Condominiums and spec homes are only residential construction projects if they have been purchased by the person owner who is going to occupy them live there before the beginning of construction.
In other words, if the owner of a lot hires a contractor to build a house but is not going to live there, then it is considered to be a commercial construction project. But if the owner of the lot will actually live in the house under construction, then it is considered to be a residential construction project.