Single Storey vs Double Storey Extensions | Maidstone Builder Guide
When your Maidstone home needs more space, an extension is often the smartest solution. Rather than facing the expense and disruption of moving, you can add exactly the rooms you need while staying in the location you love. But one of the first decisions you’ll face is whether to build single storey or double storey.
Both options have clear advantages depending on your property, your budget, and what you’re trying to achieve. This guide compares the two approaches, helping Maidstone homeowners make an informed choice before committing to a project.
Understanding the Basics
A single storey extension adds ground floor space only, typically extending outward from your existing kitchen, dining room, or living area. Most single storey extensions in Maidstone create open-plan kitchen-diners, larger living rooms, or dedicated home offices.
A double storey extension builds two floors simultaneously, adding ground floor space with additional rooms above—usually bedrooms or bathrooms. You’re essentially stacking one extension on top of another, sharing foundations, walls, and roof structure between both floors.
The choice between them depends on several factors: what space you actually need, your budget, your property type, planning constraints, and how the extension will affect your home’s proportions and your neighbours.
Cost Comparison
Budget often drives the decision, so let’s address costs directly.
A single storey extension in Maidstone typically costs between £1,800 and £2,500 per square metre, depending on specification and complexity. A modest 20 square metre rear extension might cost £40,000 to £50,000, while a larger 30 square metre extension with high-end finishes could reach £70,000 or more.
A double storey extension costs more in total but delivers better value per square metre. Expect to pay between £1,500 and £2,200 per square metre for the upper floor—less than the ground floor because foundations, groundwork, and roof costs are shared. A 20 square metre footprint delivering 40 square metres of total space might cost £65,000 to £85,000.
In simple terms, going double storey typically adds 50-60% to your build cost while doubling your floor space. If you need both ground floor and first floor space, building them together makes financial sense.
However, if you only need ground floor space, a double storey extension means paying for rooms you don’t require. The lower cost per square metre only matters if you’ll use both floors.
What Space Do You Actually Need?
Before comparing costs, clarify what you’re trying to achieve.
Single storey extensions suit homeowners who need:
- A larger kitchen or open-plan kitchen-diner
- Additional living or family room space
- A ground floor home office
- A utility room, boot room, or storage
- A ground floor bedroom or bathroom for accessibility
Double storey extensions suit homeowners who need:
- Extra bedrooms for a growing family
- An additional bathroom or en-suite
- Bedroom space above a new kitchen-diner
- Home office space on either floor
- Maximum additional space from available footprint
Many Maidstone families find themselves needing both—a bigger kitchen and an extra bedroom. In these cases, a double storey extension delivers everything in one project, avoiding the disruption and cost of two separate builds.
Planning Permission Considerations
Planning rules differ significantly between single and double storey extensions, affecting what you can build and how quickly you can start.
Single storey extensions often fall under permitted development, meaning no planning application is required. Under current rules, you can typically extend 3 metres from the original rear wall for attached houses or 4 metres for detached properties without permission. Larger extensions up to 6 or 8 metres may be possible through the prior approval process.
Double storey extensions almost always require full planning permission. The application process takes around 8-12 weeks and involves assessment of your extension’s impact on neighbours, including overshadowing and loss of privacy. There’s no guarantee of approval, although well-designed extensions on suitable properties usually succeed.
For Maidstone properties in conservation areas—including parts of the town centre and some surrounding villages—additional restrictions apply to both extension types. Properties near listed buildings may also face extra scrutiny.
If speed matters and your project works within permitted development limits, a single storey extension gets you started faster. If you need double storey space, factor the planning timeline into your project schedule.
Impact on Your Property
Extensions change how your home looks and feels, inside and out. Both types bring different considerations.
Single storey extensions are generally easier to integrate visually. A well-designed rear extension can look like it was always part of the house, particularly with matching materials and roofing that complements existing proportions. From the street, many single storey extensions are barely visible.
Double storey extensions have greater visual impact and require more careful design. The additional height and mass must balance with your existing property to avoid looking like an awkward addition. Roof lines, window positions, and material choices all matter more when building two storeys.
For semi-detached properties common in areas like Allington, Bearsted, and Penenden Heath, double storey extensions also affect the relationship with your attached neighbour. A two-storey addition on one half of a semi changes the building’s symmetry and may require particular design sensitivity.
Impact on Neighbours
Your extension affects neighbouring properties, and this influences both planning decisions and neighbourly relations.
Single storey extensions have limited impact on neighbours. They don’t overlook adjacent gardens from height, and overshadowing is usually minimal. This makes planning approval more straightforward and keeps neighbours happy.
Double storey extensions require more careful consideration. First floor windows can overlook neighbouring gardens, creating privacy concerns. The additional height can overshadow adjacent properties, particularly those to the north of your extension. Planning officers assess these impacts, and objections from neighbours can complicate applications.
Before committing to double storey, consider your specific situation. A detached property in Grove Green with generous spacing to boundaries faces fewer issues than a terraced house in Tovil where neighbours are close.
Talking to neighbours early—before submitting any planning application—often prevents problems. Most people appreciate being consulted and may support your plans if they understand what you’re proposing.
Build Time and Disruption
Living through a building project is disruptive, so timescales matter.
Single storey extensions typically take 10-14 weeks to complete, depending on size and complexity. Groundwork, structure, roofing, and fitting out follow in sequence. You’ll lose garden access during construction and may need to relocate your kitchen temporarily if that’s where you’re extending.
Double storey extensions take longer—usually 14-20 weeks for a straightforward project. The additional structural work, first floor construction, and extra fitting out all add time. Scaffolding remains up longer, and disruption extends further into your home as first floor work proceeds.
Neither option is quick, but single storey extensions cause less prolonged disruption. If minimising impact on daily life matters, that’s worth considering.
Which Suits Maidstone’s Housing Stock?
Maidstone’s diverse housing offers opportunities for both extension types.
Victorian and Edwardian terraces around the town centre and Tovil often suit single storey rear extensions, opening up ground floors into modern kitchen-diners. Double storey can work but requires careful design given proximity to neighbours.
1930s semi-detached houses common in Bearsted, Allington, and Barming suit both approaches well. Generous plots often provide space for substantial extensions, and double storey additions can balance well against these properties’ existing proportions.
Post-war housing across Shepway, Parkwood, and surrounding estates varies in suitability. Some properties have ample garden space for either extension type, while others face tighter constraints.
Detached houses in areas like Boxley, Sandling, and the surrounding villages generally offer most flexibility. With space on all sides, both single and double storey extensions can work without significantly impacting neighbours.
Making Your Decision
The right choice depends on your specific circumstances. Consider these questions:
- Do you need ground floor space only, or both ground and first floor?
- Does your budget stretch to double storey if that’s what you need?
- Will planning permission be straightforward for your property?
- How will a double storey extension affect your neighbours?
- Is minimising build time and disruption a priority?
For many Maidstone families needing both kitchen space and an extra bedroom, double storey extensions deliver the best value. For those focused purely on ground floor living—an open-plan kitchen, home office, or accessible bedroom—single storey keeps costs lower and build times shorter.
Getting Expert Advice
Every property is different, and the best choice for your Maidstone home depends on factors specific to your situation. A good builder will survey your property, discuss your requirements, explain the options clearly, and help you make an informed decision before any commitment.
We offer free consultations for Maidstone homeowners considering extensions. Whether you’re leaning toward single storey, double storey, or aren’t sure which suits your needs, we’ll provide honest advice based on your property and circumstances.
Considering an extension for your Maidstone home? Contact us to arrange a free survey and no-obligation quotation.