Add a slab (add_slab): a home3dplan MCP tool

What it does

A floor no walls enclose, drawn on a storey from its corners in plan millimetres: a balcony, a porch, a landing, a canopy, a terrace deck. Not a roof: every storey already has a floor and a ceiling slab over its building, and a flat-roofed house is covered by its ceiling slab. Base is mm above the storey’s floor (0 when absent), thickness in mm.

A write. It saves one revision of the project, which appears in the open editor at once and can be undone there. Scope: **projects:write**.

Inputs

**projectId** (string, required): See the tool’s description.

**storey** (integer): Default 0.

**outline** (({ x: number, y: number })[], required): corners, plan mm; closed for you

**base** (number): mm above the storey floor

**thickness** (number): mm

What comes back

What changed, in words and in a structured form, and the link that opens the project in the editor on the right storey and view.

Tip: if the project changed in the editor between two calls, the write is refused as a conflict and the assistant opens the project again. Nothing is overwritten.

Ask for it like this

"Use add_slab on my project."

The assistant chooses the tool and fills its inputs from what you said; you do not name the tool or type its inputs.

Read next

• Draw walls
• Change walls
• Place doors and windows