Rooms & walls
Draw walls with the Line, Box and Box Set tools; reshape geometry with the full Wall Edit Mode toolset; and keep rooms valid.
Walls are the backbone of every drawing, and rooms are the closed loops they form. This page covers drawing walls, the complete Wall Edit Mode toolset, and how rooms stay valid.
Drawing walls
The Wall tool has three sub-tools:
| Sub-tool | What it does |
|---|---|
| Line | Draw one wall segment at a time — tap to place, or press-drag-release to rubber-band a segment. |
| Box | Drag out a rectangle of four walls in one gesture. |
| Box Set | Place repeated boxes (useful for laying out several rooms quickly). |
While you place a wall, a small crosshair appears just up-and-left of your fingertip so the contact point isn’t hidden under your finger — the wall commits exactly at the crosshair.
Walls snap to the grid and snap to nearby corners as you draw, so endpoints meet cleanly. Close a loop back to its start to form a room; its name and floor area then appear at the centroid.
Drawing a box into an existing closed room
If you draw a Box inside a room that’s already a closed loop, the app asks:
- Create New Room — adds a fresh room from the box and makes it active (you’ll be asked again next time).
- Add to Existing — appends the four walls to the current room without replacing its boundary. This intentionally produces a two-loop shape that validation flags, so you can reconcile it later. This choice is remembered until you restart the sub-tool.
Wall thickness comes from layers
A wall has no single “thickness” field — its thickness is the sum of its material layers. A wall with no layer data uses the default stack (plasterboard 12.5 mm · timber stud 75 mm · plasterboard 12.5 mm = 100 mm). Editing the stack changes the wall’s drawn thickness instantly. See Wall materials & layers for the full layer system.
Wall length is always measured across the whole wall, start to end — a 4 m wall with a 1 m door in it is still 4 m long.
Wall Edit Mode
Select the Wall tool, then toggle the Edit Mode pill (top-centre). A 4-point red border frames the canvas as an unmistakable cue, a blue handle appears at the midpoint of every wall in the active room, and the sub-tool palette swaps to the editing tools. (You can’t change the active room while editing.)
| Tool | What it does |
|---|---|
| Move-by | Enter a value in mm and Add/Subtract to shift the selected wall perpendicular to itself by an exact amount. |
| Perpendicular drag | Drag a mid-wall handle to slide the wall sideways. With the grid on, it snaps on whole 100 mm crossings for a “hold-then-click” feel. Connected corners follow automatically. |
| Knife | Tap to arm, then tap a wall to split it into two at that point. Each half keeps the original wall’s materials; doors, windows, lights and radiators re-anchor to whichever half they sit on. |
| Fuse | The inverse of Knife: tap a handle to merge the wall with a collinear same-room neighbour that shares an endpoint (within ~10°). Openings and devices on the removed wall re-parent automatically. |
| Square Corner | Tap a corner to make its angle exactly 90°. The shorter of the two walls rotates; the longer one is pinned so the rest of the room is undisturbed. (Handles convex two-wall corners.) |
| Delete | Tap a handle to remove a wall — but only if the room still forms a simple closed loop afterwards (or was already invalid). Attached doors/windows/openings are removed with it; lights detach; the boundary is regenerated. |
Moving a wall propagates correctly through corners, connected partner walls and neighbouring rooms — see Multi-room & floors for shared-wall connecting and snapping.
Keeping rooms valid
A room must be a single closed loop. The validation checker reports:
- Degenerate walls — zero-length walls.
- Floating walls — a wall with a free endpoint not shared by any other wall.
- Disconnected components — detached islands in the room.
- Not a simple closed loop — a corner with the wrong number of walls.
- Polygon mismatch — the stored boundary doesn’t match the walls.
Try to solve snaps near-coincident endpoints together, drops zero-length walls, and recovers the boundary where the geometry allows. Detached islands and self-crossing loops must be fixed by hand. Invalid rooms get a dashed amber outline and an orange pill you can tap to open the issues sheet.
Empty rooms
Adding a room creates it with no walls — that’s normal (you’re about to draw into it). It’s allowed in memory but flagged invalid, and won’t block saving. The validation sheet lists empty rooms with a one-tap Delete empty room if you change your mind.