House Extensions: Designs & Costs UK
Enhance your home with a custom extension. Discover various house extension designs, building regulations, costs, and planning tips for your project.
We all need more space, whether it’s a growing family or changing lifestyle. House extensions are a practical solution, without the need to move. Knowing the different types of extensions and what they mean can help you make informed decisions.
Home extensions add space and livability, single or double storey and loft conversions. Can be tailored to your needs, extra bedrooms, open plan living areas or home offices.
With so many options available, ground floor, first floor, wrap around, which one to choose depends on your individual circumstances and home layout. And what type of house you have, semi detached or detached, plays a big part in the extension process.
This article covers the basics of house extensions, costs, finance, design, environmental impact and regulations so you can get started on your extension journey.
House extensions give homeowners the flexibility to adapt their living space to their changing needs and lifestyles. They can add value to your property by adding functional rooms and often include modern features like bi-fold doors and Velux windows to bring in lots of light. There are many options for those thinking of a house extension project, each with different size and complexity.
Types of extensions:
Planning permission and building regulations apply to all types of project. Many house extensions can be built under permitted development rights, so formal planning consent isn’t always required if they meet certain criteria. When planning permission is needed, you need to submit a planning application to the local authority. The work must comply with building regulations to meet safety and quality standards.
Each type of extension has its own design considerations, costs and benefits, whether it’s for extra living space, bedrooms or a bigger kitchen. Knowing the different types of extensions can help you make informed decisions about your own house extension project.
Ground Floor Extensions are popular for homeowners who want to add to their kitchen or living space, to create an open plan area that leads into the garden. This type of extension is ideal for those with mobility issues, as it’s easier to navigate the house. They often include design features like bi-fold or sliding doors to blur the indoor and outdoor spaces.
For terraced houses or semi detached homes the maximum depth of a rear extension is 3m, and for detached homes 4m under permitted development rights. Many ground floor extensions can be done without formal planning permission, as long as you meet the limits and conditions of permitted development.
First Floor Extensions add space to the upper levels of the property, such as extra bedrooms or expanded bathroom areas. These can be tricky for terraced houses as they can obstruct neighbours’ light or views. Detached and semi-detached homes have more flexibility, with the possibility of larger two storey extensions.
You must comply with building regulations and planning departments have specific considerations for first floor additions to ensure the extension fits in with the surrounding properties. These extensions can be a good solution if you need extra living space without impacting the garden.
Rear Extensions are popular for homeowners who want to extend their original house without changing the front of the house. Single storey rear extensions can be extended up to 4m beyond the back of the original house, and for terraced and semi detached homes 3m.
You need to be aware of the maximum heights for these structures: 3m at the eaves and 4m overall. You also need to make sure any new materials used match or complement the existing building, in accordance with Building Regulations and local development guidelines.
Using often neglected space alongside the property, Side Extensions are a great way to add functional square footage like a bigger kitchen or utility room. They should match the property and can include design features like roof windows or French doors to bring in natural light and ambiance.
The restrictions on side extensions limit the height to 4m and the width to no more than half the width of the original house. They are not permitted on designated land. Always check and comply with local development rules to avoid any issues.
Wrap-Around Extensions can totally reconfigure a property by combining side and rear extensions for extra space. Practical and potentially cost effective, these extensions offer design flexibility and connection between old and new areas of the house, from kitchen extensions to open living spaces.
While this may seem like a big project, proper planning and working with professionals can result in a beautiful and bespoke addition to the house that meets the family’s needs. Like all extensions, it must comply with planning permission (if required) and building regulations to be legal and structurally sound.
Extending your home can be a great way to add more living space and increase the value of your property. But the planning and execution of a house extension project can vary depending on the type of property you own. Whether you live in a semi, terraced or detached house, each has its own considerations, from planning permission to building regulations and development rights. Knowing the specifics of your property type will help the project run smoothly and you make informed decisions along the way.
Semi detached homeowners extending must consider the specific restrictions and opportunities that their property type brings. Using permitted development rights can speed up the planning process but you still need to check these rights with the local planning authority as there may be local exclusions or variations to the rules. Making sure the design of the extension doesn’t impinge on the privacy or enjoyment of the neighbouring properties is another key consideration as this could lead to disputes or the need for party wall agreements. The choice of materials is not just an aesthetic decision but could also be subject to conservation area or listed building regulations so careful selection is needed to preserve the architectural integrity of the area. A well designed extension should not only give you the space you need but also match the semi detached home and increase the value of the property.
Extending a terraced house requires careful consideration of the surrounding properties and the impact on your neighbours. Privacy, access to natural light and the implications for shared structures like party walls are top of the list when planning a terraced house extension. Access is a big issue in terraced houses as moving materials and waste is difficult in densely built up areas. A party wall agreement is essential when structural changes affect shared walls so you are compliant with the law. Check on any additional restrictions early on in the planning phase, including the potential for extra costs tied to site specific challenges, is key to a successful project. Permitted development rights can be a quicker route for extending your home but as always this is subject to local development rules and should be checked before you start.
Detached homeowners have more scope and flexibility when extending as they have fewer restrictions on the neighbouring properties. Under permitted development rights – subject to checking with your local authority – you could extend up to 8m to the rear of the property. But you can’t use more than half of the garden space around the house and the height of the extension must match the existing roofline. Technical surveys and getting building consent are still part of the process to ensure the finished extension complies with the local authority guidelines and planning applications if needed. Detached homes may have a more relaxed regulatory process than other types of homes but careful planning and following the development rules is still key to a successful house extension project.
A house extension brings the promise of extra space and potential increase in value of your property. But the cost involved is significant and should be understood before you start. In London a standard house extension starts at around £2,000 per square metre. This can vary depending on the project. For example a ground floor rear extension can cost between £40,000 to £100,000. If you’re looking at a two storey extension it could be £70,000 to £150,000.
For those looking for a more budget option flat pack extensions offer a different pricing structure. £750 to £3,600 per square metre depending on the quality and design. Basement extensions start at around £975 per square metre for waterproofed areas but can quickly get more expensive if structural work is required.
If you want to extend up rather than out you can start from £1,800 per square metre for a basic loft extension with rooflights where you don’t need to alter the existing roof structure.
When budgeting for a house extension in London the average cost is between £40,000 to £50,000 depending on the type of house and the complexity of the extension. Flat pack extensions offer a wide range of pricing with basic options starting at £750 per square metre and going up to £3,600 per square metre.
For a semi detached or detached house a ground floor extension will be £40,000 to £100,000, a two storey extension £70,000 to £150,000. A side extension for a semi detached house will be £50,000 to £90,000 and a front house extension will be £1,500 to £3,000 per square metre.
The costs of a house extension are influenced by many factors. The base cost of £2,000 per square metre will vary depending on the design and structural requirements. For example a simple house extension in London could start at £40,000 for a 20 square metre extension.
Other variables such as the size and style of the extension, the amount of glazing required, the roof choice will all impact the final cost. Before any work starts you’ll need to pay an initial fee for the planning applications, £206 unless the extension is under Permitted Development. In that case you can avoid this fee but it’s recommended you get a Lawful Development Certificate to prove the extension complies with the development rules.
The details and quality level in the architectural plans will determine the final cost. Without these plans builders often won’t give you a fixed price, so it’s essential to get everything prepared before you start any extension project.
When you start a house extension project interior design is key to ensure the new space fits your lifestyle and maximises functionality. A well designed extension can give you more than just extra space it can improve the quality of living in your home. Natural light is key, it affects the usability and ambiance of the room especially in open plan areas that are used during the day. This can mean positioning windows and skylights to light the space during peak usage times.
A professional interior designer can be very helpful in navigating these considerations. They can help you avoid costly mistakes by having a well thought out plan from the start. Designers can propose bespoke spaces like a home office or children’s playroom that will serve the household’s specific interests and needs. They can turn your concepts into practical designs so both the aesthetic and practical of your vision comes to life.
Also, incorporating eco friendly elements into your house extension is becoming more and more important. Sustainable design reduces your home’s environmental impact and can also give you operational savings in the long run. A professional can guide you through the eco friendly options and make your extension more sustainable and desirable.
Oversights in a house extension can lead to regrets and complications that affect the functionality and harmony of the new space. One common mistake is not fully planning the final layout and ending up with poorly placed fixtures or furniture. The design should flow into the original house and have similar flooring and wall colours to avoid a jarring effect.
Not considering natural light can compromise the comfort and usability of the extension so you need to consider the daily movement of light for window placement. Also you need to understand and comply with the planning restrictions that applies to your property type to avoid viability issues in the approval process.
Consulting with specialists like architects and engineers is crucial to avoid costly design mistakes and compliance with building regulations and development rules. Not anticipating potential legal obstacles like planning permission, development rights or party wall agreement can delay the project. Underestimating the cost of professional consultations can blow the extension budget.
Making the most of the new square footage in your house extension is as important as the extra space itself. Smart storage solutions can declutter the area and make it feel more spacious and functional. Clever architectural features like fully glazed lean to roofs or slim framed pivot doors can not only flood the space with natural light but also connect you to the outdoors.
A broken plan layout can help separate zones without the need for walls. It can turn larger spaces into smaller functional areas while still feeling open and airy. By incorporating these design strategies you feel more open and connected to the outdoors.
Finally be mindful of your neighbours right to light and privacy. Thoughtful planning will create a harmonious environment for all parties involved and prevent potential disputes. By using design strategies that prioritise ecological design, connectivity and neighbourly boundaries your house extension will be the perfect example of modern living.
House extensions can add extra space and value to a property. But there are common pitfalls to be aware of to make the extension successful.
House extensions give you extra space but also an opportunity to improve the functionality and flow of your living space. Smart storage solutions are key to saving floor space and organisation. Built in cabinets and multi functional furniture can hide clutter and make your extension feel bigger and more open.
Natural light is key to making any room feel spacious. Architectural features like a fully glazed lean to roof or slim framed pivot doors can flood your extension with daylight and connect the indoors to the outdoors. Glass is a clever way to blur the boundaries and make your extension a bright and welcoming space.
A broken plan layout is another way to optimise space. By dividing larger open areas into separate zones for different activities you can create the illusion of extra space and a sense of structure without losing the openness of your extension.
Don’t forget to consider your neighbours. Make sure your plans respect their right to light and privacy to keep the peace. By thoughtful planning and design your house extension can be a versatile light filled space that improves the quality of life.
When planning a house extension project environmental impact is becoming more and more important. By focusing on sustainability and using eco friendly building practices homeowners not only help the environment but also get long term benefits like lower energy bills and better home comfort. This commitment to eco friendly development is reflected in the materials chosen and the build methods used during the extension.
Eco friendly building practices are key to a house extension that is both environmentally friendly and cost effective. To achieve this energy efficiency should be a core principle in the design and build process as per building regulations. This means high performance insulation, low energy lighting and thermostatic valves on new radiators.
Going for a ‘fabric first’ approach is a smart move which focuses on maximising the building’s energy efficiency through its fundamental design and materials. This approach reduces the need for additional eco friendly features to achieve the desired energy performance but doesn’t rule out their use. Homeowners can further reduce their environmental footprint by investing in bigger ticket items like solar panels, ground source heat pumps, green roofs and rainwater harvesting systems. Even smaller tweaks like orientating windows for maximum solar gain can make a big difference to the overall energy efficiency of the extension.
Talk to architects and builders early on and they can help you identify the best strategies and materials for a sustainable build. They can guide you through the options that fit your extension design and sustainable building practices.
The choice of sustainable materials is key to reducing the environmental impact of a house extension. The building regulations are a guide, setting minimum standards for insulation in walls, floors and roof spaces and encouraging energy efficient glazing and lighting. High levels of insulation with advanced glazing like double or triple glazed windows are critical to prevent heat loss and reduce the need for artificial heating and lighting.
Sustainable materials affect not only the thermal performance of the extension but the environment as a whole. Renewable, recycled or sustainably sourced materials can reduce the carbon footprint of the build. When designing the extension consider the glazing orientation to maximise natural heat sources and the building’s envelope.
It’s important to get these decisions about energy efficiency into the design stage so the builders can incorporate all the necessary measures for a sustainable build. By choosing eco friendly materials and energy efficient designs you can reduce the running costs of your extension and do your bit for the planet.
Planning and regulations are a key part of any house extension project. In the UK homeowners must adhere to a set of planning rules and building regulations which vary depending on the type of property, terraced, semi detached or detached. You need to know if your project falls under permitted development rights as this can mean you don’t need to submit a full planning application. But getting a lawful development certificate is often recommended for peace of mind and for documentation purposes.
When planning larger rear extensions – one which extends up to 6 meters from the original house for semi detached properties or 8 meters for detached homes – you need to apply for prior approval, which is a separate process from permitted development rights. For terraced homes extensions under 3 meters are permitted development but larger ones will need to notify the council and possibly do neighbour consultations as part of the planning application process.
Costs are part of the planning stage. You need to plan for expenses not just for the build but also for architect and professional services. This can include estimates for planning permissions and architect fees. A full planning application will cost around £4,000 and building regulations approval around £6,000. This highlights the importance of a thorough and informed approach to extension projects to ensure you are legally compliant and financially prepared.
Permitted development rights give homeowners a quick and easy way to extend their homes without planning permission as long as the proposed structures meet certain conditions and size limits. PD covers a range of home improvements including but not limited to rear extensions, single and two storey extensions, side extensions, loft conversions and some alterations to windows, cladding and garden structures.
Extensions under PD must comply with national government criteria but these can vary from one local authority to another. It’s common for homeowners to find out that their desired extension exceeds the PD criteria and so a full planning application is required. While PD rights can make things easier, it’s essential to check with the local council to confirm all the regulations are met.
You must follow the rules. Here are the criteria that apply to extensions under permitted development:
Homeowners should check the extent of their PD rights before starting work to avoid any legal issues from non compliance.
Building regulations approval is a requirement for house extensions and means full building control drawings that show compliance. This will incur costs such as £700 for the building regulations fees and can include professional fees up to 10% of the build cost for contract administration and inspection services.
In the UK extensions must comply with the building regulations and where relevant local planning and the Party Wall Act especially if you live in a semi detached or terraced house that shares a wall with a neighbour. Ignoring or breaching these regulations can be risky and the local council can take enforcement action to make you modify or even demolish the extension.
While the building regulations guidance is similar across the UK, local variations can exist so it’s essential to seek expert advice. Working with a qualified architect and a competent builder is recommended to ensure both the design and build phases meet all the regulations so you get a compliant and quality addition to your home.
Starting a house extension begins with having a idea of what you want to add to your living space. To get started think about the area of your home you want to extend. This could be an extension of existing rooms such as a kitchen extension or a bedroom above a garage. Once you have a clear idea of where you want to add space it’s time to get professional help.
One of the first things you should do is consult with a home extension specialist. Their expertise and experience can help turn your ideas into extension plans and ensure planning permission and building regulations compliance for your area. A home extension specialist can work with you to explore design options and maybe come up with innovative solutions to work with your existing layout to give you better living space with minimal build.
Consider what type of extension you want. Single storey extensions are popular for homeowners who want to add to their living space without changing the overall shape and look of the original house. They can be quicker to build and less intrusive than two storey extensions or more complex wrap around extensions.
During your initial consultations with aa home extension specialist make sure to take into account the needs and wishes of all the people in the household. Getting everyone’s input into the design will mean a more functional and harmonious extension. Remember this is about improving life for everyone who lives in the house.
Choosing the right builder is crucial for the build of your house extension. Your builder will be turning the architect’s designs into reality so make sure you choose a competent and reputable professional or company.
When choosing a builder make sure they are aware of the building regulations and legal requirements for your project. Always check their qualifications and experience especially with projects similar to yours such as rear extensions or loft conversions.
Also get several detailed quotes to compare. These quotes should break down all the costs involved in the project including materials and labour. Don’t be tempted by the cheapest quote – the quality and reliability of the builder is key to the long term success of your extension.
When choosing builders and contractors consider:
By doing this you will feel more in control and the extension process will be smoother.
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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