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15 Rear Extension Design Ideas

Modern CLT extension to listed barn
(Image credit: James Morris)

If you’re looking to add value as well as extra space to your home, then a rear extension may be the project for you.

If you are carrying out your work under Permitted Development, you will be expected to build in the same material as the existing dwelling. This must be done carefully, perhaps requiring you to source reclaimed materials to get a good match, or tint the bricks for a seamless look.

Alternatively, you could design an addition in a contrasting style. This makes a statement and can be easier to achieve success with than trying to match old and new.

Here, we take a look at some of the finest examples of rear extensions in recent times.

(MORE: Need a quote for your own extension project?)

Do I Need Planning Permission for a Rear Extension?

If your home is not in a conservation area or restricted by Listed Building consent, you may find your rear extension falls under Permitted Development.

This means that you can extend up to 8m from the original rear wall of your property on a detached home, or up to 6m on a semi detached or terraced home. In either case, your extension must not be higher than 4m. There are further restrictions if your project is to sit within 2m of a boundary (in this case the eaves must not be higher than 3m).

These measurements apply to single-storey extensions only, but some two-storey additions are allowed too.

1. A Striking Clad Extension

Modern extension to house

(Image credit: c/o AR Design Studio)

This grey rendered blockwork ground floor extension supports a timber frame bedroom ‘box’ above.

  • Build cost: £175,000
  • Location: Hampshire

2. A Sensitive Extension

Contemporary kitchen extension to listed cottage

(Image credit: Andy Spain/Charlotte Wood)

A contemporary-style addition clad in western red cedar contrasts with this original Grade II-listed cottage.

  • Build cost: £175,000
  • Location: Hampshire

3. An Extended and Renovated Cottage

Cottage extended to bring in light

(Image credit: Andrew Lee)

A new glazed space to a traditional whitehouse croft, provides a kitchen and utility room filled with natural light.

  • Build cost: undisclosed
  • Location: Isle of Skye

4. A Modernist Addition

Modernist extension to converted mill

(Image credit: Jeremy Phillips)

A cantilevered timber-clad roof appears to float on clerestory windows set above a white rendered wall on one side, and sliding doors on the other.

  • Build cost: undisclosed
  • Location: Denbighshire

(MORE: Thinking about a single storey extension? Here’s what you need to consider)

5. A Listed Stone Cottage Extension

Stone extension to listed stone cottage

(Image credit: Nicholas Yarsley)

The sympathetic oak frame addition, with reclaimed triple Roman clay tile roof, offers a family sunroom.

  • Build cost: undisclosed
  • Location: Bath

6. An Extended Farmhouse

Contemporary extensions to farmhouse

(Image credit: David Barbour)

Two new structures, clad in timber and Cor-ten steel, are linked to this old farm building with a glazed corridor.

  • Build cost: £355,800
  • Location: Inverness-shire

7. An Extended 1950s Home

Remodel and extension to 1950s home

(Image credit: Simon Denison)

This large rear addition incorporates a spacious kitchen diner and separate open plan living room, which open on to a patio.

  • Build cost: undisclosed
  • Location: Cardiff

8. A Glazed Kitchen Addition

Glazed rear extension

(Image credit: Paul Arthur)

This single-storey kitchen extension opens onto the garden with powder-coated bifold doors from Origin.

  • Build cost: £120,000
  • Location: West Midlands

9. A Zinc-Clad Rear Extension

Flat extension clad in zinc

(Image credit: Simon Maxwell)

This rear single-storey addition to a London flat in a conservation area has been clad in a pre-coloured dark zinc.

  • Build cost: £240,000
  • Location: North-west London

10. A Frameless Glass Extension

Glazed rear extension to Victorian house

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

Using contemporary frameless glass, a new bright open plan kitchen/dining/living space has created, which opens on to the rear garden without impacting on the traditional brick shell of the building.

  • Build cost: £400,000
  • Location: Hampshire

11. A Dramatic Remodel

Remodel and extension of bungalow

(Image credit: Paul Arthur)

This 1930s dormer bungalow has been transformed into a stunning chalet-style home thanks to a series of rear and side additions.

  • Build cost: £150,000
  • Location: Worcestershire

(MORE: If you’re thinking about adding a two storey extension, make sure you read this first)

12. A 1950s Home Extended

Contemporary extension to 1950s home

(Image credit: Jody Stewart)

This 1950s home has been opened up thanks to a rear extension which houses a new kitchen diner that connects with the garden through bifold doors. The addition has been clad in white render to contrast against the existing brick building.

  • Build cost: £95,000
  • Location: Bedfordshire

13. A Budget Addition

Rear extension to semi detached house

(Image credit: Clive Doyle)

Thanks to a new kitchen extension, this formerly cramped 1930s semi-detached home now offers the family with much-needed additional space. The crisp white render and modern glazed openings create a clear distinction between old and new.

  • Build cost: £40,000
  • Location: Nottingham

14. A Cantilevered Wing

Cantilevered extension to barn conversion

(Image credit: Chris Hill)

As part of the conversion of the stone barn on site, a dramatic cantilevered timber-clad bedroom wing extension has also been added to create the space the homeowners need and create a clear separation between living and sleeping quarters.

  • Build cost: £350,000
  • Location: Northern Ireland

15. An Extended Barn Conversion

Modern CLT extension to listed barn

(Image credit: James Morris)

Built of and clad in CLT (cross-laminated timber) with frameless glazed openings, this lateral extension spans the rear of the site, consequently reorientating the outlook of the existing Grade II-listed barn, to make the most of the garden views.

  • Build cost: £250,000
  • Location: Hampshire

(MORE: Want an extension that breaks the mould? Check out these radical designs)

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