Postby sw18er » Tue Aug 01, 2017 11:27 am
It's really difficult to get precise numbers on budgets before starting a project. No matter how carefully you scope it out, you'll almost certainly find your estimates are too low. The old joke about building work generally costing double your first estimate has some truth.
Things get discovered once the demolition/strip out starts, you will almost certainly change your mind on plans during the work, and all the large items like sash windows, glass doors, kitchens, bathrooms, flooring, lighting have a tendency of costing more than you ever expected.
To get a feel of project costs, check out some of the local building companies on Houzz - lots of them list a rough project value, albeit these still often exclude things like professional fees, furnishings, fittings etc.
You will save money by using small building teams, paying in cash, not making changes once the work starts, doing the project management yourself, working hard to source materials cheaply, and living in the house while the work is done.
Roughly speaking £75-100/sq ft will get you a functional finish assuming no major structural works. £200/sq ft if you want something impressive, and £300/sq ft if you want something with high-end custom joinery, lots of glazing, expensive kitchens and bathrooms, clever lighting, new plumbing, all the gadgets etc. Aiming for a top end finish will get you an amazing house, but the re-sale market in Clapham/Balham/Wandsworth tends to be reluctant to pay a premium for this - albeit with a 4000 sq ft house you might get lucky given the nature of the buyers ... just remember these size of houses can be really illiquid assets, so be careful if you plan on selling in 3-4 years.
With builders - you will get a wide range of prices - my experience is you pretty much get what you pay for here. The companies with good, long standing reputations will take a higher margin, but you get a better finish, and probably less problems further down the line.