ADUs are an affordable type of home to construct because home owners do not need to buy extra land to build them as they already own it. Additionally,  there is no need for major new infrastructure, structured parking, or elevators. ADUs can provide a source of income for homeowners. ADUs are built with cost-effective wood frame construction or SIPs (structural insulated panels) , which is significantly less costly than homes in new multifamily infill buildings. ADUs allow extended families to be near one another while maintaining privacy.