Plus1House has been created as a public service by the American Institute of Architects, California. It is intended to inform California residential property owners about the opportunity to create Accessory Dwellings throughout California, as well as the challenges involved in their planning and construction. It is our goal to inspire property owners to create beautiful, useful, efficient, and thoughtful ADU projects that are successful in all the dimensions of sustainability: social, environmental, and economic.designed by architects other knowledgeable building professionals.