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23 Modern Extension Design Ideas

Alex and Sophie Nicholls have enlarged their traditional 1950s house with two contemporary box-shaped extensions designed to bring in the light
(Image credit: c/o AR Design Studio)

For those looking to improve, and not move, extending your property as part of an internal (and often external) remodel can offer the additional space you need and create a more attractive home.

When it comes to building an extension, a contemporary addition to the rear or side of your home is a popular choice. These examples are sure to offer plenty of design ideas and inspiration to get you started.

1. A Futuristic Design

Contemporary extension by Stan Bolt to existing home

(Image credit: Nigel Rigden)

Arts & Crafts meets futuristic fantasy with this modern addition and its wing-like roof from Stan Bolt Architect.

2. A Glass Box Extension

Glazed rear extension to Victorian house

(Image credit: Martin Gardner c/o AR Design Studio)

Frameless glazing sits alongside period brickwork in this stunning project designed by Hampshire-based practice AR Design Studio.

3. A Victorian Home Extended

Two extensions added to Victorian house

(Image credit: Jeremy Phillips)

Two modern ground floor box-out extensions, designed by architect and homeowner Nils Feldmann, have increased the living space in this Victorian home, and contrast against the existing brickwork.

4. A 1930s Home Extended

This 1930s semi detached house has been transformed by its owners into a bright and happy family home — all for just £40,000

(Image credit: Clive Doyle)

A modest rear extension to this 1930s semi-detached home offers the extra space the growing family needed, while keeping within a tight budget.

5. A Cantilevered Addition

A pairing of a dramatic cantilevered extension and stone barn brings a vibrant feel to Paul and Elaine Haffey’s new home

(Image credit: Chris Hill)

A dynamic new cantilevered extension connects with this original stone barn, forming an angular and quirky stepped layout inside and providing a spectacular master bedroom space.

6. A Flat Roof Extension

Two extensions have transformed Sue and Terry Austin’s Hampshire house into a comfortable modern home

(Image credit: c/o AR Design Studio, Martin Gardner)

A flat roof rear extension designed by AR Design Studio houses a large kitchen diner and opens up the ground floor of this Hampshire home. A second two-storey side extension, clad in the same London stock brick as the existing property, houses a utility at ground level and a new master suite above.

7. A Series of Contemporary Bolt-Ons

Farmhouse With Contemporary Extensions

(Image credit: David Barbour)

A collection of contemporary extensions designed by Paper Igloo, clad in timber and Cor-ten steel and connected by glazed links, has been added to an old farmhouse.

8. A Bungalow Transformed

A 1970s bungalow has been transformed in to a modern, open plan home with a contemporary remodel and extension

(Image credit: Jeremy Phillips)

A far cry from the existing dated red-brick bungalow, the homeowners here added a single-storey extension and internal and external remodel to create a California-style home.

9. A True Wrap-Around Concept

two-storey extension with glass façade wraps around this listed water tower

(Image credit: Jeremy Phillips)

Thanks to the vision of Ellis Williams Architects, a convex two-storey extension with glass façade wraps around this listed water tower.

10. A Box-Out Addition

timber frame extension to bungalow

(Image credit: Simon Maxwell)

From bungalow to brilliant — this timber frame first floor addition with contrasting cladding boasts wow-factor.

11. A Timber Triumph

Extension to Historic Home

(Image credit: Alistair Nicholls)

Designed by Beam Cottage Architect, a new glazed link offers a transition between this period cottage and its modern rear, complete with a dramatic timber first floor box.

12. From Chalet Bungalow to Chalet Style

Remodel and extension of bungalow

(Image credit: Paul Arthur)

A dramatic first floor extension, complete with covered balcony has turned this bungalow into a chalet-style home that wouldn’t look out of place in a luxury ski resort.

13. A Basement Extension

Extension for Victorian Basement

(Image credit: Simon Maxwell)

A stylish basement extension designed by Riach Architects offers open plan family space to a Victorian terrace in Oxford.

14. A Steel-Clad Extension

A striking Cor-ten steel-clad extension to a granite steading in Aberdeenshire offers open plan living to its owners

(Image credit: David Barbour)

This double-height Cor-ten steel-clad wedge by Andrew McAvoy of Retool Architecture offers striking contrast to a granite steading.

15. A New Bedroom Corridor

Single-storey extension to house

(Image credit: Simon Maxwell)

A post-war property has been expanded thanks to a unique timber-clad corridor of bedrooms designed by Dan Brill Architects.

16. A Two-Storey Addition

A dated bungalow has been transformed with a modernist-inspired renovation and extension

(Image credit: Darren Chung)

A boring bungalow becomes a Modernist masterpiece thanks to a two storey additio by Matt Maisuria Architects.

17. A Farmhouse Extended

Wayne and Lorrie Bilsborrow have transformed their granite farmhouse with the addition of a contemporary timber extension

(Image credit: Nigel Rigden)

A larch and stainless steel wing by Room Architects offers a dynamic contrast to this period farmhouse — and proof of just how these older agricultural buildings can be transformed.

18. A Glass Basement Addition

A listed London home has been extended in glass, creating a contemporary living area above a new basement studio

(Image credit: Simon Maxwell)

This glazed box designed by Belsize Architects proves that extensions do not have to be huge to make a visual impact.

19. A Glazed Side Extension

Light-filled Extension to a Victorian Home

(Image credit: Simon Maxwell)

Shards of glass lend to the futuristic feel of this flat-roof addition to a Victorian home, designed by Coffey Architects.

20. A Timber Box Extension

A 1970s home on a Hampshire cul-de-sac has been transformed into a modern, eco-friendly timber clad home.

(Image credit: Nigel Rigden)

A new timber frame box linked via glazed panels from PAD Studio renders this 1970s home unrecognisable.

21. A Multi-Storey Tower

A stunning and unique contemporary extension to a listed Victorian home in East London

(Image credit: Nigel Rigden)

Adding interest, this multistorey timber tower rear designed by 51% Studios sits above a new light-filled base, offering increased accommodation.

22. A Jagged Addition

Alex and Sophie Nicholls have enlarged their traditional 1950s house with two contemporary box-shaped extensions designed to bring in the light

(Image credit: c/o AR Design Studio)

A series of jagged boxes set off from one another – one grey rendered, one timber clad – offers a splash of modern style, designed by AR Design Studio.

A modern glass addition to their cottage has enabled Adrian and Amy Mole to convert and incorporate outbuildings to create one characterful, unique home

(Image credit: Alistair Nicholls)

This functional, frameless glazed link by Emrys Architects connects three buildings to form one home.

Daisy was Features Editor on Homebuilding & Renovating for more than five years and had a passion for all things design. She has since moved on to pastures new.