Assuming the loan is made to the property owners (and not the builder), you have a plain vanilla extension of credit to consumers for a personal, family, or household purpose. All of Reg. Z will apply. Based on what you described, Appendix D should be able to generate the transaction disclosures. You will be taking a lien on the consumers' principal dwelling and this is not a RMT, so ROR will apply.
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...gone fishing.