View All Services

Free Guide


A guide to design and build a Dream
House Extension

Can’t find what you’re looking for? We are here to help!
Ask Monica a question! She really works here!

Ready to work with the best builders?

Call us today to find out more, and we’ll be happy to provide you with a free and friendly quote for your house extension anywhere in London.

The cost of a London Home Extension will vary greatly between £ 20,000 and £ 70,000 depending on the type of property you own and your requirements. While there is no precise formula for obtaining an accurate cost for your extension , we have worked out an indicative price guide for building extensions in London).

A typical ground floor extension may bear a cost of around £ 30,000 - £ 50,000.

The price will vary depending on several factors such as location of the house; ground conditions; quality of finishing; electrical and plumbing work; kitchen and bathroom fittings, and the type of extension required.

One-storey extensions are more common, however two-storey extensions can create additional space without going into the loft. Adding a two-storey extension doesn’t mean that it will cost you twice as much. Just multiply the figure for a single storey by two, and deduct 20% to get a rough idea of the cost.

The most common size of extension is 15 to 25 square meters, which can have construction costs between £20,000 and £35,000 (excluding the interior fitting). The cost for interior fitting can range from £10,000 to £20,000 for a small single-storey extension.

General House Extension Costs for London

Planning Costs

£ 1,000 - 3,500

Single Storey

£ 20,00 – 65,000

Double Storey

£ 20,000- 115,000

Shell build cost (windows, external doors, roof etc.)     

£ 600 per m2

Fixture & Fittings (electrical, plumbing, plastering, flooring)      

£ 400 per m2

Decoration Finishing

£ 10-15 per m2


The given costs will be more variable depending on the preferences of the homeowner, for example stone flooring is cheaper than timber.
Materials used for popular glass extension range from self-cleaned glass, fire resistant glass or glass that filters the sun. Flat roofs are cheaper to build than pitched designs.
Labour in highly urbanized area is different than rural areas. Additional cost might be added to materials that are imported or higher quality.

Construction cost might fluctuate due to economic conditions and availability of the contractors and materials.
It is always advisable to add from 10% to 15% more on top of the estimated cost to cover for the price fluctuation.

Living in a house that you and your family seem to have outgrown can be tough. Always having to move something to get to something else; constantly losing things; tolerating a house that looks a mess even when you’ve just tidied it… if these things sound familiar, you’ve to two choices on your hands: Move or improve.

According to research by the University of Cambridge, British homes are among the smallest in Europe. They discovered that between 25 and 30 per cent of homeowners are dissatisfied with the amount of space they have available, so you’re not alone in feeling the burden of your cramped conditions.

But rather than give up on their family homes and move to new communities, record numbers of people in Britain are choosing to stay put and invest in their homes to make them more suited to their needs. If you’re thinking about a house extension in London to add more space to your home, talk to Simply London Builders today for expert help and advice.


If you get a cheaper quote for the same work, and WE WILL DO OUR BEST TO BEAT IT !

We’ve worked hard over the years to strike a great balance between quality and value.

We may not be the cheapest builders in town for every job, but you can bet we’ll outperform them on the quality of our work.


Our Clients Include:

  • Property Developers
  • Private House Owners
  • Estate Agents
  • Residential & Commercial Property Maintenance Companies

Simply London Builders

Gas Safety Logo

Free consultation No pressure or obligation