It depends to some extent on the height of the walls and the number of features and projections involved but for budget purposes, you can work on £25 to £30 per m².

You may find mortgage lenders more flexible than you think – it’s certainly worth sounding out a few different companies that specialise in self-build mortgages or bridging loans for renovation (see page 193 for Build It’s regular guide to self-build mortgages) to see what advice they have. If you still have no luck, one unorthodox way forward would be to talk to the vendor of the house and put your cards on the table. Offer to buy the property for say, £260,000 (£40,000 more than the asking price) provided you could delay the payments. This would reduce the profit on the project but both parties would benefit by such an arrangement. If the vendor agrees, you would need to involve a solicitor to protect your interests in what would be an unusual way of way of buying a property.