The simple answer
For most detached residential structures, the plans need to explain the location, size, use, layout, exterior appearance, and construction approach. The more the structure includes plumbing, livable space, mechanical systems, or unusual site conditions, the more coordination is usually needed.
Common detached structure projects
Detached garages and RV garages
Workshops, storage buildings, and hobby shops
Casitas and guest houses
Pool houses, studios, and other accessory structures
What the plan set usually needs to communicate
Exact requirements vary by jurisdiction and project type, but the same basic categories come up often. The city or county needs enough information to review the location, scope, structure, and code-related items without guessing.
Site placement
The site plan usually needs to show property lines, setbacks, existing structures, driveway access, easements where known, and where the new structure sits on the lot.
Floor plan and use
The plans should clarify the intended use, room layout, garage bay sizes, doors, windows, plumbing fixtures, and any livable or conditioned spaces.
Exterior and roof information
Jurisdictions often want to understand wall heights, roof form, exterior materials, openings, and how the detached structure relates to the main home.
Code and construction notes
Depending on the project, notes may address structure, fire separation, electrical, mechanical, plumbing, insulation, ventilation, drainage, and other review items.
Common review questions
A detached RV garage is not reviewed the same way as a casita with plumbing and conditioned space. A shop, garage, guest house, or studio may each trigger different zoning, building, structural, or utility questions.
- Setbacks, lot coverage, zoning, and accessory-structure limitations
- Height, roof design, exterior materials, and neighborhood or HOA considerations
- Garage door sizes, vehicle access, driveway layout, and maneuvering space
- Utility service, electrical panels, plumbing fixtures, HVAC, or conditioned areas
- Fire separation from the main house or property lines where applicable
- Engineering, truss design, or structural calculations when required
Why site planning matters
Detached structures often raise site questions before design questions. Setbacks, easements, driveway access, drainage, utilities, and existing structures can all affect where the building can go and how the drawings should be prepared.
Casita or guest house?
If the detached structure includes livable space, sleeping areas, a bathroom, a kitchenette, or independent utilities, the project may need a more detailed review path than a simple storage building or garage.
What helps before starting plans?
Helpful starting information includes the property address, parcel or assessor information, rough building size, intended use, desired garage door sizes, whether plumbing or HVAC is planned, and any known city, HOA, or site restrictions.
If the property already has older drawings or an existing structure that will be modified, as-built drawings may also help establish a clearer starting point.
Planning a detached garage, RV garage, casita, or shop?
Residential Design can help prepare residential plan sets for detached structures in the Phoenix Metro area and surrounding Arizona communities. Send the property address, rough size, intended use, and any jurisdiction comments or requirements you already have.