The problem with site built housing is of course that it has to exceed a certain minimum size in order to be profitable for the builder.   By contrast, manufactured housing,  because its is produced in the factory, is under no such constraint.   At the same time, manufactured runs about half the sq ft costs of site built.  By transitioning  from site built to offsite construction,  the BTR entrepreneur gains a twofold competitive advantage:  Homes can be kept to just the right size and at half the sq ft cost.