Existing, demolition, and proposed floor plans: what belongs on each

The short answer: an existing plan records verified conditions before work; a demolition plan identifies only what will be removed or altered; a proposed plan shows the coordinated end state. Keep the same crop, orientation, scale, room names, and reference points across all three so a reviewer can compare them without mentally redrawing the building.

That distinction is not merely drafting etiquette. The City of Portland's current residential-addition guidance, checked August 30, 2026, requires existing and proposed layouts to be labeled, the whole affected floor to be shown, and demolished, retained, and proposed walls to be distinguished with a legend. Local submittal rules vary, but the information problem is the same everywhere: what is true now, what changes, and what will be true after the work?

Decide whether the project needs two sheets or three

“Existing and proposed” is a comparison. “Existing, demolition, and proposed” is a sequence. Use a separate demolition plan when the removal scope is complex enough that combining it with either state would obscure what stays, what goes, or how the work is made safe.

A small non-structural cabinet replacement may be clear with existing and proposed plans plus keyed notes. Removing several walls, changing openings, disconnecting utilities, preserving structural elements, or coordinating phased occupancy usually deserves a demolition sheet. The authority having jurisdiction controls the actual submittal set; the decision rule here is about legibility, not a universal permit mandate.

Before drawing, make a scope ledger with four columns: element, verified existing condition, demolition action, and proposed result. One row might read: wall between kitchen and dining | full-height partition, field-verified | remove finishes and studs; header subject to structural review | open connection with new cased opening. If a row cannot be completed without guessing, stop and verify the condition or label the unresolved item.

What belongs on the existing floor plan

The existing plan is a measured record, not an early version of the design. It normally shows:

• the entire affected floor, even when work touches only one room;
• exterior and interior walls with wall thickness, not a single-line bubble diagram;
• current room names and uses;
• doors, door swings, windows, stairs, plumbing fixtures, and other fixed elements relevant to the scope;
• dimensions sufficient to locate walls, openings, and affected spaces;
• the drawing scale and north arrow when the authority requires one; and
• verified irregularities instead of idealized right angles.

Mark uncertainty honestly. FIELD VERIFY is more useful than a precise-looking dimension copied from a listing photo. The City of Portland notes that previous drawings may be available in its permit records, but a record drawing is evidence of what was approved, not proof of what remains in the building today. Verify it before calling the sheet “existing.”

What belongs on the demolition plan

The demolition plan is a scope map. It should let an estimator, contractor, and reviewer answer the same question: what is being removed, and what is protected to remain?

Show removed walls, doors, windows, fixtures, casework, and openings using a consistent line type or graphic convention. Identify partial removals precisely: “remove wall to underside of header” is different from removing the header. Note temporary shoring, utility disconnection, hazardous-material work, and structural references when they are within scope.

Do not depend on red alone. Portland explicitly requires black-and-white drawings with readable line quality and contrast. A red dashed line can be helpful on screen, but the dash pattern, note, and legend must survive monochrome printing and scanning.

The demolition plan should also say what it does not authorize. Removing a partition finish is different from removing studs; removing studs is different from removing a bearing wall; removing a wall is different from removing the beam or header above it. Cross-reference structural, hazardous-material, mechanical, electrical, and plumbing documents instead of implying that an architectural hatch resolves those disciplines.

What belongs on the proposed floor plan

The proposed plan should read as the building after construction, not as existing plus a cloud of instructions. Show:

• final walls and wall types;
• final room names, dimensions, and uses;
• doors and windows with sizes, swings, and schedule references;
• stairs, fixtures, appliances, accessibility clearances, and rated assemblies where applicable;
• structural, mechanical, electrical, and plumbing references that affect the architectural layout; and
• enough dimensions to build and inspect the work.

If the demolition layer has to be visible for the proposed plan to make sense, the proposed plan is incomplete. A builder should be able to locate new work from stable datums and dimensions without reverse-engineering the removed geometry.

Worked example: open the kitchen and add a pantry

Suppose the measured first floor is 28 by 34 feet. The owner wants to remove the partition between the kitchen and dining room and build a pantry in the southeast corner.

1. Existing plan: show the full floor, the current partition, both room names, nearby openings, wall thicknesses, and dimensions to stable exterior faces. Mark the partition's structural status FIELD VERIFY until framing is confirmed.
2. Demolition plan: show the partition with the removal convention, identify doors or finishes to be removed, mark adjacent construction to remain, and reference the structural detail if the opening affects a bearing element. Do not draw the future pantry as if it already exists.
3. Proposed plan: show one coordinated kitchen/dining space, the new pantry walls and door swing, final room labels, construction dimensions, and relevant wall types. Carry forward every retained window and exterior dimension unchanged.

The example is intentionally modest. It demonstrates the state change without pretending that a floor-plan article can determine bearing conditions, temporary support, energy compliance, egress, ventilation, electrical layout, or permit approval.

The coordination checklist

Before issue, flip rapidly between the sheets. Unexplained movement is a coordination error: a window changes width, a retained door shifts, a room name changes without a wall changing, or the exterior footprint drifts. That “flicker test” catches errors faster than reading each sheet in isolation.

Then run a state-transition check for every changed element:

• If an element appears on existing and disappears on proposed, is its removal shown on demolition?
• If an element appears on proposed but not existing, is it clearly identified as new construction?
• If an element remains, do its location, dimensions, tag, and graphic convention stay consistent?
• If a note changes between sheets, is the change caused by the project rather than drafting drift?
• If work affects another discipline, is the cross-reference present on both the scope and final-state drawings?

This procedure is more reliable than checking the proposed plan alone because it tests the complete claim: baseline, authorized change, and result.

Common failure modes

Using the proposed plan as the demolition plan. A contractor can see the final opening but cannot tell whether adjacent finishes, services, headers, or doors are removed or protected.

Tracing from different baselines. Existing comes from a scan, demolition from a field sketch, and proposed from a new model. Small shifts make retained work look new and can corrupt dimensions. Establish one verified base drawing first.

Encoding status only with color. The drawing fails in monochrome print, photocopy, or a low-quality permit scan. Use line type, hatch, label, and legend together.

Showing only the remodeled room. Reviewers lose the route to exits, adjacent uses, smoke alarms, structural load path, and the relationship to the rest of the affected level. Portland's addition checklist specifically calls for the whole affected floor even when the work area is small.

Treating an old plan as an as-built survey. Buildings change, permit work can differ from constructed work, and undocumented alterations exist. Record the source and verification date for critical dimensions.

Letting the three sheets disagree silently. A retained opening moves, a wall thickness changes, or a room label drifts with no revision note. Use overlays or the flicker test before issue.

Where AI helps—and where it does not

A text-to-plan system is useful for turning a room list and dimensions into a first structured draft. It is not a measuring instrument and it cannot determine local code compliance from a prompt. If the problem begins with a scan or rough drawing rather than a clean room list, ChatDiagram's blueprint maker supports a conversational import-and-correct workflow. For a zero-sign-up scratchpad, FloorPlanCreator.org can separate measured existing rooms from a proposed version before verified dimensions move into a permit set.

Treat either output as a draft. Field verification, structural design, life-safety review, accessibility, and the authority having jurisdiction remain outside what a generated floor plan can certify.