House Extension Builders in Surrey & Elmbridge
- 30 years experience
- 10-year structural guarantee
- Fixed fee quotation
- 5% Scheduling discount
- 500+ Successful projects
Create more space, light and value with a carefully planned house extension from one accountable design and build team.
House extension builders for Surrey family homes
A well-designed house extension is one of the most effective ways to improve how your home works without moving. For many properties in Elmbridge, East Molesey, Esher, Kingston upon Thames, Surbiton and nearby Surrey towns, a carefully planned extension can create a brighter kitchen, open-plan living space, extra bedrooms, better utility space or a stronger connection to the garden.
HWP Design & Build delivers single-storey extensions, double-storey extensions, rear extensions, side return extensions, wrap-around extensions, kitchen extensions and garage conversions. We help you choose the right route for your property, plot, planning position, budget and long-term use of the new space.
Extension projects need more than attractive finishes. They need sound structure, compliant foundations, practical drainage, insulation, ventilation, weatherproofing, Building Regulations, careful sequencing and clear documentation. We manage Building Regulations, site coordination and finish quality as part of a complete service. If you are ready to explore your options, request a fixed-price quotation or view our recent projects.
Clear scope, guaranteed workmanship and local accountability
HWP Design & Build is the trading name of SMA Design & Build Ltd. We combine over 30 years of hands-on industry experience with fixed-price quotation clarity, insured project delivery and aftercare support.
Learn more about our accreditations, insurance and guarantees, our design and build process and our customer reviews.
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House extensions in Surrey:
HWP Design & Build provides rear, side return, wrap-around, kitchen, single-storey, double-storey and garage conversion projects across Surrey, Elmbridge and nearby South West London. We assess the property, structure, ground conditions, drainage, access, planning, Building Regulations and finish specification before preparing a fixed-price quotation.
Common house extension types
Different extension types solve different layout problems. We explain the practical trade-offs clearly so you can balance space, budget, planning risk, finish quality and disruption before committing to a route.
Which house extension is right for my Surrey home?
The right extension depends on your plot, existing layout, roof design, boundary position, planning constraints and how you want to use the new space. A rear extension may be enough to create a brighter kitchen and family area, while a side return or wrap-around extension can reshape the whole ground floor. Double-storey extensions can add bedrooms and bathrooms as well as living space, while garage conversions can unlock existing floor area with less external change.
During the survey stage, we explain which options are realistic for your property and which route offers the best balance of space, cost, planning risk and long-term value.
| Extension type | Best suited to | Typical benefit |
|---|---|---|
| 1 Single-storey extension | Homes needing more ground-floor living, kitchen or dining space. | A practical way to improve flow, daylight and connection to the garden. |
| 2 Rear extension | Properties with enough garden depth behind the existing house. | Opens up the back of the home for kitchen, dining and family living. |
| 3 Side return extension | Victorian, Edwardian and terrace-style homes with narrow side space. | Adds width and light where the existing ground-floor layout feels restricted. |
| 4 Wrap-around extension | Homes where a combined rear and side extension will unlock the ground floor. | Creates a more transformative kitchen, dining, living and utility layout. |
| 5 Double-storey extension | Homes needing extra bedrooms or bathrooms as well as downstairs space. | Adds accommodation on two floors and can improve long-term family flexibility. |
| 6 Kitchen extension | Families wanting a larger kitchen, dining, entertaining and everyday living area. | Creates the open, practical heart of the home with better light and storage. |
| 7 Garage conversion | Homes with underused garage space that can be converted into accommodation. | Adds usable room area with fewer external changes than many extensions. |
How much does a house extension cost in Surrey?
House extension cost varies significantly because no two homes, plots or specifications are the same. A simple rear extension with modest finishes is very different from a wrap-around kitchen extension with steelwork, roof glazing, drainage alterations, underfloor heating, premium glazing and whole-ground-floor refurbishment.
Rather than publish a misleading headline price, we provide fixed-price clarity after reviewing the property, design, structure, approvals route and level of finish required. This helps avoid the common problem of comparing quotations that include different assumptions.
| Cost factor | Why it affects the quotation |
|---|---|
| Extension type | Rear and single-storey extensions are often simpler than wrap-around or double-storey extensions with more structural and planning complexity. |
| Foundations and ground conditions | Soil, trees, existing drainage, nearby structures and foundation depth can all affect engineering and build cost. |
| Structural openings | Large openings between the existing house and the extension usually require steelwork, temporary works and careful sequencing. |
| Glazing and roof design | Sliding doors, roof lanterns, rooflights, flat roofs, pitched roofs and bespoke glazing all change cost and performance. |
| Kitchens, bathrooms and utilities | New kitchens, utility rooms, WC facilities and drainage changes add services, finishes and coordination requirements. |
| Finish specification | Flooring, joinery, heating, lighting, decorating, kitchen products, storage and exterior finishes can significantly affect the final price. |
Local knowledge matters because house extensions around Elmbridge, East Molesey, Surbiton, Thames Ditton, Esher and Kingston often involve established housing stock, tight access, neighbouring properties, party wall matters, drainage constraints and planning sensitivities that need careful feasibility checks before work begins.
The most expensive parts of a house extension are usually foundations, drainage, structural steelwork, roof design, glazing, kitchen specification, heating, electrics and internal finishes. For a deeper budget overview, read our Surrey house extension cost guide or our Elmbridge house extension costs, planning and timeline guide.
What happens after you request a house extension quotation?
We review your enquiry, arrange a suitable time to discuss the property, then assess layout, access, structure, planning route, Building Regulations, likely disruption and the level of finish required before preparing a clear scope.
Start your extension enquiryLocal extension considerations in Elmbridge and Surrey
House extensions around East Molesey, Esher, Thames Ditton, Claygate, Surbiton and Kingston often involve established housing stock, neighbouring boundaries, drainage routes, mature trees, restricted side access and planning sensitivity. We review these points early so the design, quotation and programme are based on the actual property rather than a generic extension model.
| Area | Common extension consideration | How we approach it |
|---|---|---|
| East Molesey / West Molesey | Rear extensions, kitchen extensions, shared boundaries and family-layout upgrades. | Early review of access, drainage, party wall position and garden connection. |
| Esher / Claygate | Larger detached and semi-detached homes, specification-led projects and planning sensitivity. | Clear feasibility, design coordination and specification-led pricing. |
| Thames Ditton / Long Ditton | Side return, rear and wrap-around layouts where neighbouring properties are close. | Careful boundary, daylight, drainage and construction access planning. |
| Surbiton / Kingston | Victorian, Edwardian and terrace-style homes with layout and party wall constraints. | Practical design around structure, services, neighbours and build sequencing. |
How we deliver your house extension
We start with a survey and feasibility check, then confirm the best route for layout, structure, permissions and build sequencing. Our aim is to give you a clear, buildable scope before work begins.
House extensions across Elmbridge, Surrey and South West London
We are based near the Surrey and London border and regularly support homeowners planning extensions, loft conversions and full home improvements across the local area.
Key locations include East Molesey, West Molesey, Hampton Court, Thames Ditton, Esher, Claygate, Walton-on-Thames, Weybridge, Cobham, Kingston upon Thames, Surbiton, Teddington, Twickenham, Richmond, Wimbledon and nearby South West London.
Recent house extension projects
Explore examples of extension and refurbishment work to see how different property styles, planning constraints and layouts can be approached.
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Useful house extension guides
Related house extension services
Planning a house extension? These related services help with approvals, structure, project coordination and wider home improvement work.
House Extension FAQs for Surrey & Elmbridge Homeowners
House extension cost depends on the size, structure, ground conditions, glazing, kitchen specification, drainage, access, finish level and whether planning, party wall or structural design work is required. We start with a survey and defined scope so your quotation is based on your property, not a generic square-metre estimate.
Yes. We build house extensions across East Molesey, West Molesey, Elmbridge, Esher, Thames Ditton, Hampton Court, Kingston upon Thames, Surbiton, Walton-on-Thames, Weybridge, Cobham and nearby South West London. Our strongest local focus is within around 20 miles of East Molesey KT8.
Sometimes. Many smaller house extensions can fall under permitted development, but this depends on property type, previous extensions, boundary distances, height, materials, conservation context and whether any local restrictions apply. Larger rear, side, wrap-around and two-storey extensions often need a householder planning application. We can review the route and manage applications through our planning permission service.
Yes, most habitable house extensions need Building Regulations approval because foundations, structure, insulation, fire safety, ventilation, drainage, electrics and heating need to comply. We coordinate compliant details, inspections and completion documentation through our Building Regulations support.
You may need Party Wall notices if the extension involves work on or near a shared boundary, excavation close to neighbouring foundations, or structural work affecting a party wall. This is common for side return, rear and wrap-around extensions in tighter Surrey and South West London plots. We can advise through our party wall support service.
Often yes, but it depends on the scale of work, access, services, kitchen disruption and whether major structural openings are being formed. We discuss sequencing, temporary protection, safety, dust control and service interruptions before work starts so you can plan realistically.
Timelines vary by size and complexity. A straightforward single-storey rear extension is usually quicker than a double-storey or wrap-around extension with major structural alterations, kitchen installation and whole-ground-floor refurbishment. We agree a realistic programme before work starts and keep you updated as the build progresses.
The largest cost drivers are often foundations, drainage diversions, steelwork, large glazing systems, roof lanterns, kitchen specification, utility alterations, floor finishes, heating, electrics and the level of internal refurbishment required around the new space.
A side return extension can be very effective where a narrow side passage is limiting the ground-floor layout. It can add width, improve daylight and help create a more usable kitchen, dining and family space, particularly in Victorian, Edwardian and terrace-style homes.
A wrap-around extension can create more transformative ground-floor space than a simple rear extension, but it is usually more complex and may carry more planning, party wall, drainage and structural considerations. The right option depends on your plot, budget, planning position and how much internal reconfiguration is needed.
Yes. Kitchen extensions are a core part of our work. We can coordinate layout, services, lighting, structural openings, glazing, finishes and installation so the new space functions properly as a family kitchen, dining and living area.
Yes. A garage conversion can be combined with a house extension, internal refurbishment or reconfigured ground-floor layout where it improves the overall use of space. We review structure, insulation, fire safety, access, drainage and Building Regulations before recommending the best route.
Yes. We aim to provide fixed-price clarity once the scope, drawings, specification and site conditions are understood. This helps you compare the real project cost rather than relying on vague square-metre estimates.
Yes. We complete snagging and provide aftercare support to protect the finish and performance of your completed house extension.
Some house extensions can be built under permitted development, but the allowed size depends on the property type, height, depth, boundary position, previous extensions and whether the home is in a restricted area such as a conservation area. We can review your Surrey or Elmbridge property and advise whether permitted development, a lawful development certificate or a planning application is the safest route.
Rear, side return, wrap-around, kitchen and double-storey extensions.
Ready to price your house extension?
Whether you are planning a larger kitchen, open-plan family space, extra bedrooms or a full ground-floor transformation, we can assess your property, explain the best extension route and provide fixed-price clarity before work begins.
House extensions across East Molesey, Elmbridge, Surrey and nearby South West London.