The cost of a London side extension will depend upon several key aspects of the extension including the area that the extension will cover, the type of material the extension will be principally made up from, the method chosen to construct and cover the extension roof, the type and size of the extension doors and rooflights and the extent to which structural work will be needed to the new extension and existing house. Secondary factors such as if the extension will include a kitchen, the extent and type of lighting, the type of flooring chosen and the method of heating will also have an impact on the cost.

The cost of a small side extension (less than 10m2) – £40,000-£55,000

With a 2m bifolding door and 3 Velux rooflights, London Stock brick a GRP roof or felt roof, electrics, small external patio area and central heating from an existing boiler into 2 radiators.

Other possible costs include: Building control: £400, Architect fees: £800, Party Wall agreements: £500 per neighbour

This type of extension is widely used in London and it hugely improves the slightly dark and cramped kitchen area of Georgian and Victorian houses found in London. This budget would allow the incorporation of very good quality doors, rooflights and the use of London Stock brick. This budget would also allow for some creative use of the elements to create a really special extension.

The cost of a medium side extension (around 15m2) – £55,000-£75,000

With a 4m bifolding door and 3-4 large Velux rooflights, London Stock brick a GRP roof or felt roof, electrics, external patio area and central heating from an existing boiler into 2 radiators.

Other possible costs include: Building control: £400, Architect fees: £1,000, Party Wall agreements: £500 per neighbour

This budget would allow the incorporation of very good quality large doors opening onto a large patio area, rooflights and the use of London Stock brick. This budget would also allow for some creative use of the elements to create a really special extension. The price would increase to the higher end given with the addition of elements such as a kitchen, new boiler, underfloor heating, low profile doors and windows, a larger landscaped area outside the doors, retaining walls around the patio, specialist lighting and so on.

The cost of a large side extension (around 20m2) – £75,000-£100,000

With a 5m bifolding door and 4 large Velux rooflights, London Stock brick a GRP roof, electrics, external patio area and central heating from an existing boiler into 2 radiators.

Other possible costs include: Building control: £500, Architect fees: £1,500, Party Wall agreements: £500 per neighbour

This budget would allow for some creative use of the elements to develop a  a unique extension, designed to complement the space it occupies. The budget would allow the incorporation of very good quality large doors opening onto a large patio area, rooflights and the use of London Stock brick. The price would increae to the higher end with the addition of elements such as a kitchen, new boiler, underfloor heating, low profile doors and windows, a larger landscaped area outside the doors, outside lighting and electrics, retaining walls around the patio, specialist internal lighting and so on.

The cost of a large side extension with specialist elements such as a cantilevered roof, all around low profile glazing, lead or sedum roofing, underfloor heating (around 20m2) – £100,000-£180,000

With a 8m low profile, extra high sliding doors and 2-4 very large custom made electric rooflights, lead, sedum or GRP roof, internal electrics, specialist underfloor heating, external patio area with decorative retaining wall, external lighting and electrics.

Other possible costs include: Building control: £600, Architect fees: £2,500, Party Wall agreements: £500 per neighbour

This budget would allow for extensive creative use of the elements to create a unique extension. The budget would allow for careful planning by an architect to ensure all the elements fit together in an aesthetically pleasing way. The design could include the incorporation of very good quality large doors opening onto a large patio area, rooflights and the use of London Stock brick. The price would increase to the higher end given with the addition of elements such as a bespoke or designer kitchen, new boiler, underfloor heating, low profile doors and windows, a larger landscaped area outside the doors, outside lighting and electrics, decorative retaining walls around the patio, solid stone steps into the garden, specialist internal lighting and so on.

What to do next?

See our page of London side extensions for some pictures of recent work.

You may find our London side extension FAQs helpful.

If you are planning an extension and want to talk through your plans contact us.

 

 

 

 

Leave a Reply