It would appear that it does apply. Reg B 202.5(a)covers applications for credit involving a lien on a dwelling - .5(c) defines residential structure 1-4 family. The real answer I think is the Staff Commentary in 202.5(a(1) includes a business purpose in the requirement to provide a copy of the appraisal.
That is my opinion - I would be interested in other's viewpoints.
Allan D. Virr, CRCM,CRP
Compliance Audit Solutions, LLC