House Extension Ideas: 30 of the Most Amazing UK Home Extensions

Extending your house is a sure-fire way to add light, space and value to your property – but how can you inject a little personality into your extension's design? Take a look at Build It’s roundup of the best UK house extensions to inspire your project

by Sander Tel

27th October 2023

Looking for house extension ideas? Extending your home is a great opportunity to get the space you need while adding some wow-factor design flair. Whether you’re eyeing up a contemporary open-plan kitchen-diner or a spacious living area, there are several vital factors to consider if you want to create an inviting and practical extension that blends well with the existing house.

From ultra-modern designs with expansive glazing to more traditional structures that blend seamlessly with the existing home, a well-planned house extension has the potential to turn even the most modest properties into a comfortable, stylish and light-filled home.

Although, with so many different finishes and structural methods to choose from, deciding on your extension’s design can take some careful thought. So, here we have put together a collection of the UK’s most amazing house extensions that will be sure to inspire your next project, alongside some top tips from the experts.

1. Sleek & Modern House Extension

A distinctive blend of materials characterises this extension design by Adam Knibb Architects. The home – positioned at the edge of the South Downs National Park – has undergone a complete refurbishment with a new rear addition that allows a greater connection between the house and garden.

Photo: Martin Gardner

Vertical timber fins feature on the upper storey, harmonising well with the traditional brick facade while still offering a visible contrast.

Photo: Martin Gardner

On the ground floor, sliding doors pull away from the corner for a bright, exposed interior – which continues through to the newly open-plan kitchen-diner and snug zone.

2. Spot the Difference in this House Extension

Yard Architects drew on this property’s 1930s roots to formulate a plan for its interior redesign and new extension. The clients were after additional space to make room for a family-friendly and sociable kitchen-living-dining area. The home’s location within a conservation area, though, called for a sensitive scheme that would enhance the original property’s character.

Photo: Richard Chivers

A curved wall to the rear mimics the bay window at the front of the property, and the green tiling references the home’s charming green window cills. Crisp white render flows seamlessly from the main house to the extension for a cohesive look, and glazed doors with dark frames add contrast.

Learn More: How Much Does a House Extension Cost? Real-Life Extension Costs, Ideas & Budgets

Open-Plan Home Extension Design

Paul Archer Design completed a knock-down and rebuild extension project to provide this urban home in Hampstead with a breath of fresh air. Inspired by the clean lines and shapes of Scandinavian design, timber sits at the heart of this project, with wooden floors, ceilings and detailed joinery adding a minimal yet sophisticated touch.

Simple & Sophisticated Home Extension Design

Photo: Helen Cathcart

Large rooflights and full-height glazed doors allow light to travel throughout the entirety of the ground floor. Hipped structural beams have been painted with a soft pastel green to offset their industrial appearance and enhance the home’s bright, calming character.

EXPERT VIEW Designing an extension with personality

Simon Graham, director at Yard Architects, shares his thoughts on creating an extension that suits your home, style and budget

Do I need planning permission to create a characterful house extension?

Planning-wise, the two routes to extending a home will either be under permitted development (PD) or by submitting a full planning application. You can do plenty under permitted development, but restrictions can sometimes be tricky to navigate, so consult your local authority or get plans approved in writing first.

If you’re applying for planning permission, think about your design intentions. Are you doing something different for the sake of wow factor? Or perhaps your scheme is informed by the house’s current architecture? Taking elements from the existing home and blending them into your scheme is a good way to tell a story that’ll paint clearer pictures to planners.

How can you add wow factor to a smaller house extension project?

If you’re limited with space – as with most side-return extensions, for example – focus your budget on innovative architectural features that’ll make the extension feel as big as possible.

Think about clever ways you can incorporate smart storage features to save on floorspace or glazing to maximise daylight. For instance, you may choose to create a fully-glazed lean-to roof or add a slim-framed pivot door that blurs the boundary between your home’s indoor and outdoor zones.

Most will favour the idea of knocking down walls to create a bigger, open-plan zone, but think about how you’ll use this space in the future. Consider a broken-plan scheme that’ll divide a bigger space into smaller chunks, making the newly extended home feel bigger.

What are some budget-friendly ways that an extender can put their own stamp on a project?

There are plenty of affordable ways you can add personality to a new extension. A good place to start is with colour! Pay attention to architectural features such as internal beams or columns, which can be painted any shade you like for added visual interest or to suit other aspects of your home’s design.

Being clever with ordinary, affordable cladding materials can also yield impressive results. Brick, for example, can be laid in multiple patterns – from vertical to herringbone – each carrying a distinctive personality that’ll be sure to add character. Think about extending these materials into your garden, such as on the patio, for an impressive, seamless look.

4. Light-Filled Basement & Rear Transformation

Fraher & Findlay architects transformed this Edwardian house with a basement renovation and rear extension – improving the relationship between the ground floor, garden and subterranean living area.

Photo: Chris Wharton

The home was extended outwards minimally to provide just enough space for a newly-designed, U-shaped oak staircase, which doubles as an open shelving area and lightwell. The positioning of the new addition and staircase allows natural light to flood the new basement area.

Photo: Chris Wharton

A sensitive palette of materials was used to retain the home’s traditional charm. This involved a combination of red bricks, laid vertically for visual interest, and green-framed windows and doors with arched detailing.

5. Colourful Copper-Clad House Extension

Butcher Bayley Architects designed this copper-clad extension to a mid-terrace house in a Cambridge conservation area. Its bold, vibrant design reflects the young, modern family’s personality, with details such as handmade terracotta tiles inspired by the owner’s Italian childhood. The addition’s stand-out feature is the eye-catching copper cladding, inspired by the clients’ love for a nearby university building.

Photo: Matthew Smith

Overhead glazing provides abundant natural light throughout the day, and a window seat makes the perfect spot to relax. Outside, a planted roof provides a view of greenery from the house’s upper floors, balancing out the contemporary architecture.

6. Sympathetic House Extension with Wow-Factor Glazing

The Old Rectory used to be a nursing home in the 1980s but its structure dates back to the Victorian times. It was completely dilapidated and in desperate need of an overhaul until a family spotted the build’s potential.

Photo: FRENCH + TYE

They commissioned Gruff Architects to transform the interior and demolish the rear addition, replacing it with a new, contemporary structure. The rear elevation holds a spacious kitchen-diner perfectly suited to modern family living, establishing a great connection between the home and garden.

Photo: FRENCH + TYE

Light floods the extension through arched and pill-shaped glazing – by IQ Glass – which references the home’s period design details, such as the grand hallway arcs.

More Ideas: 31 Amazing Window Design & Feature Glazing Ideas

7. Charming Oak Frame Addition

The build system you choose for your extension project may influence how it looks and feels. Building with oak creates the perfect opportunity to leave the skeleton exposed, meaning you can transform your extension’s structure into an amazing design feature. Oakwrights masterminded this two-storey addition, which holds a kitchen-dining-living area and master bedroom suite.

Photo: Richard Kiely

The extension features a striking glazed gable and two sets of bifold doors that make for a fabulous, light-filled interior. The original building’s stone facade has been carried through to the extension and paired with the oak for a seamless design.

Price Up Your Project

Looking for an indicative cost for your extension? The Build It Benchmark Report uses award-winning HBXL software for a quick and cost-effective way of pricing up your project.

Is your budget realistic?
Will there be money left over for your dream kitchen?
Amazing plans but no idea of cost?

If you are looking for a broad outline of your overall build costs before you decide which route to take, why not send us your plans and request a Benchmark Report? Find out more here.

8. Seamless Connection Created with Corner Bifold Doors

Looking to replace an old conservatory and create a large kitchen-diner, these homeowners built a brand-new steel frame extension.

The scheme includes Kloeber‘s aluminium bifold doors, which pull back from the corner to reveal a striking, cantilevered roof.

9. Contrasting Timber-Clad Extension

Studio Weave created this striking two-storey extension to a traditional stone cottage in Devon, which replaces a dilapidated and redundant garage building.

Photo: Jim Stephenson

The cubic design features a geometric timber-clad exterior and large swathes of glazing that provide uninterrupted views of the rolling countryside. Inside, the living spaces have a distinctive, natural feel.

Photo: Jim Stephenson

The clients specified organic building materials that call back to the home’s rural location and history – with a combination of Douglas fir plywood joinery, clay paint finishes and terracotta tiles.

10. Contemporary Zinc-Clad House Extension

Franklin Ellis Architects designed stunning modern side and rear additions to this brick-built detached house in Nottingham that successfully fuses old and new. The single-storey rear extension now houses a clean, modern open-plan kitchen/dining area. The space is flooded with ample light thanks to its open-corner glazed sliding door system and rooflights supplied by IQ Glass.

Essential Advice: Extending Your Home: The Ultimate Beginner’s Guide to Building a House Extension

Photo: Christopher Terry

The external red zinc cladding complements the existing brick, allowing a modern touch that remains sympathetic to the traditional style of the original building. The same red zinc continues on the metal roof of the two-storey side extension, where black Accoya timber cladding has been used to add to the variety of textures.

11. Innovative Glazed Kitchen-Diner Extension

The owners of this detached property overlooking the Surrey Hills approached Stylus Architects with a brief to maximise its views and foster a stronger connection with the garden. The result is an impressive rear extension that houses an open-plan kitchen-dining room, with a wow-factor roof that includes a partially glazed pitched section.

The vaulted ceiling above the new kitchen mimics the asymmetrical design of the original building and reaches a grand 5m in height. The gable has two distinct halves. The right-hand side has a full brick facade, while the steel structure remains exposed on the left.

12. Fantastic Indoor-Outdoor Connection

The owners of this property briefed Paul Archer Design to carry out a full house refurbishment that would support their growing family. The existing house already featured a tired side infill extension and a galley kitchen. The latter was knocked through to create one open-plan space to connect the kitchen, dining and living rooms.

Photo: Helen Cathcart

The glazing projects out beyond the rear facade to form a glass snug with minimal sightlines that helps create the sense of being outside while relaxing inside. A large pivot door leads out onto the patio from the kitchen to continue the strong connection to the garden and form an overall contemporary design.

More Essential Advice: Structural Options & Considerations For a Home Extension: Your Complete Guide

13. Contemporary Addition to a Stone Cottage

Tucked away in a quiet Norfolk village, this stone-clad cottage has been extended to create a stunning open-plan family space. IDSystems’ aluminium bifold doors were specified for their performance and to blur the line between indoors and outdoors.

14. Versatile Brick Addition

The modern rear extension to this Victorian terraced house in Camberwell is the work of Delve Architects. A palette of brick, pre-cast concrete and terrazzo tile form the basis of the design. A contrasting pale brick has been used both inside and outside the new addition, as well as along the boundary walls and down steps towards the patio, where they are laid in a basketweave bond.

Photo: Emanuelis Stasaitis

The architect also worked to maximise natural light, installing rooflights above the kitchen area. In the living area on the original ground floor, a pair of windows has been cleverly incorporated to bring in extra daylight.

15. Glazed Garden Room Extension

Rather than separating their new garden room from the main residence, the owners of this Category C listed property in Scotland instead decided to merge the two. The result is this single-storey glass box extension, designed by thatstudio. The new addition creates an open-plan space that provides a smoother connection between the original house and the south-facing rear garden.

Photo: Andrew Lee

The extension’s glazing is framed with a subtle grey quartz zinc cladding in keeping with the vernacular architecture in this conservation area setting. It provides a contemporary contrast with the characterful stone of the charming original building.

16. Curved Corner Extension

The front of this Edinburgh house features curved stone corners, which the architects Konishi Gaffney used as inspiration for this stylish contemporary side extension.

The unusual cladding was made with locally sourced oak, chosen for its ability to achieve a tight steam-bend radius of 1.5m. The oak planks, steaming and installation cost around £5,000 but add bags of character.

CLOSER LOOK Maximising your extension budget

Get your design fully costed at the planning stages, and lock down the full specification in an agreed contract. Avoid rough figures for things like lighting and instead map the details out before you get on site, so there are no surprises.
Focus your spending on the most visible, fixed architectural elements, such as the glazing and external claddings. You can always update light fittings and window dressings at a later date.
Where possible, use good-quality, off-the-shelf products (such as standard-size windows) to achieve a high-end look at an affordable price. Bespoke options can look fantastic, but be sparing in their use if you want to limit outgoings.
Specify traditional UK building methods and materials that small-scale builders can manage easily, rather than having to fork out for specialist installers. Blockwork is a familiar route for home extensions, for instance. Timber frame and modular options are also popular, and may prove to be a better bet if a guaranteed schedule and improved cost certainty are important.
Always ringfence a contingency of, say, 10% of your total budget – and only use it for unforeseen issues.
Vet your suppliers fully and double-check that everything you’re expecting is included in the price to avoid any hidden charges.
If you’re engaging individual trades, consider those with a smaller annual turnover who aren’t registered for VAT, so you can avoid the 20% tax on their labour.

Use Build It’s Estimating Service to get an accurate cost for your self build or extension project

17. Colourful Kitchen Extension

This extension project by Nimtim Architects to a terraced house in south London makes use of simple materials and bold finishes. The kitchen was made with standard carcasses and fitted with Formica-faced plywood doors, plinths and worktops in Hunter Green.

Photo: Megan Taylor

These features beautifully complement the exposed timber ceiling and yellow-painted wooden doors and windows, which make a wow-factor addition to this simple structure.

18. Creative Brick Addition

The owners of this London property approached Plot, a local architectural practice, to help extend and renovate their new home to open up the small, dark rooms and address its structural issues. The result is a unique design that still sits sympathetically in its surroundings.

Photo: Chris Snook

To the rear of the ground floor was a narrow outrigger kitchen and a separate dinng room. To address this, rather than build deeper into the garden space, the designers have added a side return extension. Inside, the rear ground floor layout has been transformed into an open-plan kitchen/living/dining area.

19. Listed Home Updated with an Efficient Glazed Link

This grade II listed house has been renovated and extended with a modern addition, connected via a new glass link. EcoHaus’ frameless windows and bespoke glass were specified to create the striking feature, allowing uninterrupted views out.

20. Victorian Home Upgraded with New Extension

Before buying their current house, Alex and Mireia Gregor-Smith had had no plans to move. They had extended and renovated their previous home, where their daughters Marina and Sofia were born, and were very happy with it.

But one day, friends, who lived around the corner, mentioned that a property just a few doors along from them might be coming on the market soon. The couple bought the home with plans to redesign the layout and expand the floorplan.

20. Victorian Home Upgraded with New Extension

Photo: Gilda Cevasco

After tackling various planning and construction obstacles, the couple finally finished the transformation, turning a Victorian property into a family home by reconfiguring the interior and adding a light-filled rear extension.

Expert Advice: Extension Design: Creating an Extension That Works With Your Home

21. Wow-Factor Two-Storey Extension

Paul Archer Design won the Build It Award for Best architect or designer for an extension project at the 2022 awards for Zucchi House, which included a double-height extension and an internal remodel.

The award-winning, wow-factor window design opens up the house to flow through the new extension, with the upper ground floor housing a new family kitchen-dinner with a dropped ceiling and circular rooflights.

22. Curved Glass Extension Design

Paul Archer Design masterminded this zinc-clad cylindrical glazed extension to a grade II listed home in Lancashire, which sits perfectly among its undulating rural surroundings.

Photo: Luke Hayes

The new addition provides expansive views over the countryside and adds an eye-catching feature to the period property, allowing it’s charm be brought into the 21st century.

23. Light-Filled Oak Frame Kitchen-Diner Extension

Jamie Adams and his wife Madeline chose to add an oak frame sunroom to expand their kitchen and dining space. Welsh Oak Frame created the wow-factor addition, which is complete with charming oak trusses and a striking glazed gable that looks out over the garden.

Photo: Luke Hayes

24. Victorian Home Transformed with a Colourful Redesign

Interior designer Alice Constable Maxwell unleashed her keen eye for colour on a dilapidated Victorian home, transforming it into the perfect family dwelling. The home has been upgraded with a dormer loft conversion and a light-filled rear kitchen-diner extension with colourful glazed features and a charming interior scheme.

Photo: Simon Maxwell

25. House Extension with Sleek Doors

Urban Front supplied the doors for this house extension and full renovation project in Surrey. The grand home features a set of six bespoke European oak entrances, including contemporary internal doors, a bifold garage door and a sleek front door.

26. Charming Country Home Upgraded with a Modern Addition

This historic home has been transformed thanks to a contemporary yet sensitive revision designed by Studio CHY. Set in a small village in the English countryside, the owners wished to replace the existing dilapidated extension to create a smoother transition through to the garden and take advantage of the stunning views.

Photo: Adam Carter

The architect’s aim was to contrast the historic fabric of the original house, while still enhancing its country charm. A historic archway has been reopened and lined in oak to create a dramatic new entrance that embraces the home’s period details.

27. Angular House Extension Clad in Charred Timber

This striking two-storey extension was designed by Neil Dusheiko Architects. Building at the rear of a terrace comes with site constraints, and for this project the roof line needed to be respectful to neighbouring properties.

home extension with timber-clad exterior and angular roofline

Photo: Tim Crocker

The striking house extension houses a light-filled kitchen-diner and living area. The glazed sliding doors create a seamless connection between the interiors and the patio area.

28. Seamless Side Return Home Extension

This large Victorian property had previously been refurbished on the upper floors but retained a cramped and uninspiring kitchen that wasn’t fit for the family.

The space was transformed by Hawksmoor Construction through an expanded full-length side return and rear extension, finished with pitched glazing and full-width doors from 1st Folding Sliding Doors.

kitchen-diner side return extension with full height and width glazing

Photo: Chris Snook

A classic herringbone wooden floor gives a timeless feel and, out in the garden, patio clay pavers are laid in the same pattern to provide a seamless transition.

29. House Extension with Contrasting Cladding

A house extension that contrasts the style of your existing property can transform its overall appearance. Using cladding to achieve this effect is a great solution, with so many options available that can be mixed and matched to create a wow-factor architectural finish.

Photo: Stale Eriksen

Oliver Leech Architects used a varied external material palette for this new two-storey addition. Handmade Danish grey clay tiles were chosen for the roof and upper storey, while Siberian larch clads the ground floor and around the dormer window.

30. Home Extension with Colourful Design Details

Colour doesn’t have to be limited to the furniture you decorate with or how you paint your walls. When it comes to the structural bones of a property, both internally and externally, many of us might not consider colour an option, but it’s a customisation that can make you feel like you’ve truly put your own stamp on your home.

Photo: Adam Scott

Here, Turner Architects has specified the patio door frames and bay window seat in a muted turquoise shade, adding a playful touch that makes the overall house extension pop. The rest of the architecture remains fairly neutral, with timber beams, a pale concrete kitchen floor and brick walls left exposed inside.

Words by Sander Tel & Georgina Crothers