Over-Structure Extension Specialists
Looking to expand your home without giving up valuable garden or driveway space? An over-structure extension could be the perfect solution. At Happy Building, we are Surrey’s trusted specialists in designing and delivering these smart, space-maximising extensions. Whether it’s adding a stylish bedroom above a garage, creating a new home office over a kitchen, or building a complete second storey, our team transforms unused potential into functional, beautiful living areas.
With more than 600 completed projects across Surrey and South London, we have built a reputation for clarity, certainty, and craftsmanship. Homeowners choose us because we remove the guesswork from the process, combining practical design expertise with seamless construction and dependable project management. From the first sketch to the final snag list, every detail is managed by our in-house team, giving you confidence at every stage. With Happy Building, an over-structure extension is not just a build , it’s a stress-free journey to your dream home.
Why Choose an Over-Structure Extension?
Smarter Use of Space
An over-structure extension is one of the smartest ways to add both space and value to your property. Instead of building outward, we extend upward, creating additional bedrooms, home offices, or family living areas above your existing structure. This makes it an ideal solution when outdoor space is limited but more room indoors is essential.
Key Benefits
The advantages of an over-structure extension are clear. You can maximise space without sacrificing your garden or driveway, enjoy a cost-effective alternative to moving home, and add significant value to your property. These extensions are designed to integrate seamlessly with the existing character of your home, ensuring a natural and attractive finish.
Local Expertise You Can Trust
With our Surrey-based experience and a 99% planning approval success rate, you can be confident your project is in safe hands. We combine architectural creativity with practical buildability, ensuring your extension runs smoothly from start to finish, with no hidden surprises along the way.
Our Over-Structure Extension Services
Design & Planning
Every successful extension starts with smart, buildable design. Our architects work with you to create practical, cost-aligned plans that maximise available space without overshooting your budget. Unlike many studios that focus solely on drawings, we design with construction in mind. Every line on the page is structurally sound, budget-aware, and ready to pass planning quickly, setting the stage for a seamless build.
Planning Approval
We take the stress out of planning applications. With a 99% success rate across Surrey councils, our team knows how to navigate local policies and present designs that meet requirements the first time around. Because we maintain strong working relationships with local authorities, your application moves forward efficiently, avoiding delays that could set your project back by months.
Structural Engineering
An over-structure extension requires more than just vision, it requires strength and safety. Our in-house structural engineers carry out load-bearing assessments and advanced calculations to ensure your extension is future-proof. Whether building above a garage, kitchen, or single-storey addition, we guarantee your new structure is built to the highest standards of stability and durability.
Construction
Once planning is secured, our fully licensed and insured build team brings your extension to life. Every detail is executed with craftsmanship, care, and precision. We use vetted tradespeople and apply strict quality control at every stage of construction. To give you complete peace of mind, each project comes with a 6-year structural warranty, protecting your investment long after completion.
Project Management
Clear communication and accountability are at the heart of every project. That’s why you’ll have one dedicated senior project manager overseeing your extension from start to finish. You won’t be passed around or left in the dark ,instead, you’ll receive live updates, clear progress reports, and a single point of contact to guide you through every stage of the journey.
Aftercare
Our service doesn’t stop when we hand over the keys. We provide a 6-month rectification period to handle any small tweaks or adjustments that might arise once you’ve settled into your new space. With our responsive aftercare team on hand, you can enjoy your extension knowing we’re here to support you well beyond completion.
Whether you need design-only, build-only, or a full design and build package, Happy Building delivers over-structure extensions with clarity, care, and confidence. We remove the guesswork, manage the details, and provide the certainty Surrey homeowners deserve.
95%
of our clients say
they’d build with us again
"Happy Building guided us from planning to build with zero stress — and stayed exactly on budget. We’d do it again in a heartbeat."
150+
"Nothing but positive words to say about our experience with Happy Building so far. Geo took our brief and nailed it more or less straight away and we've been impressed with the service to date. Working with Geo on our project has made life a whole lot easier & something that initially seemed so daunting/stressful has so far been a delightfully calm experience. Can't wait to see what comes next."
6 in 10
“We chose Happy Building because they provide both the design and build process, and we had seen their local projects and were impressed. Happy Building has a straightforward process — we knew exactly what was happening and when. We knew what the cost would be and there were no surprises. They were proactive in their approach to any challenges that came up — they always came with a solution. Their team were accessible, engaged, and helpful at all stages. The build has transformed our house and changed the way we live in it — it’s better than we thought it would be!”
“We were very pleased with our experience working with Happy Building, especially Geo. He designed us a range of fantastic designs, including costing them up transparently and fairly. He was patient with our differing decisions, gave really sound advice, and communicated with us promptly and clearly. We wouldn't hesitate to recommend them!”
95%
of our clients say
they’d build with us again
"Happy Building guided us from planning to build with zero stress — and stayed exactly on budget. We’d do it again in a heartbeat."
The Happy Building Difference
Homeowners across Surrey choose Happy Building because we do things differently. Our approach combines expertise, transparency, and award-winning service:
- 99% Planning Success: We achieve one of the highest approval rates in Surrey thanks to our in-depth knowledge of local planning policies and strong relationships with councils.
- Guaranteed Budget Match
Every design is created to meet a target cost. What we plan is what we deliver, with no hidden charges or unexpected overspending. - 200+ Five-Star Reviews: More than 200 verified five-star reviews make us the most trusted design and build team in the region. Clients value our communication, build quality, and reliability.
- Award-Winning Projects: Recognised nationally for excellence, our projects have won ITV’s Big House, Little House and featured at Grand Designs Live. Our founder also serves on the board of the Federation of Master Builders.
- Local Experts: Based in Cheam Village, our Surrey studio is staffed by real architects, project managers, and builders who understand the local area, planning rules, and the needs of Surrey homeowners.
Over-Structure Extension Services Across Surrey and South London
At Happy Building, we proudly deliver over-structure extensions for homeowners across Surrey and South London. With a local studio in Cheam Village, our team understands the character of Surrey homes, the requirements of local councils, and the needs of families in the area.
Sutton
Extensions above garages and full second-storey builds. These projects help families stay in the area they love while enjoying the extra space they need.
Kingston-upon-Thames
Family home upgrades and rear extensions with upper-level additions. Our work here often focuses on balancing modern living with period property character.
Croydon
Modern over-structure designs for growing households. We create flexible layouts that adapt to the changing needs of busy families.
Epsom & Ewell
Cost-aligned extensions blending with traditional homes. Our designs respect the area’s architectural heritage while introducing fresh, practical spaces.
Banstead & Wallington
Additional bedrooms and loft-style conversions above existing structures. These solutions are perfect for families looking to expand without leaving their community.
Wimbledon & Surbiton
Contemporary extensions that maximise space in high-demand locations. Our expertise ensures designs meet planning expectations in these desirable areas.
Esher & surrounding Surrey towns
Luxury home upgrades and full property transformations. We deliver bespoke over-structure solutions tailored to the lifestyle of each client.
Recognised Industry Standards
At Happy Building, our reputation is built on more than promises — it is backed by respected accreditations and professional memberships. As proud members of the Federation of Master Builders, we meet the highest standards of quality and reliability in the industry. We are also TrustMark accredited, which means our work has been independently vetted for technical competence, customer service, and financial stability. To give you total confidence, every project comes with insurance-backed guarantees, so your investment is fully protected long after completion.
Awards, Media Features & Client Reviews
Our work has gained national recognition, having been featured on ITV’s Big House, Little House and showcased at Grand Designs Live, celebrating our award-winning design and build expertise. Most importantly, Surrey homeowners trust us because of our track record — with over 200 verified five-star reviews on Google, we are the highest-rated over-structure extension specialists in the region. When you choose Happy Building, you are choosing a team that combines professional credibility with real client satisfaction.
FREQUENTLY ASKED QUESTIONS
What exactly is an over-structure extension?
An over-structure extension is a building that adds a new living space above an existing section of your home, such as a garage, kitchen, or a single-storey area. It allows you to increase the internal space without reducing your outdoor area, making it ideal for properties with limited garden or driveway space.
Can any property support an over-structure extension?
Not every property is immediately suitable, but many can be adapted. Our structural engineers assess your existing foundations and load-bearing walls to determine whether strengthening work is needed before construction. This ensures that your new extension is safe, compliant, and long-lasting.
Do I need planning permission for an over-structure extension?
In most cases, yes you will need planning permission. Over-structure extensions typically exceed the limits of permitted development. However, our 99% planning approval rate means that we know exactly how to prepare and submit applications that align with Surrey council requirements, helping you to gain approval quickly and confidently.
How long does an over-structure extension take to complete?
Timelines vary depending on size, complexity, and planning approval, but most projects take between four and six months from the start of construction. Our team provides a clear schedule before work begins so that you know what to expect at every stage of the project.
Is an over-structure extension cheaper than moving home?
Yes, in most cases it’s significantly more cost-effective than relocating. You can gain valuable extra space without legal fees, stamp duty, or the disruption of moving. Many clients also find their property value increases once the extension is complete.
Can I live in my home during the build?
In many cases, yes. Our project managers plan construction phases carefully to minimise disruption, dust, and noise. For some larger builds, you may prefer to stay elsewhere temporarily, and we’ll always advise you honestly on the most practical solution.
What kind of rooms can be added above an existing structure?
You can add virtually any type of room, from a master bedroom with an en suite to a home office, guest suite, or family playroom. We’ll work with you to design a layout that complements your existing home and lifestyle needs.
How do I know if my garage can handle an upper storey?
Our engineers carry out a full structural assessment to check your garage’s foundations, walls, and materials. If reinforcement is required, we’ll plan and cost that work upfront to ensure your new space is completely safe and structurally sound.
What’s included in Happy Building’s over-structure extension service?
We offer a complete design and build service covering architecture, planning, structural engineering, construction, and aftercare. From your first consultation to the final sign-off, everything is handled in-house for a seamless, stress-free experience.
How much does an over-structure extension cost?
Costs vary depending on the size, design, materials, and structural requirements, but we always provide transparent quotes before starting. Our design team aligns every plan to your target budget, ensuring that what we design is achievable and cost-efficient.
Start your project today
Our complimentary consultation is the first step toward creating the extra space your family needs , whether it’s a new bedroom, office, or an entire second floor. You’ll receive expert guidance on design options, planning requirements, and clear costings with no obligation to proceed.
Contact us today or email office@happybuilding.co.uk
