People tend to forget the incidentals that must also be paid for when taking on the role of a building contractor or property developer. Things like: insurance- public liability and employer's liability, tool and plant hire, contingency sum (for unseens), licences and other fees (for hoarding, utility connections, permits etc), waste disposal costs, security etc. Even on an apparently small or straightforward build you need to consider all these. I'ts unlikely that the capital appreciation available on one small project would be sufficient to attract or warrant the input of two or more investors/ partners in the whole process. Most builders, even the smallest operation, would have quite a lot of money tied up in plant, tools and machinery- all of which are essential to getting work done efficiently and economically. As the saying goes: "if it was easy everyone would be doing it".