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Plan a house extension hampshire: Costs, Permits & Builders
- Dan Hall
- 4 days ago
- 16 min read
Thinking about extending your home in Hampshire? It's often a smart move. Not only does it give you the extra living space you desperately need, but it can also be a sound financial investment that boosts your property's value—often proving far more sensible than the hassle and cost of moving.
Our in-house service's team handles the whole process, from the first rough sketches right through to the final build, working with homeowners across the county. This guide is here to walk you through it all, step by step, to help turn your ideas into a reality.
Why Extend Your Home in Hampshire
It’s the classic dilemma for homeowners across Hampshire: move or improve? When you start adding up the costs of moving—stamp duty, legal fees, removal vans—extending your current home often comes out on top as the more financially savvy choice. This is especially true in sought-after areas like Southampton, Highcliffe, and Christchurch, where the property market is consistently strong.
With house prices on the rise, staying put and making the most of what you have is an attractive option. For example, recent figures showed the average house price in East Hampshire hitting £455,000. Semi-detached homes, which are perfect candidates for extensions, saw a healthy 5.1% price increase year-on-year, averaging £445,000. These numbers really highlight why so many people are choosing to invest in their existing assets instead of diving into a competitive buying market.
Adapting to Modern Lifestyles
It's not just about the money, though. The way we live has fundamentally changed. The boom in remote working means a proper home office is no longer a luxury, and growing families need more flexible spaces to live and breathe. A well-designed house extension in Hampshire is the perfect answer.
Our in-house service's job is to help you transform your home to meet these new needs, whether that means adding:
A big, open-plan kitchen-diner where everyone can gather.
A quiet, light-filled home office tucked away from the daily chaos.
An extra bedroom or even a self-contained annexe for multi-generational living.
A practical utility room to keep the clutter out of sight.
A thoughtfully planned extension does more than just add square footage. It completely reimagines your home's layout to improve its flow, functionality, and how you feel living in it every day. Our in-house service's team works with you from the initial concept to the final handover to make sure the new space fits seamlessly with your existing home.
A Seamless Process from Start to Finish
Kicking off a building project can feel like a huge undertaking, but it really doesn't have to be. When you opt for our all-in-one design and build service, you have a single point of contact who is responsible for every single stage. It simplifies everything.
Our team of experts, from architects to our own Gas Safe engineers, handles it all under one roof. We're well-versed in navigating local council requirements from Bournemouth to Poole and Ringwood, ensuring a smooth journey from getting planning permission to applying the final coat of paint. For more ideas on how to get the best return, check out our guide on budget-friendly, high-impact projects. This comprehensive approach saves you time, cuts down on stress, and gives you complete clarity on your investment from day one.
Understanding Your Hampshire Extension Costs
Let's get straight to it. One of the first questions on any homeowner's mind is, "How much will my house extension in Hampshire actually cost?" Getting beyond vague estimates is vital for planning a project you can afford and enjoy, without sleepless nights. Understanding the real figures from the get-go helps you set a realistic budget and make informed decisions.
The final price tag isn't just one number; it's a sum of many parts. Everything from the size and complexity of your design to the specific materials and finishes you fall in love with will play a role. A small, simple single-storey extension in Poole will have a completely different cost profile to a large, architect-designed two-storey wraparound in Highcliffe. That’s why a detailed, transparent quote from our in-house service's team is non-negotiable.
Breaking Down the Main Cost Factors
When we put together a quote, our in-house service's team looks at every single detail. We do this to avoid any unwelcome surprises popping up later on. We don't just hand you a number; we walk you through what’s behind it.
Here are the key variables that will shape your budget:
Size and Type of Extension: A single-storey build is usually the most cost-effective per square metre. A double-storey or wraparound design, on the other hand, requires far more structural work, materials, and labour.
Structural Complexity: Is your heart set on an open-plan layout that needs huge steel beams? Are you planning to move load-bearing walls or design a complex roof? These elements require careful engineering and highly skilled tradespeople, which naturally affects the cost.
Site Conditions: The ground your house sits on is a huge factor. Poor soil conditions, which we sometimes find around Southampton or Bournemouth, might mean digging deeper, more expensive foundations. Access is another one; a terraced house with no rear access presents more logistical hurdles than a detached property with a big garden.
Choice of Materials: The price range for materials is vast. From bricks and roof tiles to windows and flooring, your choices matter. High-end bifold doors, for instance, will cost significantly more than standard uPVC French doors.
A word of warning: the cheapest quote is rarely the best. If an estimate seems too good to be true, it almost certainly is. It probably omits key costs like VAT, skip hire, or making good the mess in the existing parts of the house. Our all-in-one service provides a fixed-price quote covering the entire project, from architectural drawings to the final lick of paint.
What You Can Expect to Pay in Our Region
While every project is unique, having some ballpark figures helps. Across the UK, the average house extension project costs around £40,000. More specifically, you're looking at £1,700 to £1,900 per square metre for single-storey builds and £1,500 to £1,800 per square metre for double-storey projects.
To put that into perspective, here’s a quick breakdown of what you might expect to pay in Hampshire for some common extension types.
Estimated Costs for Different House Extensions in Hampshire
Extension Type | Average Cost per m² | Typical Size (m²) | Estimated Total Cost |
|---|---|---|---|
Single-Storey Rear Extension | £1,700 – £1,900 | 25 | £42,500 – £47,500 |
Single-Storey Side Return | £1,800 – £2,000 | 15 | £27,000 – £30,000 |
Two-Storey Rear Extension | £1,500 – £1,800 | 50 | £75,000 – £90,000 |
Wraparound Extension | £1,900 – £2,200 | 40 | £76,000 – £88,000 |
Disclaimer: These figures are estimates for guidance only. Your final cost will depend on your specific design, materials, and site conditions.
The good news? Hampshire has a great track record for project viability. Designers in our area report a fantastic 97% planning approval success rate. For a deeper dive into the numbers, you can explore more detailed house extension costings in our practical guide.
Why a Professional On-Site Quote is Essential
An online cost calculator can give you a rough idea, but it can’t see the unique quirks of your home. Nothing beats a professional site visit for getting an accurate, reliable figure you can actually bank on.
When our in-house service's team visits your property, we’re not just there for a quick look. We assess:
The condition of the existing structure.
Ground conditions and drainage.
Access for machinery and material deliveries.
Connections to utilities like water, gas, and electricity.
This thorough, boots-on-the-ground approach is how we provide a comprehensive quote that you can trust. Our service ensures every aspect, including safety checks from our in-house Gas Safe registered engineers, is factored in from day one. This level of detail gives you complete peace of mind and lets you budget with confidence for your dream house extension in Hampshire.
Navigating Planning Permission in Hampshire
Getting the green light for your house extension in Hampshire is a huge milestone. But let’s be honest, the world of planning regulations can feel like a maze of local council rules and endless paperwork. Every authority, from Southampton to Bournemouth, has its own little quirks. This is where using our in-house service's team who knows the local landscape really pays off.
The good news? Not every extension needs a full-blown planning application. A lot of projects actually fall under what’s called Permitted Development (PD) rights. This is a great route that lets you build certain extensions without formal permission, as long as you stick to some very strict size and design limits. Get it wrong, though, and you could be facing a costly mistake.
Our in-house service's team handles all of this for you. With a 97% approval success rate, we’ve got a knack for figuring out the quickest, most straightforward path for your project. We'll manage all the paperwork and chats with the local councils, whether you're in Highcliffe, Christchurch, or Ringwood, saving you a massive headache.
Permitted Development vs Full Planning Application
First things first, we need to figure out which path your project needs to follow. It all comes down to the size, scale, and design of what you have in mind.
Permitted Development is perfect for more straightforward jobs. If you have a detached house, you can generally extend up to eight metres to the rear with a single-storey addition. For semi-detached or terraced homes, that's trimmed back to six metres. But there's a list of conditions you have to meet:
Your extension can't take up more than half the land around the original house.
The materials you use have to look similar to your existing property.
It can’t be higher than the existing roof.
A Full Planning Application is the route for bigger, more ambitious designs that step outside those PD limits. This usually includes two-storey extensions, any project in a Conservation Area or an Area of Outstanding Natural Beauty, or plans that might affect your neighbour’s light. It’s a much more detailed process where the council really scrutinises the design's impact on the local area.
We’ve designed our service to take this whole burden off your shoulders. We’ll check your plans against the latest regulations for your specific patch, from Poole to the New Forest, then prepare and submit the right application for you, making sure every single detail is spot on.
Understanding Building Regulations
Once you’ve got planning sorted, the next hurdle is Building Regulations approval. This isn't optional—it's a separate legal requirement to make sure your new extension is safe, structurally sound, and energy-efficient. It’s less about what the extension looks like and much more about how it’s built.
Building Regs cover a whole host of things, including:
Structural Integrity: Making sure the foundations are right and the walls can take the load.
Fire Safety: Things like proper escape routes and using fire-resistant materials.
Energy Efficiency: This covers insulation, ventilation, and even your boiler's performance.
Drainage and Electrics: All work must meet safety standards. Any electrical work has to be signed off by a qualified professional, and gas work must be done by a Gas Safe registered engineer—like the ones on our team.
Our experts manage this entire process, liaising with local authority building control inspectors to ensure every stage of the build is checked and signed off correctly. If you want to dig deeper into why professional oversight is so crucial, this article on navigating regulations and permits is a useful read.
The Party Wall Act Explained
If you live in a terraced or semi-detached house, the Party Wall etc. Act 1996 is almost certainly something you’ll need to think about. This law is there to prevent and resolve disputes between neighbours when your building work involves a shared wall or boundary.
You must give your neighbours a formal 'Party Wall Notice' if your extension plans involve:
Building on or right up to the boundary line between your properties.
Cutting into a shared party wall.
Digging foundations within three metres of a neighbour's home.
Getting this process right is crucial to avoid legal wrangles and project delays. As part of our in-house service's, we can guide you through this or put you in touch with a specialist Party Wall Surveyor to make sure all your legal obligations are handled smoothly and professionally. Want to learn more? Our detailed guide explains UK home extension planning permission in even more detail.
Choosing the Right Hampshire Build Partner
The single most important decision you'll make for your house extension in Hampshire is choosing who will actually build it. Get this right, and the whole process can be an exciting, collaborative journey. Get it wrong, and you could be facing budget nightmares, endless delays, and a whole lot of stress. Your project's success genuinely hangs on the team you bring on board.
This is where you have a fundamental choice to make about how you structure your project. The traditional route involves hiring an architect or designer first, getting your plans drawn up, and then putting those plans out to tender with several different builders. It can work, but it often creates a disconnect—the architect's grand vision might not line up with a builder's practical or financial realities. When problems pop up, it can quickly turn into a frustrating game of finger-pointing.
The Advantage of a Single Design and Build Service
There’s another way, and it's one that’s becoming more popular for good reason: the all-in-one design and build model. When you work with our in-house service, you get one dedicated team and one point of contact for everything. From the first sketches in Christchurch to the final plumbing sign-off in Highcliffe, it’s all handled under one roof.
The benefits here are huge. Communication is seamless because the designers, project managers, and builders are colleagues, not strangers. They're all on the same page from day one, which pretty much eliminates the "blame game." Accountability is crystal clear, timelines are tighter, and your budget is far more secure because the people who will actually build the extension are involved in the design phase, making sure the plans are realistic from the get-go.
Our approach means you have one cohesive team managing every detail. From our architectural designers to our Gas Safe registered engineers, everyone in our in-house service's team is working towards the same goal, ensuring a smoother and more efficient project for your Hampshire home.
A design and build service offers a more streamlined approach, but many homeowners still prefer the traditional method of hiring an architect and contractor separately. To help you decide, here’s a quick comparison of the two.
Comparing Build Approaches Design-Build vs Traditional
Feature | Our In-House Design & Build Service | Traditional Method (Separate Hires) |
|---|---|---|
Accountability | Single point of responsibility for the entire project. | Divided between architect and builder; potential for disputes. |
Communication | Streamlined and integrated within one team. | Can be fragmented, requiring you to coordinate between parties. |
Budget Control | Costs are managed from the design phase, reducing surprises. | Designs may exceed budget, requiring costly revisions later. |
Timeline | Overlapping design and build phases can speed up the project. | Sequential process can lead to longer overall timelines. |
Ultimately, the best path depends on how hands-on you want to be and your comfort level with managing multiple contracts and relationships.
Vetting Your Potential Hampshire Builder
No matter which route you take, doing your homework is non-negotiable. You need a partner with proven experience, proper credentials, and a history of happy clients right here in the Hampshire region.
Before you even think about signing a contract, make sure you're asking the tough questions:
Can you show me a portfolio of similar projects you’ve completed in areas like Bournemouth, Southampton, or Poole? You need to see that they have relevant local experience and that their finished work is up to your standard.
Are you and your subcontractors fully insured? Always ask to see their Public Liability and Employers' Liability insurance certificates. This is your safety net if an accident happens on your property.
Will I receive a detailed, itemised quote and a formal contract? A vague, one-page quote is a massive red flag. A professional will provide a complete breakdown of costs and a proper contract that covers the scope of work, payment schedule, and timeline.
Who will be my main point of contact and how often will we get updates? Consistent, clear communication is everything. You need to know who is running the show day-to-day.
To help you dig deeper, we've put together a detailed resource on finding trusted builders in Hampshire which covers this crucial process in more detail.
Red Flags to Watch Out For
Knowing what to avoid is just as important as knowing what to look for. Steer clear of any builder who:
Offers a "cash" deal or asks for a huge upfront deposit. This often points to financial trouble or an attempt to operate off the books.
Is hesitant to provide references or show you past projects. Any builder proud of their work will be excited to show it off and let you speak to former clients.
Uses high-pressure sales tactics. This is your home and a major investment. You should never feel rushed into signing anything.
A great build partner isn't just a contractor—they're a collaborator. They'll respect your vision, communicate openly, and have the skill to bring your house extension in Hampshire to life with genuine care and professionalism.
Your Project Timeline from Start to Finish
With the designs signed off and all the necessary permissions granted, the real fun of your house extension in Hampshire can begin. It helps to have a clear idea of the construction sequence so you know what to expect, from the first spade in the ground to the day we hand over the keys. While no two projects are identical, a typical build follows a pretty logical path.
Managing this process is all about minimising the disruption to your life. Because our in-house service's team oversees every last detail, we can make sure the project runs like clockwork, stays on schedule, and you’re kept in the loop every step of the way. A well-managed project is a stress-free one.
From Foundations to First Fix
The early stages are all about creating a solid, weatherproof shell. This is where you’ll see the most dramatic progress as the bones of your new space start to emerge.
It all kicks off with breaking ground. Our team will meticulously mark out the extension's footprint and begin digging out the foundations—a critical step that supports the entire new structure. Once the trenches are dug and get the nod from building control, we pour the concrete and build up the blockwork to floor level.
Then, the main structure goes up, with walls built to roof height. Once the frame is complete, the roof trusses are lifted into place, followed by tiling and weatherproofing. With the roof on and the windows and external doors fitted, your extension is officially a secure, watertight shell, ready for the internal work to get underway.
Second Fix and Finishing Touches
With the heavy lifting done, our focus shifts to the interior. This is where we install all the systems that turn a building into a proper home, a phase we call the "first and second fix" stage.
Here's what that generally looks like:
First Fix Electrics and Plumbing: Before any plasterboard goes up, our qualified electricians and in-house Gas Safe engineers will run all the necessary wiring and pipework through the walls and floors.
Plastering: Next, the internal walls and ceilings are plasterboarded and skimmed to create a smooth, clean finish that’s ready for decorating.
Second Fix Joinery and Systems: This is when it really starts to feel like a room. Doors are hung, skirting boards are fitted, and our electricians come back to install sockets, switches, and light fittings. At the same time, our plumbing team will connect up radiators, taps, and any bathroom fittings.
Before any of this happens, though, you have to choose the right partner to guide you through it all.
This simple three-step process—doing your homework, getting detailed quotes, and signing a clear contract—is the foundation of a successful project before a single shovel hits the ground.
The Decoration and Handover Phase
The final stage is where your vision truly comes to life. Once the structural work on your Hampshire extension is complete, the exciting part begins. You'll want to review a practical resource like this helpful guide on choosing paint colors for rooms to help with those important decisions.
At this point, our decorators get to work preparing and painting the walls and woodwork. After that, the final flooring is laid, and kitchen units or bathroom suites are installed. We then carry out a thorough snagging process, checking every single detail to make sure our work is finished to the highest standard.
It’s clear that the demand for high-quality living space is booming. With 22.6 million British workers now working from home at least some of the time, there’s a real need for larger homes with dedicated offices and gardens. This trend has made home extensions an incredibly popular choice for families in thriving areas from Christchurch to Ringwood.
A Client's Experience in Ringwood:"We were nervous about the disruption, but the team managed the timeline brilliantly. They kept the site so tidy and gave us daily updates, so we always knew what was happening next. Seeing the foundations go in and then the roof go on was incredibly exciting. The final handover was seamless, and we were enjoying our new kitchen diner within the timeframe they promised."
Finally, after a deep clean, we proudly hand the keys back to you. We'll walk you through your new space, show you how everything works, and provide all the completion certificates from building control and our Gas Safe engineers. It’s the final step that gives you complete peace of mind so you can start enjoying your beautiful new house extension in Hampshire straight away.
Common Questions About Hampshire Extensions
Taking the plunge on a house extension is a huge decision, and it’s only natural to have a list of questions running through your head. To give you a bit more confidence as you start planning, we've gathered some of the most common queries we hear from homeowners across Hampshire, from Bournemouth right through to Southampton.
How Long Does a Typical House Extension Take in Hampshire?
Every project has its own unique rhythm, but a typical single-storey extension in Hampshire usually takes somewhere between 10 to 18 weeks to build, from the moment we break ground to the day we hand you the keys.
Of course, this timeline can shift. The complexity of the design, challenges on-site like tricky ground conditions, or even the classic unpredictability of the British weather can all have an impact. Our in-house service's project managers map out a detailed schedule from the get-go and keep you in the loop with regular updates, making the whole process feel smooth and predictable, whether your home is in Highcliffe or Poole.
Do I Always Need Planning Permission in Southampton or Christchurch?
Not necessarily. A lot of smaller, more straightforward extensions can be built under what are known as 'Permitted Development' rights. This means you might be able to skip a full planning application altogether. The catch is, the rules are very specific and can get complicated fast.
Whether you need permission often comes down to:
The overall size and height of your planned extension.
Where your property is located (for instance, if you're in a Conservation Area).
How close you intend to build to your property's boundary lines.
Our in-house service's team will carry out a professional assessment of your plans to figure out the right path forward. From there, we handle all the paperwork and chats with the local council for you, taking the headache out of the process.
By managing the application for you, we can use our experience dealing with councils across Hampshire and Dorset. We know what they look for, which helps us get every detail right, avoid needless delays, and get your project the green light.
What Is the Biggest Hidden Cost I Should Prepare For?
Unexpected costs are the number one fear for anyone extending their home, and they usually pop up from issues that were impossible to see before work started. It could be anything from digging up old, forgotten drains under the garden to discovering problems with the existing electrics once we open up a wall.
This is where our comprehensive design and build service really shines. We conduct thorough initial surveys to spot potential issues early and provide a fixed-price quote covering all the agreed work. This gives you financial clarity from day one and helps keep your house extension hampshire project firmly on budget.
Can I Live in My House During the Extension Work?
Yes, in most cases, you can absolutely stay in your home while we build. Our teams have years of experience working in occupied properties and are experts at keeping disruption to a minimum.
We’ll carefully section off the work area to control dust and noise, and we always leave the site safe and tidy at the end of each day. We'll also walk you through the project plan beforehand, so you know about any brief periods where services like water or power might need to be switched off for connections.
For a deeper dive into the rules that ensure your extension is safe and built to last, our guide explains UK Building Regulations for extensions in plain English.
Ready to turn your vision into a reality? The team at Hallmoore developments provides a complete in-house service to manage your entire project, from initial design to final build. Contact us today for a no-obligation chat about your Hampshire home extension.
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