A legal lot
The County says a parcel has to be legal to get a permit to build or grade. Outside the cities the County decides that from how and when the parcel was created, and a lot drawn on some old recorded maps can still show on the assessor's parcel maps, although recording that map did not by itself make it a legal lot. A certificate of compliance records that a parcel was legally created, but the County says it neither ensures that the parcel is buildable nor entitles the owner to a construction permit.
Water, and a septic system or a sewer
Water comes from a water provider or a well, and a provider's answer can decide whether a home can be built: in Cambria, the services district says the County requires its will-serve letter for any project on its water, and that it is not issuing new residential or commercial water or wastewater connections at this time, under an emergency declaration still in effect. A new well needs a County Environmental Health permit before it is drilled, and a well that serves a home has to meet the County health department's drinking water standards before a County building permit is finaled. Outside the cities and away from a sewer, the County requires a percolation test for a new septic system on an undeveloped lot, can conclude that a site cannot safely use one, and wants proof of a potable water supply before the septic permit is finaled.
Fire, flood and the Coastal Zone
CAL FIRE San Luis Obispo says the State Fire Marshal's fire hazard severity zones are used for setting construction rules for new buildings where wildlands meet communities, and for regulating development, including road dimensions, water availability and emergency signs. FEMA's Flood Map Service Center is the official public source for flood hazard information, and federal law can require flood insurance on a building in a special flood hazard area that secures a loan from a federally regulated lender; outside the cities, the County sets its own standards for building in a mapped flood hazard area. In the Coastal Zone, development can need a coastal development permit in addition to any other permit. Outside the cities the County can issue those permits, and the Coastal Commission has the final say on how the County's Local Coastal Program is read. The Commission says its digital map of the Coastal Zone boundary may not eliminate the need for a formal boundary determination.
A Williamson Act contract
California's Williamson Act lets a county or city and a landowner sign a contract restricting land to agricultural or related open space use, in return for a lower property tax assessment, and the Department of Conservation says the contract binds every later buyer. A notice of nonrenewal starts the nonrenewal period, and the land stays subject to the contract until it expires. The County calls the contract a legally binding, enforceable restriction, and its Williamson Act guide says land it designates Agriculture should be checked for one and that what zoning allows a contract may not. The County's rules for contracted land say each proposed home must be incidental to and in support of the agricultural enterprise on the property.
Your credit and the loan's purpose
Each lender sets its own rules on land. Federal guidelines for banks name the borrower's capacity to repay, creditworthiness and the value of the property among the credit factors a bank's lending should reflect. Whether the Loan Estimate, the Closing Disclosure and the ability-to-repay rule apply turns in part on the loan's purpose: Regulation Z does not apply to credit made primarily for a business, commercial or agricultural purpose, or to credit to a company. Its commentary lists factors for deciding whether a loan to buy something is for a business purpose, among them how closely the purchase relates to your work and your own statement of the loan's purpose.
