Our house plans are designed to meet national building codes, but not necessarily state or county codes. Therefore, these construction drawings do not include extensive HVAC or plumbing details. Your HVAC system will be determined by the size of your home and the types of units you use. Ductwork will be defined by the type of heating and cooling systems you use and your local building codes. Although plumbing fixtures are included in your home plans, the flow of water lines and sewer systems are site-specific and must be determined locally. You can discuss these details with your local builder.