A guest house is a secondary dwelling on a residential property, separate from the main home, used to accommodate visitors, family members, or in some cases, tenants. Guest houses fall under R (Residential) zoning and are regulated as accessory dwelling units (ADUs) or accessory structures depending on the jurisdiction. The key zoning question is not whether your property is residential, but whether your specific residential zone permits a second dwelling unit on the lot.
The distinction between a guest house and an accessory dwelling unit matters for zoning purposes. Traditionally, a guest house was an accessory structure with sleeping quarters but no kitchen, used only for temporary guests and not as an independent dwelling. An ADU is a fully self-contained dwelling with its own kitchen, bathroom, and living space that can be occupied independently.
Many zoning codes still distinguish between the two. A guest house without a kitchen may be permitted as an accessory structure in zones where a full ADU is not allowed. Adding a kitchen converts the guest house into an ADU, which may require different zoning approval, trigger additional parking requirements, or be prohibited entirely in some residential zones. If your plans include a kitchen, you are building an ADU regardless of what you call it.
Where guest houses are permitted, common zoning requirements include maximum size limits (often expressed as a percentage of the main dwelling's square footage or an absolute cap such as 800 or 1,200 square feet), setback requirements from property lines (guest houses are typically subject to accessory structure setbacks, which may be smaller than primary dwelling setbacks), height limits that are often lower than what is allowed for the main house, lot coverage limits that include the guest house in the total building footprint calculation, and design standards requiring the guest house to be architecturally compatible with the main dwelling.
Some jurisdictions also require the property owner to live on-site (either in the main house or the guest house) as a condition of permitting a second dwelling unit.
Several states, including California, Oregon, Washington, and others, have passed legislation requiring cities to allow ADUs in residential zones. These state laws override local zoning restrictions that previously prohibited second dwelling units. If your state has passed ADU legislation, you may have the right to build a guest house with a full kitchen even if your local zoning code appears to prohibit it. The state law typically sets maximum standards for lot size, setbacks, parking, and unit size that local governments cannot exceed.
State ADU laws have dramatically expanded where guest houses and secondary dwellings can be built. Check your state's current ADU legislation, as these laws are being updated frequently.
If you plan to rent your guest house, either long-term or as a short-term rental through platforms like Airbnb, additional regulations apply. Long-term rentals may require a rental property registration or inspection. Short-term rentals are subject to local STR ordinances that may require permits, impose occupancy taxes, limit the number of nights per year, or prohibit STRs in certain zones entirely. Some jurisdictions allow long-term rental of guest houses but prohibit short-term rental, or vice versa.
Start by confirming the zoning on your property. You can look up your property's zoning on ZoningPoint.com to identify the current classification. Contact your local planning department to determine whether a guest house or ADU is permitted on your lot, what size and setback restrictions apply, and whether a kitchen is allowed. If you plan to rent the guest house, research local rental and short-term rental regulations before construction. Also check whether your state has passed ADU legislation that may override local restrictions.
It is important that you look up the specific zoning type for your parcel of land, because every jurisdiction has their own unique zoning and this is just a generalization.
