Zoning laws govern how many homes are allowed on a property. These laws vary by city, county and other forms of local government, notes Lawyers.com. For example, in rural Sonoma County, California, only one house is allowed per 10 acres of land under the density limits of the county's general zoning plan, according to the county Permit and Resource Management Department.
In most zoning areas, Sonoma County allows second units and guest units that create greater density than generally permitted by the zoning plan. Second units are limited to 840 square feet, while guest units are limited to 640 square feet and cannot include a kitchen, notes the Permit and Resource Management Department. Further restrictions whether a second unit is allowed include minimum property sizes if the second unit is provided with water and sewage.
Fairfax County in Virginia provides another example of zoning laws pertinent to building two homes on one property. The county's zoning ordinance generally allows only one house per lot, regardless of the size of the lot, according to the county. Limited exceptions exist to this rule but even when a second unit is allowed, use restrictions exist, such as limitations on they number of people that can live in the second unit.
Generally, zoning provisions that influence whether a second home on a property include density and minimum lot size regulations, as well as restrictions on what part of a property can be built on, according to Lawyers.com.