The best house extension ideas will not only add the extra space required by the occupants of the property, but they should also enhance the existing spaces too.
If you are planning on building an extension, then it is essential that you do your research in order to get a firm idea of the kind of design that will work best for you. While talking to an architect and taking notice of similar projects in your area will really help when it comes to whittling down your choices, our round up of inspiration projects should also help.
From tiny extensions that have transformed the way the owners use their homes to stunning contemporary additions that have more than doubled the footprint of a house, we really do have it all.
1. Create a stunning glass link extension
Glass link extensions can be useful in so many different situations. In fact, a glass link is one of the best ways to approach a number of design challenges. They can be used to link a detached garage to the main house or an outbuilding or a barn to an existing property. Not only do they offer a way of connecting two separate elements, but they can also become useful extra living spaces in their own right.
"To get a glazed link extension right you need to consider how it will be installed," says architect Darren Bray, founder of Studio B.A.D Architects. "The best solutions are those that allow you to conceal the link’s supporting frame so that the glass appears to be the only thing present."
This project was originally made up of a cottage and a hay barn with a carport between. In order to unite the two buildings, a modern link extension with large frameless glazing was built to replace the carport.
2. Try to mirror elements of the existing building
While you may not be using matching materials for an extension, it always works well when elements, such as the form or roof pitch, of the existing property are in some way reflected within the new addition.
"We believe that contemporary architecture can sit happily alongside traditional and vernacular styles, but that a complementary relationship can be created through the use of materials and colour palettes," says Ian Phillips of VESP Architects.
Here, while the new two-storey extension that has been added to an old barn has been clad in zinc and red cedar for a decidedly contemporary look, the shape and proportions of the structure tie in well with the older building. Designed by Tim Offer Architects, the glazed gable remains private thanks to eye-catching timber shutters.
3. Consider overheating when designing a glazed house extension
If glass extension ideas are your thing, do consider how you will address the issue of overheating.
Design features such as overhangs and really thinking through the orientation of the new addition will help, as will treating the glass with a solar reflective coating.
The garden room extension here has been built using a steel frame and features solar reflective double glazing set into aluminium frames. A prefabricated skylight has been positioned into the centre of the new structure to bring even more light in.
4. Be adventurous with cladding ideas
Think outside the box when it comes to how you will finish your new extension off externally. There are many cladding alternatives out there that you may not have considered, from composites to porcelain tiles.
This small extension to a Victorian terrace property, designed by Richard John Andrews, was designed to look as though it slots in and fixes onto the existing house. Cork was chosen to clad the addition as it doesn't swell or get wet like natural wood and it repels water. Plus it is a natural insect repellent and adds an extra thermal layer.
5. Small house extensions can make a big difference
An addition doesn't have to be huge to completely change the way you can live in a house. Small house extension ideas can have a massive impact on the look, feel and layout of a property.
This Victorian semi-detached villa in Glasgow has been totally transformed by removing a small section of an old external wall and inserting an infill extension – designed by Ann Nisbet – measuring 1.85m wide into its place. Although the extension's footprint is just 2.95m2, it has made all the different internally thanks to the full-height dormer window which brings in plentiful light.
6. Don't assume a listed building spells playing it safe
Although some people can feel nervous about buying a listed building, there are many examples of stunning modern extensions that have been added to this kind of property. However, planning departments are often supportive of changes and alterations that respect the nature and fabric of the original building and working alongside a conservation officer will help.
This Grade-II listed farmhouse had been subject to a number of unsympathetic additions over the years and the owners went to Martin Hall of Hall + Bednarczyk for an extension design.
"Our fundamental approach was to ensure there was an honest distinction between the older sections of the house and the new," says Martin. "We designed the extension roof with a steep pitch, with slender verges that are reminiscent of the original tiles gables. We used a lightness of touch — we wanted to create a glassy echo of the original form of the building."
7. Reconfigure existing spaces when extending
When it comes to good house extension ideas, the existing space is often reconfigured to make the most of the new space. The reconfiguration will allow you to establish the optimum layout to make the most of access, views, natural light and privacy.
Knocking down internal walls and or moving doorways may be two ways to achieve the space you require and to integrate any new extension, to ensure you get real value and use from it.
Consider the position of the entrance and central hallway design – which should lead efficiently to all main rooms – and the relationship between key spaces, such as the proximity of the dining area to the kitchen.
8. A two-storey extension often makes more sense
Double-storey extensions are a great idea for those who are looking to achieve maximum value for money with their house extension, as the average cost per square metre (m²) is reduced by stretching the more expensive elements of roof and foundations over a larger area.
Here, a combination of a rear and wrap-around extension has given the owners the opportunity to reconfigure the entire layout of the house and has transformed the way they live in their home.
A two-storey extension is a great way to really change how your house looks from the outside too.
You could also build an extra storey over the top of an existing single-storey structure, such as a garage (providing the existing foundations and structure are adequate enough).
9. Carefully consider the materials you use for your house extension
When it comes to choosing materials for your extension you really need to decide whether you want to create a contrasting but complementary style, or make the extension look like it has always been there. The former tends to be much easier to pull off well.
If you decide on the latter, make sure you are matching materials and copy the key design elements, roof pitch and details like the brick bond and even the mortar colour, or your new addition will look wrong.
10. Site a new kitchen in a contemporary extension
One of the most popular reasons for building an extension is to create a bigger kitchen space and this is a great way to curate a new hub of the family home.
From small side returns on terrace houses to full-width rear extensions on semi-detached properties, the right kitchen extension ideas can offer the chance to rearrange a layout which doesn't quite work for your lifestyle and can give a tired home a new lease of life.
There are many different types of extension that work well for kitchens but one of the best ways to open up a dark and pokey galley kitchen is with a wrap-around extension.
11. Bring in the light with a conservatory or sunroom extension
Extension or conservatory? It is a common dilemma by those looking to add space. Adding a conservatory or sunroom is a great and often inexpensive way of increasing the footprint of a property.
Smaller conservatories often don’t require planning permission, may be excluded from the Building Regulations and are fairly cost-effective, making them one of the most popular home improvements.
A conservatory can have its drawbacks, however: it must be separated from the house by external doors to reduce energy loss, and it can be difficult to heat in winter and keep cool in summer.
Adding a sunroom is a popular alternative. They are an extension with large areas of glazing, but with a conventional insulated roof and insulated walls. The space can be open to the rest of the house, and the temperature can be controlled more easily.
12. Extend up as well as out
Tall ceilings can transform the way a room feels — larger rooms especially are made to feel even more spacious and impressive. An extension gives scope to add this feature for relatively little cost, either by digging down to lower the floor level, or by building up. In a two-storey extension this may result in a split-level on the first floor, which can add interest.
Where an extension is beneath a pitched roof, there may be the option to create a vaulted ceiling, open to the ridge. Instead of building a conventional flat ceiling with a void above, fit insulation within the pitched roof structure to create this feature.
13. Don't discount glazed links in period homes
When it comes to period homes, it can be especially difficult to find the right extension design to complement the existing property. One possible solution is to add the new space as an entirely separate building in a sympathetic style – either traditional or contemporary – and to join the two with a fully glazed walkway.
Choosing structural glazing for the walkway will reduce its visual impact and leave the original building’s character unaltered. This is a device favoured by many conservation officers and can work well in linking existing period buildings, too.
14. Turn your new house extension into a flexible space
When it comes to your house extension ideas, if you can’t decide between enclosing a new extension with a wall or going open plan with your layout, consider fitting sliding pocket doors, giving you the best of both worlds. When closed, sliding flush doors can give the appearance of a wall, but when open they can disappear within the wall, presenting a clear opening.
This is great for those wanted to create a multi-purpose room from their extension — perhaps one that can be used as living space for the majority of the time but as guest accommodation occasionally.
15. Use lighting to define new spaces and old
Your lighting design should not be overlooked when it comes to your extension. A well thought out lighting scheme will create a great atmosphere in your new space, allowing you to use different combinations of circuits for different activities.
As well as ambient lighting to provide basic background light for everyday activities, include accent lighting in the form of directional spotlights, uplights, downlights, wall washes, baffled (concealed source) lights, table lamps and standard lamps to create light and shade, which is key for atmosphere. Add decorative lamps, for instance, above a kitchen island or dining table as feature lighting.
Here, not only has an ‘up and over’ rooflight been used to flood the space with bright natural light, but channels in the walls and ceiling, fitted with LEDs, bring the extension to life as night falls.
16. Don't forget about changes in acoustics
Contemporary extensions with glass walls, polished stone or concrete floors and crisp, clean lines can look fantastic, but they can also create acoustic problems as sound reverberates from one solid flat surface to another. Such problems need to be overcome by introducing methods of soundproofing and noise control, such as by using soft sound-absorbent materials.
However, rugs, curtains and soft furniture are not always appropriate — in a dining or kitchen area, for instance. An alternative is to fit some form of acoustic panels. These can be fitted to the walls as textured profiled panels like wall art, or flat panels printed with any chosen image.
17. Be sure to maximise views when extending
Take the opportunity when extending to position window openings to frame the best views and to improve privacy — by screening off any unsightly external features or neighbouring properties.
Great options when it comes to window styles include projecting bay windows and oriel windows set at an angle, huge picture windows, swathes of sliding or bifold doors and even high level clerestory windows. Narrow elongated windows can create wonderful panoramic aspects, or be designed to frame a particular landscape view. Low-level windows can be effective at creating views when sitting or lying in bed.
18. Consider a cantilevered house extension
Cantilever extensions are a useful device for creating design features such as balconies, mezzanines or whole storeys that project out from the floor below and appear to float with no visible means of support.
"Cantilever design is defined as a structural feature that extends horizontally from a vertical element and is only supported by one end," explains Sabatino Torchitti, studio manager from Resi. "This can be as simple as a cantilever balcony or an open corner of a building. It’s also a popular design for recycled shipping container new builds, where one unit juts out from the top of the other."
19. Do consider staircase positioning when extending
Building an extension often involves a complete remodelling of the existing layout and it is often necessary to reconsider staircase design and location.
This extension project houses a stunning new kitchen which meant spaces elsewhere have been shifted around. The original cramped Victorian staircase within the house was removed and replaced with a new oak one in the kitchen extension — it features useful storage beneath too.
20. Give your entire house an exterior makeover
Instead of building an extension to match your property’s existing architectural style, the project can become part of an overall redesign scheme that completely transforms your home’s appearance. This is a good technique for adding character and value to buildings that are bland, utilitarian, unfashionable, or which have been extended unsympathetically in the past.
You might be able to undertake the remodelling work under Permitted Development rights (whereby planning permission is not required), but do check with your local planning authority first.
21. Expose oak beams for extra charm in a new extension
A vaulted ceiling with exposed oak beams makes a great design feature that gives a room instant character — ideal for a kitchen, sitting room or master bedroom. An entirely oak frame extension is ideally suited to a rustic-style property such as a cottage, farmhouse or a barn conversion, or an Arts & Crafts home.
A cost-effective option is to combine an oak frame principal roof structure (principal rafters, collar, tie beams, braces, ridge and purlins) with softwood rafters — the latter hidden behind plasterboard and insulation.
An oak frame extension can be encased within structural insulated panels (SIPs) or any other construction system to ensure it meets Building Regs’ standards of thermal efficiency.
22. Use plenty of glass to bring light into existing spaces
Bringing daylight into your extension from more than one direction to add multiple layers of light and shade, will greatly enhance the quality of space.
As well as maximising window and glazed door openings, consider introducing a bank of rooflights, a roof lantern or a clerestory (a row of windows set just below ceiling level and above the eye level) to bring in light from above.
This stunning single-storey extension, designed by SOUP Architects, has been clad in charred timber and was added to a listed granite barn dating from 1858.
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Michael is Homebuilding & Renovating's Director of Content, Vice Chair of the self build industry body, the National Custom and Self Build Association (NaCSBA), presenter of multiple property TV shows and author of Renovating for Profit (Ebury). He also runs an architectural and interior design practice, offering design and project management services. He is one of the country's leading property experts and has undertaken over 30 building projects including two self-builds and the renovation of a Grade-II listed farmhouse.
Michael has presented over 150 property shows for BBC, ITV1, Channel 5, UK TV Style, and Discovery RealTime, including I Own Britain's Best Home; Don't Move Improve; Trading Up; Good Bid, Good Buy; Build, Buy or Restore?; How to Build A House; and Hard Sell.
Michael is also a regular expert at the Homebuilding & Renovating Shows. He has written for leading British newspapers, including The Daily Telegraph, Sunday Times, Daily Express and The Independent and has appeared on news programmes such as BBC Breakfast.