Extensions

by Hannah Fenton

October 20, 2017

On-screen inspired London terrace basement extension

Film executive Niels Swinkels and his wife Erica took inspiration from on-screen interiors to turn their London terrace into a bright, open home. When film…

Paying for your self build differs from the traditional method. Find out how much you can expect your self build to cost.

self build guide how to pay for your self build

Image: Cotswold Architects (01285 238 528; cotswoldarchitects.com)

 

How to work out your budget

There is no such thing as an average self build cost, because issues such as ground conditions, access to the site, location and proximity of services all have an impact on the expenditure. BuildStore (0345 223 4888; buildstore. co.uk) has a handy calculator on its website that will give you an idea of the total cost of your self build, plus a breakdown of sums required for kitchen, bathrooms, renewable energy and services.

If you want to build an extension, a number of useful websites offer cost calculators based on your current home, location and the type of extension (try moneywise.co.uk and moneysavingexpert.com). As a rule of thumb, expect to pay around £1,200 to £1,500 per sqm for a single-storey addition and add an extra 50 per cent for a two-storey project.

 

Sticking to what you can afford

Work out accurate calculations and you’re on the way to building your dream home. A contingency of 10 to 20 per cent will act as a cushion against any unexpected costs. A 10 per cent contingency is generally recommended for a flat site where the ground conditions are known, and 20 per cent for a sloping plot or one where you’re not sure what may lie beneath the surface. A very rough guide is that one degree of incline costs an extra £1,000, so a 45° slope may give you fantastic views and easier drainage, but could mean an extra £45,000 in groundworks. The exact amount your self build will cost depends on a number of factors, including ground stability, the height of the water table and whether the spoil has to be taken to land fill.

It’s essential that your builder fully understands exactly what you want from the outset, which is where an architect’s technical drawing is key. This allows the builder to assess the cost of materials – bricks, tiles, windows, stairs, doors, beams, lighting, sanitaryware, flooring – and come up with an accurate  figure. It will reduce the chance of any nasty surprises, such as cost inflation or disappointment with the final result. ‘Experience in the kind of work you’re looking to have done is absolutely vital, but it’s worth remembering that experience relies a lot on the quality of the builder’s colleagues,’ says Brian Berry, chief executive at the Federation of Master Builders (0330 333 7777; fmb.org.uk). ‘A builder will be working with their own team and possibly subcontractors as well, so you’re relying on their ability to pick the right people for the job. Good builders will have a solid mind for numbers, be excellent at managing people and, vitally, should be adept problem solvers.’

 

Self build cost saving tips:

  • Source materials through your builder as you’ll benefit from trade accounts and it’s usually the most cost-effective method.

  • If you are managing your own build, don’t be afraid to ask suppliers for trade discounts.

  • If you have some flexibility, try one of the websites that aim to keep unused building materials out of skips, such as recipro-uk.com, builders-surplus.co.uk and buildtrade.co.uk – they all list available stock online.

  • For £75 you can get reliable estimates for building services based on your drawings at estimators-online.com.

  • Reuse and reclaim as much as you can when clearing the site, as this saves on skip hire.

 

Words: Amanda Cochrane; Jo Messenger, Photography: Matt Clayton; Logan Mcdougall-pope; Emma Stewart photography, Graph and Fictures: Buildstore

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