In the US, I know there is a sort of convertible building loan - you need to present the bank with a plan for something that will in short order be a house that

In the US, I know there is a sort of convertible building loan - you need to present the bank with a plan for something that will in short order be a house that can secure a mortgage. Once the house is complete with a CoO, it turns into a mortgage. I'm guessing the loan underwriters will be uncomfortable with the risk profile of a decade long project of self improvement, but what do I know?