Single Storey Extension: Costs & Ideas
Add valuable living space with a single storey extension. Explore design options, understand the costs, and learn about planning and building regulations.
Thinking of adding more space to your home but not sure where to begin? A single storey extension could be the answer to add functionality and value to your home without the hassle. This type of extension gives you more room and a more tailored living experience.
A ground level extension is a single storey addition that adds living space, often used for kitchens or living rooms, without changing the height of the building.
With rising house prices and growing families many homeowners are turning to extensions as an alternative to moving. Knowing the ins and outs from costs to planning permissions is key to making informed decisions that fit your vision. Whether you want a cosy kitchen extension or a big wraparound design, knowing the rules and regulations will get you off to a smoother start.
In this article we’ll look at the basics of single storey extensions, from costs to types of extensions to hiring professionals. Get ready to see how this investment will transform your home and meet your needs.
Single storey extensions are the most popular choice for homeowners looking to add more space to their home without the hassle of a two storey extension. They allow you to enlarge rooms such as kitchens or living rooms by extending the original house outwards. This can be to the back, which is known as a rear extension, or from the side, both giving you more space and more natural light with features like Bi-fold doors or large windows.
One of the benefits of single storey extensions is they are Permitted Development Rights so many don’t need formal planning permission, making the planning permission process easier. They can be built right up to 50mm from the boundary.
However building regulations still apply to ensure the safety and standards of the new build. Homeowners must make sure the design respects the original architecture, especially with period properties, and consider the impact on outdoor space.
Despite the ease some larger or more complex plans like wraparound extensions will still need a planning application. The cost of a single storey extension varies widely depending on size, materials and type of extension, flat roof or pitched. So the first step in any storey extension project is to contact the local planning department.
In the world of single storey extensions the financial side is a big consideration for homeowners. The average cost of this in the UK is around £35,000. This is for standard materials and includes a kitchen in the new living space. But the size of the extension will greatly affect this figure. For a small, no frills single storey extension of about 15m² you could pay from £15,000, for a larger and high spec area of about 50m² you could pay up to £100,000.
Current construction costs are around £2,000 per m² for an extension with basic to mid range spec. But in areas like London and parts of the South East this is higher, £2,300 to £2,800 per m² due to economic factors. It’s not just the build itself that affects the overall cost – additional items like a kitchen or bathroom, with starting costs of around £10,000 and £5,000 respectively will also impact the total cost depending on the appliances and finishes you choose.
These figures don’t include professional fees which are an additional 10-15% of the total build cost. This covers services like architectural design and the planning application which could add thousands to your project.
When planning a single storey extension costs can vary greatly depending on size, quality and extras. A side extension in the UK could cost from £15,000 to £25,000 and a rear extension from £25,000 to £40,000. A basic single storey extension of 4m x 5m would cost around £2,000 per m² which is £40,000 for the build and £54,000 including professional fees and VAT.
A double storey extension with the same footprint will cost from £81,000 or 50% more than the single storey. Budget single storey extensions cost around £1,500 to £1,900 per m² and high end around £1,900 to £2,400 per m².
Additional costs are significant, £5,000 for a basic bathroom and £10,000 for a kitchen. And don’t forget the miscellaneous costs like planning fees, a planning application in England will cost around £20.
Remember these are rough estimates and actual costs will vary depending on your project and local prices.
A single storey extension to add extra living space requires careful budgeting beyond the build costs. Key additional costs to consider are the inclusion of a kitchen or bathroom. These areas will add to your budget; a basic bathroom will start at £5,000 and a kitchen at £10,000, depending on materials and finishes.
Professional services will also account for a significant chunk of the costs. Architect fees are typically 3-7% of the build cost, so £2,700 for planning drawings and same for construction drawings. You may also need a structural engineer to determine the roof joist and foundation requirements; their fees will be between £500 and £1,000.
Surveys of the existing property may also be required, fees will be between £500 and £1,500. And professional fees for architectural guidance and building regulations compliance will be around 10-15% of the extension budget. Plan for these additional costs carefully to ensure a smooth build and avoid any financial surprises.
Single storey extensions are the most popular choice for homeowners who want to add extra living space without going for a more complex multi storey project. They are generally less disruptive and more cost effective and can be fitted into the existing layout of a house. There are three main types of single storey extensions: side return, rear and wraparound. Each type suits different needs and property layouts and gives homeowners options.
A side return extension is perfect for properties with a narrow side alley, common with Victorian and Edwardian homes, to increase the width and usability of the house. Rear extensions are the most popular type, extending from the back of the house and a simple way to add space. Wraparound extensions are a combination of side and rear extensions, wrapping around part of the house to add a lot of space.
These types of extensions add square footage to the house and can increase its value by creating modern open plan areas for contemporary living. This could be enlarged kitchen-dining areas, additional lounge spaces or even a home office, all while keeping and enhancing the original character and layout of the house.
For semi-detached or detached homes, especially those with period Victorian or Edwardian houses, a side extension allows you to use the narrow side alley. This extension can add a lot of usable space to the house and room for a modern kitchen or additional living area. The idea of turning what is often underused or dark space alongside the house into a part of the home’s layout is a tempting prospect for many.
The cost of a single storey side extension is between £40,000 and £50,000 depending on the size and finish of the project. When planning a side extension you need to consider permitted development guidelines which state a maximum depth of 3 meters for terraced and semi-detached houses for rear extensions, which may affect the side extension design. Planning permission may also be required and where applicable this can allow you to extend further than permitted development rights.
Rear extensions are the classic home extension, projecting out from the back of the house into the garden. They are the most popular choice for many who want a larger open plan area or a big sunlit room that complements and extends the living space of the original house. They are especially popular for those who want to add a larger kitchen or dining area.
When homeowners develop a rear extension under permitted development rights, detached properties can extend up to 8 meters and terraced and semi-detached homes can extend up to 6 meters without needing formal planning permission. This gives flexibility in design but is governed by height and distance from the original rear wall. Prices for rear extensions vary but are generally between £25,000 and £40,000 depending on the size of the extension, materials and complexity of the build.
Wraparound extensions are the ultimate solution for homeowners who want to increase their property footprint without taking up too much garden space. This type of extension wraps around the side and rear of the house, giving a dramatic transformation that can reconfigure the ground floor layout. Because of the larger scale and extra structural work involved, wraparound extensions tend to cost between £40,000 and £100,000.
Choosing a wraparound extension means a large multipurpose living space that combines the indoors with the outdoors, blurring the lines between kitchen, dining and lounge areas. As this type of extension doesn’t fall under permitted development, you will need to go through the planning permission process with the local planning authority.
A kitchen extension can turn a standard kitchen into a hub of activity in the home, perfect for cooking and socialising. It can include modern appliances, plenty of storage and stylish design elements and often combines indoors with outdoors through bi-fold doors and large windows.
When planning a kitchen extension you may see an integrated dining area which can elevate the whole atmosphere for cooking and entertaining. As kitchen extensions are one of the most used rooms in the house, the design needs to be thought through carefully. Lighting is key and using windows, skylights or bi-fold doors can bring in natural light and make the kitchen more usable.
Prices for kitchen extensions vary depending on the household, the complexity of the work and the materials chosen. But making sure the extension flows seamlessly from the original house and the design is well thought through will make a big difference to the project.
Single storey extensions can add so much extra living space to a house but before you start any project you need to understand and comply with the planning permissions and building regulations. Planning permission may not be required if the extension falls under permitted development rights which allow homeowners to do certain works without full planning permission. These rights are governed by criteria that the extension doesn’t encroach too much on surrounding land or the neighbour’s privacy.
Under permitted development rules, for detached houses a single storey extension can’t extend beyond the back wall of the original house by more than 4 metres and 3 metres for other houses. But larger extensions of up to 8 metres for detached houses and 6 metres for others are possible in non-designated areas as long as the height is 4 metres.
When an extension might affect neighbouring properties the Local Planning Authority will conduct a 21 day consultation period. If objections are raised the homeowner may need to go through a prior approval process to address the concerns. For larger projects that fall outside permitted development a full planning application needs to be submitted to the Local Planning Authority and can’t be done retrospectively.
To do a single storey extension you need to be mindful of the properties next door as the Local Planning Authority will consult with the adjacent neighbours for 21 days to consider the impact on residential amenities such as loss of daylight or privacy. If the extension doesn’t comply with the permitted development criteria for size and design planning permission is required and not complying with this will mean legal enforcement.
Homeowners looking to use permitted development rights need to check that their proposed extension meets all the conditions. It’s highly recommended to apply for a Certificate of Lawfulness if you think your project falls under permitted development. This certificate is proof that your project is lawful. And you need to submit a prior approval application through the neighbour consultation scheme if you’re building an extension bigger than what’s allowed under permitted development.
The Party Wall Act is an important consideration for homeowners in England and Wales doing single storey extensions especially if they’re next to a neighbour’s property. This act requires homeowners to serve notice to their neighbours if the construction involves a shared wall or boundary feature.
The Act covers shared walls between semi-detached or terraced houses to garden walls straddling boundaries and extends to excavation work near neighbouring structures. In some cases a Party Wall agreement may be required especially if the construction involves significant changes like installing steel supports or foundational work that will affect the structural integrity of the adjacent buildings. As well as being a legal requirement pre-emptive communication with neighbours about the construction can help maintain good relationships and potentially reduce objections to the plans.
Local Planning Authorities use the 45-Degree Rule as a guide when assessing single storey extension proposals. The rule is to protect the neighbours’ access to light. It’s measured by drawing a line at 45 degrees from the midpoint of the nearest ground floor window of the adjacent property beyond which you can’t build.
You must follow this rule; if you don’t you’ll get objections from neighbours and potentially planning permission refusal. The 45-Degree Rule applies to single storey extensions and you must consider it if you want to extend your living space. The rule protects the neighbours’ right to light and ensures that new build doesn’t deprive existing properties of natural light and therefore the residential amenity.
Material Selection for Your Single Storey Extension
Choosing the right materials for a single storey extension is important for permitted development and matching your house. The key is to choose cladding that matches your original house to make the planning permission process easier especially for period properties.
Timber cladding is a popular choice as it looks great and is durable. But make sure it matches the existing materials of the house or you’ll have problems with planning permission.
An alternative is aluminium cladding. It’s lightweight and durable and a sustainable option that will improve the energy efficiency of your living space. Both timber and aluminium have great insulation properties so will improve thermal and acoustic performance in your extension.
When it comes to maintenance ongoing costs are a factor. Different materials will require different levels of maintenance over time and that will add to the storey extension cost. Consider your budget and think about the long term maintenance costs of your chosen cladding to make sure it’s a viable option for years to come.
Material Considerations:
A single storey extension is a big project that will add value to your house. Homeowners can expect the extension to take 2-4 months to complete, 3-4 months is a more conservative estimate that allows for unexpected delays.
In the early stages of the project which is usually in the first 2 weeks the focus is on site preparation. This includes the essential tasks of excavating footings and laying foundations, getting everything ready for the rest of the build.
Several factors can extend the 8-12 week build period of a single storey extension. Project size and complexity will play a big part, as will building regulations and local planning department requirements. Extra care needs to be taken during the planning permission process especially if the property is a detached house or detached property; these will impact the timeline.
Please note that while single storey extensions are quicker to build than a 2 storey extension they are still variable. Weather, scheduling conflicts and material issues can all extend the timeline. So prospective timelines for a single storey extension should be treated with flexibility.
A single storey extension is the perfect opportunity for homeowners to adapt their home to their changing lifestyle needs such as the growing trend of remote work that requires flexible living spaces. The beauty of these extensions is their flexibility; using modern materials and clever designs can turn a simple addition into a feature of the house. Current designs are moving towards creating smaller, separate zones within an open plan to accommodate different activities including workspace requirements.
Extension design is also about connecting different areas of the house. By cleverly linking spaces like the kitchen, living room and outdoor area an extension can make communal living much easier. A well thought out layout can create a seamless transition between these areas and increase the sociability and functionality of the space. Natural light is key to designing a single storey extension. Thoughtful placement and choice of windows and doors will not only bring more daylight into the extension but also create inviting and lively interiors.
Roofing is a key design element for single storey extensions and will affect both aesthetics and functionality. Of the roofing options available flat roofs are a popular choice, they are budget friendly and quick to install; they are great for bungalows. If you want a more robust and long lasting option pitched roofs are worth considering although more expensive than flat roofs they are more durable and can withstand harsher weather conditions.
Skylights in different roof styles is a popular way to bring in some daylight into an extension and create a sense of openness. For flat roofs roof lanterns are an architectural solution, adding height and more natural light into the internal space. Each roofing option has considerations of cost, installation and maintenance so make sure to choose the right roof for your extension project requirements and design goals.
Window styles can affect not only the look of a single storey extension but also how it relates to the outdoor space. Bi-fold and sliding doors are the current trend, a sleek way to connect the internal space to the external areas and extend the living space into the garden. The return of Crittall style windows and doors adds a touch of sophistication to both modern and period properties, with beautiful designs that combine strength with style.
Modern single storey extensions are using feature windows where possible where design allows for window seats that maximise views and garden enjoyment. The design and frame of windows and doors should be coordinated with the interior decor to look cohesive. Glass extensions although visually pleasing are often outside of permitted development and may require a planning application as they are a change of material from traditional brick construction.
Putting large glass windows in a single storey extension is a clever way to bring in more natural light into the home which can improve the ambiance and health of the people living there. It’s often recommended that the glazing of a room should be at least 15-20% of the floor area to avoid any dark spots and allow free flow of daylight and uplift the whole living space.
Harnessing natural light can reduce energy costs and improve the well being and lifestyle of the occupants. Thoughtful placement of windows and doors can create beautiful views and bring in more daylight and add to the beauty and functionality of the extension. Maximising daylight requires careful planning and takes into account many factors including roof styles where flat roofs are a more cost effective way of bringing in lots of natural light.
Adding a single storey extension to your home meets the need for more space and adds value to your property. These are a popular type of home improvement as they can be built quicker than their double storey counterparts. Whether you want a larger kitchen or a new living area this is a good investment for any detached property.
Most single storey extensions especially rear extensions are Permitted Development, so the planning permission process is simplified. They allow for a seamless extension of the original house often with Bi-fold doors or Flat Roofs to bring in natural light and connect to the outdoor space.
You can design the extension to suit various utilities. Open-plan spaces are popular as they are the modern way of living. A well done storey extension not only makes a detached house more practical but also makes the home more beautiful and more saleable.
Extensions that work with period properties and new build homes alike prove that single storey extensions are timeless.
In summary, choosing a single storey extension is a clever move for homeowners who want to add more living space without the cost and hassle of moving to a new home. These extensions bring in not only more space but also more natural light and make the space more beautiful and functional. Just remember the planning and design phase can take up to a year so be patient and plan carefully.
To simplify the process homeowners should look into Permitted Development Rights to bypass the full planning permission process but this is subject to certain conditions and local guidelines. This extension brings benefits in terms of extra space and potential for larger kitchen or more flowing living areas and can increase property value by 5-8%.
If you are considering this type of extension keep designs simple and use existing infrastructure to save costs. Simple configurations, cost effective materials and putting new utilities near existing ones can save you a lot.
Carefully consider your needs, assess your property for a single storey extension and consult with professionals for planning permission and building regulations to ensure a successful house extension project.
Checklist for Your Single Storey Extension
Choosing the right builder is key to a successful home extension. At Danesfort we deliver quality on time and on budget. We have extensive experience working on home extensions in the London area.
Danesfort ensures all projects comply with planning permissions and building regulations. We offer clear contracts that outline scope, timelines and payment terms so you’re fully informed from start to finish.
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