
Professional House Extension Solutions for Welwyn Garden City Residents
Transform your Welwyn Garden City home with our professional house extension services. Our qualified architects combine local knowledge with innovative design to create extensions that perfectly complement your existing property while maximizing space and value. Whether you're planning a rear extension, side extension, or loft conversion, our Welwyn Garden City team delivers exceptional results that exceed expectations.

A recent extension project in the Welwyn Hatfield area
Having worked extensively in Welwyn Garden City and the surrounding Enfield area, our architects possess deep understanding of local planning requirements, building regulations, and architectural styles. This local knowledge enables us to provide accurate advice, realistic timelines, and cost-effective solutions tailored specifically for Welwyn Garden City projects. We stay current with evolving planning policies and building regulations, ensuring your project meets all current requirements.
Our Welwyn Garden City team ensures your house extension project complies with all current planning policies and building regulations. We understand Enfield Council's specific requirements and can advise on the most appropriate approach for your project. From permitted development rights to full planning applications, we provide comprehensive support to ensure regulatory compliance while maximizing your development potential.
Welwyn Garden City has a diverse housing stock and we have experience extending all property types in the area. Our architects adapt designs to suit the character and structure of each home, whether that means matching original brickwork on a period property or creating a contemporary contrast on a more modern home.
Tell us about your project and get expert advice within 24 hours.
Get a Free QuoteCall 020 3051 9430Mon–Fri: 9am–5pm
Free site visit & consultation
No obligation quote
Covering AL7 & surrounding postcodes
Guide prices for house extensions in the Welwyn Hatfield area. Every project is different — we provide a detailed, itemised quote after a free site visit.
| Extension Type | Typical Cost |
|---|---|
| Single Storey Rear Extension | £30k – £60k |
| Double Storey Extension | £47k – £102k |
| Side Return Extension | £21k – £43k |
| Wrap-Around Extension | £51k – £111k |
| Loft Conversion (Dormer) | £34k – £55k |
| Kitchen Extension | £26k – £51k |
| Basement Conversion | £68k – £170k |
| Garage Conversion | £13k – £26k |
Prices are guide figures for 2026 based on projects in the Hertfordshire area. PD = Permitted Development (no formal planning application needed in most cases). Actual costs depend on specification, site conditions, and scope.

Professional single storey extension design and planning for ground floor expansions
Typical: 6-12 weeks
Two-storey home extension design maximizing space and value
Typical: 8-16 weeks
Garden-facing extensions creating seamless indoor-outdoor living
Typical: 6-10 weeks
Narrow extensions utilizing side garden space efficiently
Typical: 6-12 weeks
Specialized kitchen and dining space extensions for modern living
Typical: 8-14 weeks
Converting attic space into valuable living areas
Typical: 6-10 weeks
Underground extensions creating additional living space
Typical: 12-20 weeks
Expert guidance through planning applications and permitted development
Typical: 8-16 weeks
Comprehensive extensions combining rear and side elements for maximum space
Typical: 10-18 weeks
Comprehensive whole-house renovation and modernization services
Typical: 12-24 weeks
Expert structural engineering services including underpinning and load-bearing work
Typical: 8-16 weeks
Converting garages into functional living spaces for bedrooms, offices, and studios
Typical: 4-8 weeksFrom the first phone call to moving into your new space — here is what to expect at every stage.
We visit your Welwyn Garden City property, discuss your vision, assess feasibility, and give you honest guidance on costs and planning routes.
Our architects create detailed plans, 3D visuals, and construction drawings tailored to your Welwyn Garden City home and how you want to live in it.
We prepare and submit your planning application, liaise with the local authority covering Welwyn Garden City, and handle building regulations documentation.
Our vetted builders bring the design to life. We oversee the build, conduct regular site visits, and manage quality at every stage.
Final inspections, building control sign-off, snagging checks, and handover — your new Welwyn Garden City space is ready to enjoy.
For residential projects in Welwyn Garden City, we offer comprehensive extension services including house extensions, loft conversions, garage conversions, and wrap-around extensions. Our designs maximize space and value while respecting the local built environment. We use the latest CAD software and 3D visualization techniques to help you visualize your project before construction begins.
Whether your Welwyn Garden City project requires planning permission or falls under permitted development rights, our team provides expert guidance and support. We understand Enfield Council's specific requirements and can advise on the most appropriate approach for your extension project. Our comprehensive planning services ensure your project progresses smoothly through the approval process.

Extension completed in the Welwyn Hatfield area
Building control compliance is essential for all construction projects in Welwyn Garden City. Our team provides comprehensive building control drawings and applications, ensuring your project meets all structural, fire safety, and accessibility requirements. We work closely with building control officers to ensure smooth approval processes and compliance with current building regulations.
Our Welwyn Garden City clients benefit from our extensive local knowledge, established relationships with planning authorities and contractors, and commitment to delivering exceptional results. We take pride in our ability to transform client visions into reality while respecting local character and meeting regulatory requirements. We offer competitive rates, transparent pricing, and flexible service packages tailored to your specific needs.

Everything you need to know about loft conversions in London in 2026. Dormer, hip-to-gable, mansard and L-shaped options explained with costs, timelines and planning permission guidance.

Plan your dream kitchen extension in London. Explore side-return, rear and wrap-around options with 2026 costs, planning tips and design inspiration for every budget.

Updated 2026 price guide for house extensions across London. Costs for single storey, double storey, loft conversions and more — broken down by area and project type.
Transform your Welwyn Garden City home with our professional extension services. Contact us today for a free consultation and discover how we can help you create the perfect extension for your property. Our experienced team combines local knowledge with innovative design to deliver exceptional results that enhance your home's value and living space.
Discover our comprehensive range of house extension solutions in London and surrounding areas
Professional single storey extension design and planning for ground floor expansions
Two-storey home extension design maximizing space and value
Garden-facing extensions creating seamless indoor-outdoor living
Narrow extensions utilizing side garden space efficiently
Specialized kitchen and dining space extensions for modern living
Converting attic space into valuable living areas
Call now to speak with our expert team. Get instant responses and professional guidance for your extension project.