Party Wall Survey

Advice from expert party wall surveyors – London loft conversion or extension?


Things are a bit different if you live in a rural area. But life in London during lockdown has proved difficult for many people. Staying home in a space that isn’t quite big enough has left thousands of us feeling restricted, frustrated, and desperate for more space.

At the same time, the virus is making selling a home difficult in many ways, and people are beginning to think creatively. Instead of selling up and moving somewhere bigger, would you consider a room in the roof or a garden extension? If so, which is best?

As experienced party wall surveyors, London based so familiar with the capital’s many housing challenges, we thought it was worth looking into. Here are some tips to help you make the decision whether to extend or not and if so, how.

22 common sense tips for deciding on a loft conversion or garden extension

  1. A loft conversion is a great idea if you either want another bedroom, home office or home school
  2. In general, a loft extension gives you at least one extra room
  3. Extending into the garden delivers extra living space that can also be used as a home office or home schooling space
  4. As a rule, the extra space you get from an extension isn’t as big as you get from extending into the roof
  5. Whatever your extension plans extending means you avoid the costs of moving, including Stamp Duty
  6. Did you know that adding loads of extra bedrooms to a property with limited living space isn’t a wise idea? Demand will be limited for a home that’s not properly balanced. The same goes for gardens – if you extend so much that your garden ends up smaller than everyone else’s in your road, it can push the eventual selling price of your place down
  7. Extending either way is disruptive, with loft conversions a bit less so than garden extensions
  8. Consider if it’s worth the hassle – a garden extension might mean you need to move out for a few months while the work takes place
  9. Trees are tricky. Many trees are protected by Tree Preservation Orders, so make sure you take trees into account when asking for planning permission
  10. The average cost per square metre for an extension outside London in 2020 was £1,200-£1,500. In London and the South East, it’s more like £1,500-£2,000, maybe even more. For two-storey extensions add 50% to the cost of a single-storey one. An extra bathroom or kitchen will cost you £5,000-£10,000 more (source:
  11. Research from Nationwide reveals how an extra double bedroom and en-suite on a three bed home, whether via a loft extension or garden extension, boosts the value by over 20%. With the UK average house price at £245,000 that’s an extra £49,000. Is that enough to cover the extension you want to build?
  12. Has anyone else in the area extended their home in the same way you want to? If so, and they sold it, how did the extension affect the property’s value?
  13. Check your local authority planning rules to see if the project falls under ‘permitted development’
  14. If any of the work is structural – which is probably will be – the UK’s building regulations say you’ll need planning permission
  15. If the work affects a shared wall, you’ll need a party wall agreement – which means you need an experienced party wall surveyor, London based with all the right insight into the area you live
  16. Always get at least three quotes for the work to be sure you’re getting a good deal
  17. Ideally use a builder who has been recommended to you, a builder who is happy to refer you to previous clients for feedback
  18. It sounds obvious, but you need to make sure up front that you’ve got the money to pay for the work!
  19. Don’t pay the builder all the money up front. Work out a payment structure that gives them money to spend on materials and wages when required. This also means you’ve got funds held back in case things go wrong and you end up in a dispute
  20. Find a good local RICS surveyor who can let you know how much the value of your home will increase – it might be less than you imagine
  21. Hire an architect who has with good local knowledge and has experience of similar builds
  22. Bear in mind, thanks to Covid, that the project could be delayed – planning consent can take as long as three months, sometimes longer

Contact us for London party wall surveys and much more

Having an experienced trusted RICS surveyor on hand can make all the difference between the home extension project from hell and a smooth-running experience that doesn’t disrupt your life and peace of mind too much. Can we help you decide how to proceed with your home extension plans?