A floor appears under your walls by itself as soon as they close a room, and it follows them from then on. It is a real thing you can select: double-click the empty floor of a room and the panel gives you its level, thickness and finish. To draw one where the walls do not make one, press Z — the toolbar calls it Floor (a platform, a loft, a floor with no walls round it), in the Floors & levels group. Floors are free.
Where a floor’s outline comes from
It follows the walls. The edge stops where the construction says it should: the ground floor and anything below it run to the walls’ outer face, because the wall bears on that slab; upper floors stop at the inner face, because the wall runs continuously past them. A courtyard inside a ring of walls stays open — the floor is what the walls enclose, not what their bounding box covers.
Or you draw it. The Floor tool’s panel has a Create dropdown to set before you draw:
| Create | What you get |
|---|---|
| Floor region | A floor outline you draw yourself, at the storey’s level. |
| Platform / loft | A platform over the floor, at the Level above storey you set. The floor below stays intact. |
| Loft with stairs and guarding | Draw the room outline; a platform, a flight up to it and guarding on its edge are fitted inside in one undo step. Each one is editable afterwards. |
Click the corners, then Enter or click the first point to finish.
Selecting a floor
A floor is a background body, like a room’s area: a press falls through it, so clicking clear of the furniture deselects and a drag from empty floor is a marquee. Double-click to select the floor itself. A split level’s level tag still selects on a single click.
The panel
| Field | What it does |
|---|---|
| Area | The net area, with what openings and steps take off a gross. |
| Level | Relative to the storey. The note under it reads the finished level against project zero. Changing it never changes which part of the storey this floor owns. |
| Thickness | The construction under the finished level. The finished level stays put; the slab grows downward. |
| Finish | The build-up between the structural top and the finished floor. |
| Boundary | Whether this floor follows the walls, is held, or is fixed — an outline of its own. |
With nothing selected, the storey’s own Floor section carries the default Thickness for floors on that storey and the Build-up they take from build-ups and U-values.
When the walls stop closing
A floor that loses its enclosure — you open a wall to extend the house — does not vanish. It keeps the outline it had, the plan check reports A floor no longer follows the walls, and your wall edits stop changing it until you press Follow walls again. Detach from the walls does the same thing deliberately: it freezes the outline as it stands so you can edit it by hand.
Where one floor meets another
A floor split into parts gets a Where it meets its neighbours section, one row per edge, each Closed, Steps or Open. Split levels covers those rows and the step geometry under them.
An edge that stands over a drop with nothing on it is reported by the plan check as A floor edge stands over a fall — see guarding.
Floors stack
A storey’s floor sits on the walls of the storey below. So thickening a floor, or raising a storey’s Wall height, lifts that storey and everything above it by the same amount: the building gets taller and the walls below still meet the slab. The lowest floor is the exception — it grows down into the ground, because project zero is its finished level.
An older plan
A plan drawn before floors became parts keeps one floor per storey, and its storey panel has two things a new plan does not need:
- Outline, which picks whether the automatic floor follows the walls’ outer face, their centreline or their inner face, and Upgrade floors to construction defaults, which moves every floor still at the centreline to the outer face on the ground floor and the inner face above.
- Convert floors…, which rebuilds the storey’s floors as parts you can split. It reports what would change before anything is written, and it is one undo step.
A drawn floor on such a plan also has an Edges row — click an edge to cycle it between open, a generated upstand and a flight of steps.
What this doesn’t do
- No edge drag handles on a floor that follows the walls. Move the walls, or detach it first.
- A floor is flat. There are no ramps and no sloped slabs; a change of level is a split level or another storey.
- Floors are not snap geometry. Other tools do not snap to a floor’s edge.
- No thermal role per floor. A floor’s part in the heat-loss sheet follows from where it sits.
Next
Split levels to put part of a floor at another level, and stairs to connect two of them — a stair cuts its own opening through the floors it passes.