Local house extension builders
House extensions, loft conversions and design & build in East Molesey, Elmbridge and Surrey
HWP Design & Build helps homeowners across East Molesey, Elmbridge, Surrey and nearby South West London create more space with carefully planned house extensions, loft conversions, kitchen extensions, garage conversions, refurbishments and full residential design and build services.
From our East Molesey base, we work with semi-detached, detached, Victorian, Edwardian, 1930s and post-war homes, helping clients plan around access, neighbouring properties, roof structure, drainage, Building Regulations, party wall matters and local planning considerations.
Explore our house extensions in Surrey, loft conversions in Surrey, kitchen extensions and East Molesey design and build services.
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Welcome to HWP Design & Build
Residential design & build specialists with one clear route from survey to handover.
HWP Design & Build is the trading name of SMA Design & Build Ltd, providing managed home improvement projects for homeowners across East Molesey, Elmbridge, Surrey and South West London.
With more than 30 years of hands-on experience, we coordinate design, structural input, approvals, construction, finishing and aftercare for extensions, loft conversions, renovations, basement fitout and re-roofing projects.
Our approach is built around clear specifications, fixed-price quotation clarity, practical design advice and one accountable team, reducing the confusion that often comes from managing separate trades.
What we do
What does HWP Design & Build do?
HWP Design & Build plans and delivers residential house extensions, loft conversions, refurbishments and design & build projects across East Molesey, Elmbridge, Surrey and nearby South West London. We help homeowners assess feasibility, understand planning and Building Regulations, agree a clear specification, and move into construction with one accountable team.
House extensions
Create larger kitchens, open-plan living areas, utility spaces, offices and extra bedrooms with rear, side return, wrap-around, single-storey or double-storey extensions.
Explore house extensionsLoft conversions
Convert unused roof space into a bedroom, office, bathroom or master suite with practical advice on roof type, stairs, structure, fire safety and natural light.
Explore loft conversionsBasement fitout & finishing
Transform unused below-ground space into a practical room with basement fitout, finishing, lighting, ventilation, moisture-conscious detailing and coordinated project management.
Explore basement fitoutRenovations & refurbishments
Improve older or impractical layouts with structural openings, internal reconfiguration, new finishes, better insulation, upgraded services and coordinated project management.
Explore renovations
Our services
Explore our full range of design & build services
Browse the main services and specialist project types we provide, from house extensions and loft conversions to planning support, Building Regulations coordination and project management.
One accountable team for design, approvals, build and finishing.
Planning a home extension, loft conversion or refurbishment?
Tell us what you want to achieve and we’ll help you understand the right construction route, likely design considerations, planning or Building Regulations requirements and the fixed-price scope needed to move your project forward with confidence.
Serving East Molesey, Elmbridge, Surrey, South West London and surrounding areas.
Why choose HWP Design & Build?
Fixed-price clarity, one-team accountability and trusted local experience
Choosing a builder is about trust, communication and certainty. Our process is designed to reduce surprises before construction begins, keep responsibility clear and give homeowners a smoother route from early ideas to finished build.
Fixed-price quotation clarity
We build quotations around an agreed scope and specification, helping you understand what is included before work starts.
One accountable team
Design, structure, approvals, build, finishing and aftercare are coordinated through one managed route, reducing confusion and handover gaps.
30+ years’ experience
Our team brings decades of hands-on experience across domestic construction, house extensions, loft conversions and refurbishments.
Local Elmbridge knowledge
Based in East Molesey, we understand the property types, planning sensitivities, access constraints and homeowner priorities common across Elmbridge and Surrey.
Planning and compliance support
We help you understand planning permission, permitted development, structural requirements, Building Regulations, Building Control and party wall considerations.
Aftercare and guarantees
We support the project beyond completion with snagging, aftercare and clear information about workmanship, protection and guarantees.
Project Team
The people and skills behind your design & build project
Every successful extension or loft conversion needs the right mix of design thinking, structural input, site management and communication.
Architectural Designer
Develops layouts, visuals and planning-ready drawings to improve space, light and flow.
Structural Engineer
Coordinates beams, openings and structural details for safe, compliant construction.
Project Manager
Manages programme, budget, communication, site coordination and quality control.
Site Manager
Oversees day-to-day works, health and safety, tidy working practices and finish quality.30+
Years Design
& Build Experience
10
Years Structural
Guarantee
5%
Scheduling Discount
With Fixed Fee Quotation
500+
Successful Projects
Delivered
Areas We Cover
Local design & build services across Elmbridge, Surrey and South West London
We are based around East Molesey and work with homeowners across nearby Surrey and South West London locations, with a strong focus on local property types, planning considerations and practical site constraints.
From start to finish, our experience with HWP Design & Build was amazing. The builders were professional and courteous, making the whole process smooth and stress-free.
Loft Conversion
Olivia Emily, London
I recently had HWP Design & Build complete our loft conversion and I couldn’t be happier with the results. From start to finish they were professional, lovely to chat with and truly invested in making sure everything was done to the highest standard.
Loft Conversion
William Knight, London
We can't thank Sophia enough for her incredible support after we were left with multiple issues by our previous builders. She was highly responsive, professional, and guided us toward the best solutions while considering our budget constraints.
Extension & Loft
Danni O’Mahoney, London
Fabulous experience. Always wary when starting a big project, but HWP Design & Build made it seamless. Our extension is exactly how we’d hoped, and the team couldn’t do more for us.
Extension
Jessica Hawkins, London
Wonderful customer service. Went above and beyond to answer our questions and kept us updated. Attention to detail was brilliant and they worked with us to make sure it was everything we wanted.
Extension
Chloe May, London
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Latest Insights
Planning advice for extensions, loft conversions and home improvements
Explore practical guides on costs, planning permission, permitted development, Building Regulations, loft conversion types and sustainable upgrades for Surrey and Elmbridge homes.
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East Molesey property improvement guide
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Garage Conversion vs Rear Extension
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Party Wall Notice for Rear or Side Return Extensions
In many cases, yes. But not every rear extension or side return extension needs a party wall…
Read MoreFrequently asked questions about HWP Design & Build
HWP Design & Build specialises in residential house extensions, loft conversions, renovations and refurbishments, basement fitout and finishing, planning support, Building Regulations coordination and full project management across East Molesey, Elmbridge, Surrey and nearby South West London.
HWP Design & Build is a trading name of SMA Design & Build Ltd. The public-facing brand is HWP Design & Build, while SMA Design & Build Ltd is the registered legal entity.
Yes. HWP Design & Build provides house extension design and build services across Surrey, Elmbridge and nearby South West London, including East Molesey, West Molesey, Esher, Thames Ditton, Walton-on-Thames, Weybridge, Surbiton and Kingston upon Thames. See our house extensions service.
Yes. We are based in East Molesey and work across the wider Elmbridge area, helping homeowners plan and build rear extensions, side return extensions, wrap-around extensions, kitchen extensions, single-storey extensions and double-storey extensions. Start with our East Molesey and Elmbridge pages.
We build a range of home extensions, including rear extensions, side return extensions, wrap-around extensions, single-storey extensions, double-storey extensions, kitchen extensions and garage conversions.
Yes. We design and build kitchen extensions across Surrey and South West London, helping homeowners create brighter kitchen-diners, open-plan family rooms, utility spaces and better connections to the garden. See our kitchen extensions service.
Yes. We plan and build loft conversions across Surrey and South West London, including dormer loft conversions, hip-to-gable loft conversions, mansard loft conversions and Velux rooflight loft conversions.
Yes. We can assess your layout, roof space, garden depth, budget, planning constraints and family needs to help you decide whether a loft conversion, rear extension, side return extension, wrap-around extension, garage conversion or internal refurbishment is the best route.
The cost of a house extension in Surrey depends on the size, structure, specification, glazing, kitchen or bathroom requirements, drainage, access and whether planning or party wall matters are involved. We provide fixed-price quotation clarity once the scope and specification are agreed. You can also read our Surrey house extension cost guide.
Loft conversion costs vary depending on roof type, head height, structural requirements, staircase position, bathroom installation, fire safety upgrades, insulation and finish level. Dormer, hip-to-gable, mansard and Velux rooflight conversions can all differ in complexity. See our Elmbridge loft conversion cost and planning guide.
Yes. We can manage your project from early advice and measured survey through to design coordination, structural input, planning, Building Regulations, construction, finishing and aftercare. See our Design & Build service and our process.
Yes. Some extensions and loft conversions may fall under permitted development, while others need a planning application. We advise early and can coordinate planning-ready drawings and submissions where required. See our Planning Permission support.
Most structural home improvement projects need Building Regulations approval. We coordinate the relevant design, structure, insulation, fire safety, drainage and inspection requirements with Building Control. See Building Regulations.
Yes. Many extensions and loft conversions near neighbouring properties need early party wall consideration, especially where work affects shared walls, boundaries, excavations or neighbouring structures. We provide practical guidance before work begins. See Party Wall Support.
We aim to provide clear, fixed-price quotations based on an agreed scope and specification. This helps you understand what is included, budget with greater confidence and reduce uncertainty before work starts.
Our positioning is built around one accountable team and one clear route of communication. Where specialist input is required, it is coordinated as part of the wider project rather than leaving homeowners to manage separate trades.
Yes. We take compliance, insurance, workmanship and aftercare seriously. You can read more on our Accreditations, Insurance & Guarantees page.
Often, yes. It depends on the scale and phase of the works. We plan access, protection, sequencing, site safety and communication to reduce disruption, and we will advise honestly if temporary decanting is safer or more practical.
Timescales vary depending on design, approvals, structure, specification and site access. We outline a realistic programme before work starts and keep you updated throughout. For a typical route, see our process.
We cover East Molesey, West Molesey, Elmbridge, Hampton Court, Thames Ditton, Long Ditton, Esher, Walton-on-Thames, Weybridge, Kingston upon Thames, Surbiton, Claygate, Cobham, Teddington, Twickenham, Richmond, Wimbledon, Raynes Park, Putney, Wandsworth, Battersea and nearby Surrey and South West London locations. See all areas we cover.
Yes. View our recent projects, including extensions and loft conversions in East Molesey, Esher, Surbiton, Walton-on-Thames and Wimbledon.
Send us a short outline of your project and we will arrange a site visit to review the scope, constraints and next steps. Start here: request a quote.