Add a room — tap a wall, size it, done
From the Build panel choose Add Room, tap the wall to build against, size it with snapping, and tap Done — the shared wall becomes interior automatically.
Most plans grow sideways: a bedroom off the hall, a mudroom on the back, an office beyond the garage. Drawing each of those wall by wall is slow and error-prone at the corners. Add Room builds the whole room against a wall you already have, and merges it in cleanly.
The tool lives in two places — the main editor's Build panel, and the Edit Floor Plan Shape editor — and both produce the same result: a new enclosed space whose shared wall becomes an interior wall running its full length, with corners that meet exactly.
Step by step
- 1
Choose Add Room
In the Build panel (Structural & Interior on a phone) tap Add Room. The banner reads Tap an outside wall to place an adjacent room — you can resize it right after by dragging its corners.
Add Room sits with the structural tools. - 2
Tap the outside wall it sits against
Tap the exterior wall you want the new room next to. A small room appears already attached to that wall, with a handle on each corner and the instruction Drag the corners to size the room, then tap Done.
The room appears attached, with corner handles. - 3
Size it by dragging the corners
Drag the outward corners to set width and depth; the two corners on the wall slide along it. Measurements update live as you drag, and the edges soft-snap when they line up with an existing wall, so a 12 × 10 bedroom is exactly 12 × 10. If the room overlaps the plan, the overlay tells you to shrink it before you can continue.
Live dimensions and snapping while you drag. - 4
Tap Done
The room merges into the plan. The shared wall becomes an interior wall that runs the full length between the two rooms and meets the surrounding walls exactly at the corners — no small gap. The new space is enclosed, so it gets its own name, area, and flooring immediately; add a door between the rooms from the Build panel.
Merged: shared wall interior, both rooms named. - 5
The overlap guard
Add Room won't drop a room on top of the plan. Tap a wall with no open space beyond it and you'll see A room here would overlap the existing plan. Try tapping an outer wall with open space beyond it. Pick another wall.
No overlaps — it asks for an outer wall with space beyond. - 6
Or type the depth in the shape editor
Open Edit Floor Plan Shape, choose Add Room, tap an outside wall, set Room depth, and tap Add room. Then use Split Walls to divide the new space, or drag its corners freely. Tap Update Floor Plan to save.
Tips
Build from the room you have
Add the hall first, then rooms off it; each new room snaps to the walls that already exist.
Split instead of adding when the space is inside
If the new room is inside the existing footprint (dividing a big space), use an interior wall or Split Walls, not Add Room.
Common mistakes
Tapping an interior wall
Add Room attaches to outside walls only. Tap the exterior wall on the far side of the space you want.
Forgetting the door
Two enclosed rooms need an opening between them. Add a door on the shared wall from the Build panel.
Frequently asked questions
Does the new room share a wall with the old one?
Yes. After Done, the wall between them becomes a single interior wall that runs the full length and meets the surrounding walls exactly at the corners.
Can I set the room's exact size?
Drag the corner handles with live measurements and snapping; in the shape editor you can also type the room depth before adding it.
Can the room overlap the existing plan?
No. The tool refuses placements that would overlap and asks for an outer wall with open space beyond it.
Start designing your room
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