Lenders may make shared appreciation loans pursuant to this chapter for the purchase of real property improved with one- to four-dwelling units, including structures ancillary to such dwelling units and including attached single-family dwelling units, single-family mobilehome units placed upon permanent foundations, residential condominium units, and dwelling units within a planned unit development. Shared appreciation loans shall be made to finance only owner-occupied dwelling units, but in the case of two- to four-unit dwellings financed under this chapter only one of the

units need be owner-occupied. A dwelling unit shall be conclusively deemed to be owner-occupied for purposes of this chapter if an original recipient of the shared appreciation loan certifies in writing to the lender at the time the loan is made that he or she will occupy the property.