20 Extension Design Ideas

If you need to add space and there is room to add value to your home in the process (making sure you don’t exceed the ceiling value in the area) then an extension is the way to go.

Here are 20 ideas for great ways to add space to your home.

1. Reconfigure What’s There

As well as adding new space, reconfiguring the existing room arrangement to create the optimum layout for making the best use of natural light, views, access to the garden and drive, and to improve privacy, is crucial to making the new extension work.

Internal walls and doorways can be added or removed 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 – 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.

Use our Extension Cost Calculator

2. Consider Building Up

If you are looking to achieve maximum value for money with your extension, consider building over two storeys rather than just one, as the average cost per square metre (m²) is reduced by stretching the more expensive elements of roof and foundations over a larger area.

This cottage has been extended with a large two-storey addition and new veranda

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).

3. Contrasting or Sympathetic Extension?

When extending your home, choose either a contrasting but complementary style, or make the extension look like it has always been there. The former is much easier to pull off well.

If you decide to create a seamless extension, make sure you copy the key design elements, roof pitch, materials and details like the brick bond and even the mortar colour, or it will look wrong.

See our gallery of radical extensions that have been designed to stand out

4. Add a Sunroom

Smaller conservatories often don’t require planning permission, are excluded from the Building Regulations and are fairly inexpensive, 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.

A popular alternative is to build a sunroom — an extension with large areas of glazing, but with a conventional insulated roof and typically one insulated wall (particularly the one facing the boundary). The space can be open to the rest of the house, and the temperature can be controlled more easily.

5. Make Use of Ceiling Space

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.

This new extension features vaulted ceiling and reclaimed oak trusses

6. Link Separate Spaces with Glazing

When extending a period home, it can be difficult to find the right design to complement the existing property. One 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.

Using structural glazing it is possible for such a link to be constructed entirely from glass, reducing its visual impact and leaving 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.

Glazed walkways were used to connect a number of outbuildings to create this home

7. Create Outdoor Rooms

A covered outdoor living area provides somewhere to sit or eat outside during the warmer months, but is protected from either too much sunlight or light summer rainfall. This may take a traditional form such as a loggia or veranda, or be a more contemporary space, set beneath a projecting flat roof supported by slender steel posts, perhaps with an area of slatted sun louvres.


8. Choose Pocket Doors for the Best of Both Worlds

If you can’t decide between enclosing a new extension with a wall or going open plan, 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 pocket door can be slide back to create one large semi open plan space

Pocket door systems are available off the shelf (try Em-B) or you can buy the running gear separately (try Häfele) and have doors made up to suit your own design.

9. Maintain Privacy

Introducing lots of natural light is one of the key ingredients in successful extension design. Where a potential new window opening will look out onto a neighbour, the street, a side alley or directly onto a boundary, consider using obscured glazing, so you get the benefit of daylight but without anyone being able to look in or out.

Traditional options include textured or stained glass and glass blocks, and more contemporary options include acid-etched or sand-blasted glass and coloured glass.

10. Fireplaces: Bear Energy Efficiency in Mind

With increasing emphasis on energy efficiency, many people are blocking up open chimney flues and air vents or excluding them from their extension plans. Yet there are two energy-efficient options that still give the feature and comfort of real flames.

Flueless gas fires are 100% energy efficient and require no chimney or flue: a catalytic converter cleans all harmful combustion gases, producing just water and CO2. Designs include traditional fireplaces and stoves, and contemporary hole-in-the-wall models.

The second choice is a room-sealed woodburning stove, connected to an internal air source to prevent any draughts. They are highly energy efficient and there are some exciting modern design options.

Key Tips

  • If you can’t match a traditional home exactly, don’t try. A contemporary contrast is a more honest solution in this case.
  • It’s all about light. An extension will take away some of the light source to your original rooms, so make sure it is packed with glazing.
  • Create a feature. Whether it’s a staircase, fireplace, kitchen island or something else.

11. Add Feature Lighting

A well thought out lighting scheme will give your new space great atmosphere, allowing you to use different combinations of circuits for different activities. Independent control of each circuit using dimmer switches or smart switches with preset options is essential.

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.

12. Manage Noise

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 soft sound-absorbent materials into the room.

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.

Find out more about controlling noise in your home

13. Frame the Views from Your Extension

Position window openings to frame the best views and to improve privacy — by screening off any unsightly external features or neighbouring properties. Options include projecting bay windows and oriel windows set at an angle, with one or both reveals designed to act as a blinker.

This window seat artfully captures a view of nearby trees

Think about the shape of the window and the height of the cill, too — 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.

Window seats can be another useful device here.

14. Add a Contemporary Kitchen

If you are looking to create a contemporary designer kitchen in your extension but don’t have the budget for a bespoke design, create your own using modular units from suppliers like Howdens or the DIY sheds, combined with end panels, worktops and other features sourced elsewhere to recreate the same look.

Most trade suppliers do not offer panels large enough to create big islands or floor-to-ceiling banks of units to form an ‘appliance wall’, without obvious joints. You can overcome this by buying large sheets of MFC (melamine-faced chipboard) in a matching or complementary finish from a specialist such as Timbmet together with matching iron-on edging strips. Sliding metal timber unit doors to suit standard-size cupboard units are also available from CK Kitchens.

Take a look at 15 contemporary kitchens

15. Consider Extending into the Garden

Where the garden is large enough, an annexe might well prove a more sensible and manageable solution than extending the existing house. A garden building might provide additional games space, but would be much more exciting as self-sufficient accommodation, providing kitchen, bedroom and bathroom spaces.

16. Consider a Cantilevered Extension

Cantilevering is 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.

This award-winning cantilevered extension designed by Adam Knibb Architects is a clever solution to a challenging site

17. Make the Most of a New Staircase

If you decide to go for a new staircase when extending, consider making it a key design feature. Options include floating cantilevered treads, open treads, glass or metal balustrading, galleried landings, sweeping curves and spirals. It is probably the best opportunity to create an exciting architectural feature in the home.

See 21 statement staircases

18. Give Your Home 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.

This 1930s bungalow was also given an exterior facelift (and reclad in render) when it was extended

19. Embrace the Popularity of Oak

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.

Exposed rafters gives a more traditional country look in this extension designed by Roderick James Architects

20. Introduce Natural Light

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. In addition to bringing light deep into the floorplan of an extended home, these ideas will also help address issues regarding overlooking and privacy.

A roof lantern brings light flooding deep into this extended home

Is Your Project Insured?

Did you know that by starting an extension project, you could invalidate your existing home insurance policy?

Homebuilding & Renovating has partnered with leading insurance specialist Self Build Zone to provide bespoke solutions at market-leading rates.

Get a quote now to protect your extension project

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