The short answer: a site plan shows the whole parcel and locates buildings, property lines, setbacks, access, site features, utilities, and the public right-of-way. A floor plan enlarges one building level and shows rooms, walls, doors, windows, stairs, fixtures, and interior dimensions. When a decision affects both land and interior space—an addition is the clearest example—show it on both drawings and make the footprint, orientation, and dimensions agree.
This guide is a U.S. residential drafting and permit-handoff reference, not a universal submittal standard. Local requirements vary by project and jurisdiction. The examples below synthesize current public guidance from Portland, Seattle, and Austin, last checked August 26, 2026. Confirm the actual checklist, survey basis, code edition, and professional-seal rules with the authority reviewing your project.
The boundary: land relationships versus interior relationships
Use one question before placing a fact: what relationship is this drawing asking a reviewer to verify?
- Put a fact on the site plan when the answer depends on the parcel, a property boundary, another structure, grade, access, a utility route, vegetation, drainage, or the public right-of-way.
- Put a fact on the floor plan when the answer depends on spaces and construction within one building level: room use, wall layout, openings, fixtures, circulation, stairs, or interior dimensions.
- Put it on both when the decision crosses the building envelope. The site plan locates an addition against the lot and setbacks; the floor plan explains the new room and its connection to the existing house.
- Put it on another drawing when neither plan can answer the question. Exterior height belongs on elevations; vertical construction and grade relationships belong in sections; foundations, framing, grading, drainage, and utilities may require dedicated structural or civil sheets.
That boundary prevents two common errors: using a floor plan as though it proves where the house sits on the lot, and stuffing interior details into a site plan until the parcel relationships are unreadable.
What belongs on the site plan
A site plan normally shows the entire lot, not only the corner where work occurs. Portland's residential permit-plan guidance requires its site plan to show the entire lot and distinguishes its usual scale from the larger scale used for floor plans. Seattle's Tip 103 likewise treats the site plan as a required permit document and provides separate basic and enhanced examples.
Start with reliable source geometry, then show the information the reviewer needs:
- property lines, lot dimensions, street names, alleys, easements, and a north arrow;
- footprints and labels for existing, proposed, and removed structures;
- dimensioned distances between structures and property lines;
- setbacks, yards, and other zoning control lines relevant to the scope;
- driveways, parking, walks, patios, retaining walls, and other hardscape;
- trees, grade information, drainage features, and environmental constraints when required;
- visible or documented utility and service locations relevant to the work; and
- curbs, sidewalks, planting strips, and other public right-of-way information.
Portland's detailed site-plan guide specifically separates existing and proposed site development and calls for public right-of-way information regardless of project scope. It also warns that its flat-lot sample is not sufficient for floodplains, environmental overlays, or river-related overlays. That is a useful limitation for any template: a clean generic diagram is not evidence that a complex site has been documented.
Do not invent parcel geometry from an aerial image. Aerials can help orient a draft, but tree canopy, roof overhangs, camera angle, and image rectification make them an unsafe substitute for a boundary survey or official record. Label unverified information FIELD VERIFY rather than giving it false precision.
What belongs on the floor plan
A floor plan is a horizontal view through one building level. It should make the usable spaces and the construction around them inspectable. Portland describes one plan for each affected level and asks for existing and proposed work to be clear. Its residential guidance includes full- and partial-height walls, room size and use, windows, structural members, stairs, fixtures, equipment, and smoke detectors. Austin's Residential Plan Review guidance adds scale, room labels, wall measurements, ceiling heights, opening sizes or schedules, life-safety devices, plumbing-fixture locations, guards and handrails, and room areas to its floor-plan list.
A useful floor-plan base therefore includes:
- the level name, scale, north arrow when required, and overall dimensions;
- exterior and interior walls with enough information to distinguish their construction;
- room names, uses, and controlling dimensions;
- doors with swings, windows, stairs, and changes in level;
- plumbing fixtures and fixed equipment relevant to the review;
- structural references, rated assemblies, accessibility clearances, or egress information when applicable; and
- a clear graphic distinction among existing, removed, and proposed work.
The floor plan does not replace a framing plan, reflected ceiling plan, electrical plan, or interior elevation. It may carry coordination symbols for those systems, but the sheet must remain readable at its issued scale.
Worked example: a rear study addition
Assume a 12-foot-by-16-foot study is added to the rear of a one-story house.
On the site plan, draw the existing and proposed building footprints. Dimension the new footprint to the relevant property lines and existing structures. Show the street, driveway, right-of-way, north, applicable setback lines, and any tree, utility, drainage, or grade condition affected by the addition. The site-plan question is: can this footprint occupy this location on this parcel?
On the floor plan, draw the study's walls, room label, dimensions, windows, and the opening that connects it to the existing house. Show what wall or opening changes, how occupants enter and leave the room, and any structural or trade references required by the project. The floor-plan question is: does this level work as a building layout?
Then coordinate the shared facts:
- The addition's outside dimensions match on both drawings.
- The side of the house receiving the addition matches the north arrows.
- Existing openings shown near the work do not move without a scope note.
- The proposed footprint area agrees with the zoning or coverage calculation.
- Revision clouds and dates identify the same change on both sheets.
If those checks fail, the problem is not cosmetic. The reviewer, estimator, layout crew, and inspector are being given different projects.
A sheet-selection matrix
| Project fact | Site plan | Floor plan | Often needs another sheet |
|---|---|---|---|
| Property line and lot dimension | Primary | No | Survey or plat establishes basis |
| Building footprint and addition location | Primary | Coordinate | Foundation plan |
| Setback and distance to another structure | Primary | No | Zoning calculation |
| Room use, walls, doors, and windows | Footprint only | Primary | Door/window schedules |
| Stairs and interior circulation | Access context only | Primary | Section and details |
| Grade, drainage, and retaining condition | Primary context | No | Grading/civil plan and sections |
| Utility route across the parcel | Primary | Connection point | Civil or trade plan |
| Exterior height and roof form | Footprint only | Limited | Elevations and sections |
The matrix is a routing tool, not a minimum permit checklist. A jurisdiction may require the same fact on several sheets so different review disciplines can find it without reconstructing the set.
Common failure modes
The site plan is only a bigger floor plan. Rooms are visible, but property lines, right-of-way, setbacks, access, and neighboring structures are missing. Reduce interior detail and restore the parcel relationships.
The floor plan is only a smaller site plan. The building footprint is present, but room uses, walls, openings, fixtures, dimensions, and circulation are absent. Enlarge the level and show the construction question.
A generic template is treated as measured truth. AI can organize a brief and create a legible first draft. It cannot measure a lot, locate a legal boundary, establish grade, choose a local setback, or certify code compliance. Keep source and verification status visible for every controlling dimension.
The two drawings disagree. A footprint rotates, an addition changes size, or north points differently. Overlay the building outlines or compare a shared coordinate and dimension schedule before issue.
Everything is forced onto these two sheets. If a reviewer needs a vertical or construction relationship, add the correct elevation, section, detail, structural, or civil drawing. More labels on the wrong view do not create evidence.
The concrete next step
Write a source brief before drafting: jurisdiction, parcel-record source, survey status, project scope, existing and proposed structures, access, site constraints, affected floor levels, known dimensions, unknowns, and required reviewers. Then use ChatDiagram's site plan creator to structure the parcel view and its coordinated building footprint.
Issue the result only after a qualified person checks it against field measurements, survey or recorded-property evidence, the current local submittal checklist, and every companion sheet. A useful generated drawing makes missing evidence visible; it never fills those gaps by guessing.