockwork
External walls built to match your existing property — brick, block or render finish as required
Roof Structure & Tiling
Pitched or flat roof construction including joists, felting, insulation and tiling or membrane finish
Windows & Doors
Supply and installation of windows and doors including bi-fold, French and sliding options
Electrics & Plumbing
Full first and second fix electrics and plumbing including underfloor heating where required
Plastering & Decoration
Internal plastering, skimming and full decoration throughout the new extension
Flooring
Tiling, laminate, engineered wood or carpet fitted to match or complement your existing interior
Project Management
One point of contact throughout — clear communication, realistic timelines and written quotes
Why Choose Master Builder?
- Extensions built to match your existing property — seamless finish guaranteed
- Free site visits and detailed written quotes
- Projects from £5,000 — serious jobs only
- Fully insured — public liability & employers
- Clear communication start to finish
- Covering Welwyn Garden City, Luton, St Albans & Hitchin
What Customers Say About Our Work
House Extension — Project Photos
A selection of our house extension projects across Welwyn Garden City, Luton & surrounding areas
Frequently Asked Questions
Everything you need to know before getting in touch
We build single storey rear extensions, double storey extensions, side return extensions and wraparound extensions. We work with all property types across Welwyn Garden City, Luton, St Albans and Hitchin.
Many single storey rear extensions fall under permitted development and do not require planning permission. Double storey extensions and larger projects typically do require permission. We can advise on this during your initial call and site visit.
Extension costs vary depending on size, specification and finish. We take on extension projects starting from £5,000. Every project receives a detailed written quotation after a free site visit — no obligation.
A typical single storey extension takes 8 to 12 weeks from groundworks to final finish. Double storey extensions can take 12 to 20 weeks depending on complexity. We provide a full timeline in every written quotation.
Yes. We carefully match brickwork, roofline and window styles to your existing property so the extension looks like it was always part of the original build.
Yes. We are direct builders and manage all trades in-house including brickwork, roofing, electrics, plumbing, plastering and decoration. You deal with one team throughout.
In most cases yes. We work cleanly and efficiently to minimise disruption. We will advise during the site visit if any phase of the work requires temporary access restrictions.
Yes. We carry full public liability insurance and employers liability insurance covering all extension work. Documentation is available on request.
- Fully Insured
- Free Site Visits
- 20+ Years Experience
- Projects from £5,000
- Fully Insured
- Free Site Visits
- 20+ Years Experience
- Projects from £5,000
Ready to Start Your House Extension?
Free site visits and detailed written quotes for house extension projects from £5,000. No obligation.