Home Extensions: The Ultimate 2026 Guide
Introduction
If you’re looking for a way to improve your property’s value and add more room, extensions could be a good idea.
But what is involved in getting an extension? How much planning needs to be done? How much does it cost?
Don’t worry; in this guide, you’ll find out everything you need to know about extensions, including the different types of extensions plus the potential costs and fees.
What is an extension?
Extensions are some of the most popular home improvements projects, because they allow you to add more space to your home. They are also often insulated and can be customised to your tastes.
This flexibility can save you from needing to move to a bigger home, but there are some potential downsides like the price and heavy planning involved.
When should you extend your home?
Moving house can be expensive, not only because of the actual price of your new home but also agent and legal fees, and things like stamp duty.
For the same price, or perhaps even less, you could opt for extending your home instead. For situations like expecting a new family member, you might not need to go through the stress of moving.
You might also choose to have an extension to raise the overall price of your property.
How much does an extension cost?
The cost of your extension will vary on the size, materials used, and whether it needs to be an extension of an existing room or a whole new room.
- Orangery/Conservatory: £10,250 – £16,750
- Shell loft conversion: £22,500 – £37,500
- Garage conversion: £10,000 – £20,000
- Cellar conversion: £40,000 – £50,000
- Side extension: £30,000 – £50,000
- Single-storey extension: £40,000 – £140,000
You should always compare your options when you are deciding what kind of extension is right for you, as well as which company to go with.
Planning Permission
As this is an extension, not a conservatory or greenhouse, for example, you will need to take planning permission and regulations into consideration.
Here are some common rules to remember:
- You can’t build an extension that covers over half of the land around the original property.
- The roof can’t be made to be higher than the roof of your property.
- Maximum extension of a single storey at the back of your home can’t be more than 3m for an attached home or 4m for a detached home.
- The limit was increased to 6m for an attached house and 8m for a detached house after 2019.
- A roof pitch that is higher than a single storey needs to match the existing house.
- There needs to be no balconies, verandas or potentially anything like a raised platform.
There may be many more rules that apply to you, depending on your situation, so it is always advisable to speak to specialists to check what you need to do. Plus, committing to an extension that is technically ‘illegal’ would mean that local authorities are allowed to destroy it.
Building Regulations
Aside from planning permissions, there are also building regulations to think about. These regulations help you to know if it is safe for you to build your extension.
You need to get architectural plans drawn, and it will usually be approved by your local council before you can get started. Also, your contractor will need to create a safety plan to ensure that the site is safe for all of the workers.
Design
You can usually work with an extension company to help you design your perfect extension, whether it is adding a meter to an existing room or creating a whole new place like a lounge or kitchen.
They will often take building regulations and planning permissions into consideration, which can save you a lot of time when getting an accurate quote for your project.
Alternatively, an architect or firm could help you to design your extension if there is a particular style that you want.
Materials
There is usually a wide range of materials available, including:
Frame
- Brick
- Wood
- uPVC
- Metal
Windows
- Self-cleaning glass
- Solar or heat-reflective glass
- Laminated glass
- Triple-glazed glass
- Curved glass
- Toughened glass
- Frosted glass
Floors
- Tiles
- Wood
- Concrete
- Epoxy
Building
The preferable way to find a builder is by searching a reputable website, such as Trust a Trader or using the TrustMark website. These traders will be vetted by the government or have reviews from customers.
This can help you to make an informed decision about which builders might be best for you. Another option is to go with a well-known brand, such as Everest, that will not only supply your design and materials but also install the structures.
Top 10 Extension Companies
1. Simply Extend
- Type:
- Extension company
- Offers:
- Extensions
- Google Score:
- 4.4/5
Simply Extend has over 10 years of experience designing side, wrap-around, and rear extensions. Their extensions are designed to be 100% bespoke to match your needs. They also offer fixed prices and a 10-year warranty to ensure that you are comfortable with your purchase.
There’s also a range of extension styles, such as modern and minimalist. You can also opt to have fittings installed if you decide to convert or extend a room into a new kitchen or living room.
2. HET Windows
- Type:
- Extension company
- Offers:
- Extensions
HET Extensions is a Hertfordshire-based company that provides high-quality extensions, with over 1,500 home improvements to their name and over 25 years of experience.
They can help you design your extension right from the initial free consultation all the way to completion. In HET Extension’s case studies, you can find evidence of their work from corner extensions to single storey renovations.
3. The London Kitchen Extensions Company
- Type:
- Extension company
- Offers:
- Kitchen extensions
- Google Score:
- 4.6/5
The London Kitchen Extension Company specialises in designing and installing kitchen extensions.
Based in Wandsworth, the company can create designs to match your aesthetic needs. On Trusted Traders by Which?, they have many positive reviews stating excellent customer service and products.
4. Apt Renovation
- Type:
- Extension company
- Offers:
- Extensions, renovations, conversions
- Google Score:
- 4.5/5
Apt Renovation offers a wide range of services and products, such as extensions, renovations, and conversions for lofts and outside spaces. Their extensions can be used for living spaces, conservatories, and kitchens.
On their Google page, the reviews say that they provide a professional and honest service.
5. Dreton
- Type:
- Extension company
- Offers:
- Extensions, conversions
- Google Score:
- 5/5
Dreton offers bespoke extensions that can be used as lounge spaces or kitchens and extra bedrooms.
Their extension comes with a 10-year guarantee and is constructed by experienced and accredited professionals.
6. Moduroom
- Type:
- Extension company
- Offers:
- Extensions
Moduroom has over 20 years of experience in the extension industry, providing their services to those in the UK mainland, the Channel Islands, and Northern Ireland.
Their extensions feature slimline designs and range from converted family spaces and ground floor extensions to second storey extensions and garden rooms. They provide fast construction times, a fully managed design service, and high-quality materials.
7. Plus Rooms
- Type:
- Extension company
- Offers:
- Extensions and conversions
- Google Score:
- 4.8/5
Plus Rooms provide home extensions across London and Surrey. They specialize in side, side return, rear, wraparound, and flat roof extensions.
Their site has the average costs for their services. For example, a flat roof medium rear extension can cost approximately £115,000.
8. MoreSpace
- Type:
- Extension company
- Offers:
- Extensions, conversions
- Google Score:
- 4.8/5
MoreSpace is a highly rated extension company with many customers stating that construction was quick, and the team is friendly and helpful.
Most of their extensions have quick completion. The company also says they work closely with suppliers and interior designers to craft the right fit for a client’s home.
9. LCCL Construction
- Type:
- Extension company
- Offers:
- Extensions and conversions
- Google Score:
- 4.9/5
LCCL (Loft Conversion Company London) Construction is primarily based in London and specialises in home extensions and renovations, and loft conversions.
Their house extensions offer end-to-end services, including consultation, architecture, survey, and construction (plumbing and electrical installations). They also offer free consultation calls and staggered payments.
10. Modplan
- Type:
- Home improvements company
- Offers:
- Extensions, conversions, refurbishments, project management
- Google Score:
- 3.3/5
Modplan offers a range of home improvement services, such as extensions, loft conversions, and renovations.
They have already managed over £4,000,000 worth of house extensions, which are made from high-quality materials. Their customers state that the Modplan team is professional and friendly.
Conclusion
Home extensions can be a costly undertaking, depending on what room you are trying to extend or if you’re building a new one. But with careful planning and the right supplier, you might find a service that will fit your budget.
Before deciding on which supplier to go with, it’s best to compare options. Check out the tool at the top of the page, or you could take a look at the guides on this site.
