There are three types of self build mortgage: advance stage payment (cost-based), arrears stage payment (value -based) and arrears stage payment (cost-based). With all of these, money is released in phases to allow you to pay your bills at key milestones. These are typically: buying the plot; foundations done; wall plate/frame erection; wind and watertight; first fix; second fix/completion. The amount paid out per stage is a percentage of either your actual costs or the value of the works, and is calculated based on your project’s individual requirements.