---
name: ifc-quantity-takeoff
description: Extract construction quantities (lengths, areas, volumes, counts) from an IFC file with IfcOpenShell and deliver a CSV plus a summary by storey, type and material. Use when the user asks for quantities, a takeoff, a bill of quantities, "cantidades de obra" or "metrados" from an IFC or BIM model.
---

# IFC quantity takeoff

## Inputs
- Path to one .ifc file (IFC2X3, IFC4 or IFC4X3).
- Optional: the element classes to measure. Default: every IfcElement subclass that has a body representation.

## Procedure
1. Make sure ifcopenshell is installed (pip install ifcopenshell). Print ifcopenshell.version and the schema. Use the API of the installed version; if a call fails, look it up in docs.ifcopenshell.org rather than guessing.
2. Get the length unit scale with ifcopenshell.util.unit.calculate_unit_scale(model) and convert everything to m, m2, m3.
3. For each element collect: GlobalId, class, Name, type (ifcopenshell.util.element.get_type), storey (get_container, walking up to the IfcBuildingStorey), material (get_material).
4. Quantities, in order of preference:
   - base quantities from Qto sets: ifcopenshell.util.element.get_psets(element, qtos_only=True) -> source = "qto";
   - geometry: ifcopenshell.geom.create_shape(settings, element) with world coordinates, then ifcopenshell.util.shape (get_volume, get_footprint_area, get_side_area...) -> source = "computed";
   - otherwise source = "none" and record the reason.
5. Write quantities.csv (one row per element) and summary.csv grouped by storey + class + type.
6. Build the check list: elements with source "none", zero or negative values, IfcBuildingElementProxy, and probable duplicates (same type and same placement).

## Output to the user
- A short summary table (top rows by quantity) in the chat.
- The two CSV files and the check list.
- One sentence saying what percentage of elements came from Qto sets and what percentage was computed.

## Never
- Never fill a missing quantity with an average or an estimate.
- Never mix units in one column.
- Never modify the IFC file.