Single Storey Extension Experts
At Happy Building, we’ve completed hundreds of single storey extensions across South London and Surrey, from sleek, modern kitchen-diners to character-filled garden rooms. Every project is approached with the same promise: no stress, no delays, no budget shocks.
Our integrated design-and-build team works under one roof, meaning your architects, project managers, and site teams collaborate daily to keep your extension buildable, beautiful, and on time. We don’t just hand you a set of plans and wish you luck, we’re there from the first sketch to the final snag list, ensuring every detail is exactly as promised.
Our Proven Design & Build Process
We’ve honed our process to remove uncertainty and keep your build moving smoothly from day one.
STEP 1
Planning With Certainty
With a 99% planning approval rate, we know what each local council expects — from Sutton to Kingston and beyond. Our planning team handles all drawings, submissions, and negotiations, ensuring your application is complete, compliant, and fast-tracked wherever possible.
STEP 2
Cost-Aligned Design
We start every project with your budget in mind, not as an afterthought. Our Market Rate Check tool benchmarks your extension design against real construction costs in the area, so there are no unwelcome surprises once you break ground.
STEP 3
Quality Construction
Our fully licensed and insured build team works to strict quality standards, with a dedicated site manager overseeing progress every day. Every single storey extension we deliver comes with a 6-year structural warranty and after-care support, so you can enjoy your new space with complete peace of mind.
STEP 4
Single Point of Contact
One project lead will be your voice and your advocate throughout the process. They’ll coordinate architects, estimators, and site managers, keeping communication clear and ensuring your design vision is protected right through to completion.
Single Storey Extensions We Specialise In
We design and build single storey extensions that work beautifully with your home’s architecture and your lifestyle. Every project is tailored to your space, budget, and vision — here are some of our most popular options:
Rear Kitchen Extensions
A rear extension can completely transform the feel of your home, creating a spacious kitchen-diner that flows into a living area. Ideal for families, it gives you room to cook, eat, and relax together, with options for skylights, bi-fold doors, and underfloor heating to add comfort and style.
Side Return Extensions
In many Victorian and Edwardian homes, a narrow side alley sits unused. By extending into this space, we can widen your kitchen or dining area without encroaching too far into the garden, maximising every inch of your property footprint.
Wrap-Around Extensions
For the ultimate in open-plan living, a wrap-around extension merges a rear and side return extension into one continuous space. This layout is perfect if you want a large family hub with multiple zones for cooking, dining, and lounging — all flooded with natural light.
Garden-Facing Glass Extensions
If you love light-filled spaces, a garden-facing glass extension is the answer. Floor-to-ceiling glazing, sliding or bi-fold doors, and minimalist framing create a seamless link between your home and garden, ideal for entertaining or simply enjoying the view year-round.
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."
Why Choose a Single Storey Extension?
A single storey extension is one of the most cost-effective ways to transform your home without the upheaval of moving. It can:
- Create a larger kitchen-diner or open-plan living space — the heart of modern family life, with room for entertaining, cooking, and relaxing together.
- Add a home office, playroom, or guest suite — flexible spaces that adapt as your needs change.
- Improve flow and connection to the garden — think wide bi-fold doors, level thresholds, and outdoor entertaining areas that feel like an extension of your interior.
- Increase property value and appeal — extensions often return more than their cost in added value, especially in high-demand areas of Surrey and South London.
The Happy Building Difference
Choosing the right partner for your single storey extension can make the difference between a smooth, enjoyable project and a stressful one. Here’s why homeowners across South London and Surrey choose Happy Building:
Local Expertise
We’re not a faceless online service — we have a real studio in Cheam Village, where our architects, project managers, and estimators work together under one roof. You’ll meet with real people who understand local planning rules, council processes, and Surrey’s property styles.
Guaranteed Budget Match
What we design is what we deliver, and for the price we agreed. By aligning design and build under one team, we remove the all-too-common “overdesign” that leads to spiralling costs.
200+ 5-Star Reviews
Homeowners consistently rate us five stars for quality, communication, and peace of mind — more than any local competitor. Our track record speaks for itself.
Award-Winning Builds
From ITV’s Big House, Little House to four consecutive years as a featured expert at Grand Designs Live, our projects have been recognised for their quality, creativity, and craftsmanship.
Ready to Start Your Single Storey Extension?
Book your free consultation today and take the first step towards transforming your home. We’ll visit your property, discuss your ideas, explain planning and cost options, and outline a realistic timeline so you can move forward with confidence.
